Sharpening Part 23 – Stance & Grip

When the show starts, I am in my SpongeBob stance, and I walk like SpongeBob, and the first step that I take, I am SpongeBob.

Ethan Slater
Ok boiz and gurlz, ready to sharpen?!

Stances

There are several practical stances for sharpening, including standing, sitting on a bench or in a chair, squatting, kneeling on the floor, or sitting on the floor. With practice, all these stances can be made to work well.

When starting out, however, I think most people benefit from using a standing position with the stones placed on a workbench or table, or on a board spanning a sink. 

Whichever stance you choose, locate and be conscious of your center of gravity, (usually just below your belly button), and try to keep it at the same elevation while moving the blade forward and back. 

Flex your knee joints, and loosen your elbow joints and wrists. Locking up your wrists and elbows will make it impossible to avoid rocking the blade. This is important. Actively concentrate on allowing the wrist to rotate in a manner to keep the blade’s bevel flat on the stone’s face.

In the case of a normal resharpening job, instead of a major repair, remember the goal: to abrade and polish the last few microns of steel at the extreme cutting edge, using the flat bevel as an alignment jig, exactly as craftsmen have been doing for thousands of years.

Don’t let yourself get lost in the forest of trees and focus just on abrading and polishing the entire bevel. Focus the majority of pressure on the extreme cutting edge, and less on the rear of the bevel, but without lifting the rear of the bevel off the stone. In the case of Japanese blades, the rear of the bevel is all soft jigane iron and will take care of itself. Yes, it is a balancing act. Yes, it takes focus. Yes, you will make mistakes, overbalance, gouge the stone and mess up the cutting edge a time or two. Everyone since the day the first caveman tried to grind his stone axe on another stone has made that mistake, so don’t worry about it. You fell off your bicycle the first few tries, scraped your knees and elbows, survived, and now ride like the wind! Yiiiiiihah!

Get a Grip

The way you hold your plane or chisel blade during sharpening will greatly influence the quality of the end product and the stress placed on your hands during the process, so it is worth paying attention to.

There are as many was to hold a plane or chisel blade when sharpening as Baskin Robbins has ice cream flavors. And like ice cream, none are right or wrong, except Burgundy Cherry, which of course is superior to all others (ツ)。 In the interest of brevity, we will only look at three grip methods. If you are not using them now, I suggest you give each a try over a couple of sharpening sessions to see if they are an improvement or not. Feel free to adapt these or develop your own from scratch once you understand the key points.

The Gorilla Grip

First, let’s examine what I call the “Gorilla Grip.” With the plane blade resting ura facing up, the blade’s long axis pointing at 11:00, and the cutting edge furthest away from you, grip the blade’s sides with your right-hand’s thumb on the left side, ring finger and pinkie on the right, the tip of the middle finger resting on the right corner directly behind the cutting edge, and index finger extended alongside the middle finger. Then lift the blade and roll your ring and pinkie under it.

Rest the tip of the ring finger of your left hand on the left corner directly behind the cutting edge, with your middle finger and index fingers extended and their tips resting adjacent.

Extend your left palm over your right thumb’s last joint, and wrap your left thumb under the blade. You are now ready to rock-n-roll, without the rocking and rolling motion

The advantage to this grip is that it is very strong, ergo “ gorilla.” The downside is the blade tends to end up skewed on the stone because the right wrist must be twisted to keep the blade straight. Also, because the wrist joints are at very different angles with respect to the blade, and it is easy to apply a lot of force, extra care is necessary to keep the wrists firm but loose and rotating in harmony.

Notice how thumbs are poised to fit under the blade’s head
Four fingers pressing down on the blade’s ura as close to the cutting edge as reasonably possible.
Finger position on a chisel. The left hand thumb passes under the blade’s neck supporting it vertically, while the pad presses against the neck’s right side. The right hand thumb passes over the top of the neck, restraining the tool vertically, and presses against the neck’s left side firmly securing the neck between both thumbs. More fingers can press down on the ura in the case of wider blades. Conversely, only one finger can press on narrow blades.

The Three-finger Grip

The other grip is one I call “three-finger,”(指三本) after the most proper way of bowing in Japan when seated directly on the floor (preferably tatami mat) in the “seiza” posture with legs folded underneath the body, both hands touching side by side with the pads of three fingers of each hand extended and touching the floor in front of the knees, and the thumbs and pinkies tucked out of sight. Very proper, and elegant especially for ladies.

In the case of the three-fingers grip, the blade is oriented directly in front of and on the body’s centerline with cutting edge furthest away. The hands hold the blade in a more symmetrical fashion than the gorilla grip, with the middle and index fingers pressing down on the blade’s corners closest the cutting edge (depending on the space available), with the thumbs curled under the blade’s head (end opposite the cutting edge), and either the ring fingers or pinkies touching the blade’s sides to assist in lifting it.

The advantages to this grip are less tendency to skew the blade, looser wrists, and better control of bevel angle. The disadvantage is slightly less power because it is harder to get the shoulders over the blade. This is the burgundy cherry version, in your humble servant’s opinion.

The Three-finger Monkey Grip

A hybrid of these two methods is one I call the “three-fingered monkey.” Place the right-hand thumb alongside the blade’s left side, instead of under the head forming a combination of the gorilla grip and three-finger grip. This method provides a little more power than the three-finger grip, and less skew than the gorilla grip.

Is one of these grips best? It’s like riding a bike: None are wrong, but some work better than others.

 In all three of these grips, most of the pressure will tend to focus at the blade’s corners which can create uneven wear on the ura. While this may be unavoidable, especially in the case of narrow blades, try to focus the majority of pressure on the centerline of the cutting edge. It seems insignificant, but if left uncorrected, the resulting unbalanced pressure will cause the blade to wear quicker at the corners and become curved. Yes the blade is iron and steel and does not flex much, but it is a verifiable fact that the points where your fingers apply pressure will be abraded quicker.

There is a saying in Japan which is quite appropriate when talking about sharpening that says “Dripping water wears away stone.” In this case, just a little differential pressure from your fingertips will shape the blade over many weeks and many passes over the stone, wearing away both stone and steel in useful ways or not. It is worth being aware of this potential and paying attention.

Chisel Grip

The grip I use on chisels is very similar to the grip for planes, and varies with width. 

The long handle makes chisels tail heavy and a bit more difficult to manage so it is often useful to select a grip style that is absolutely stable using just a single hand.

Most solutions involve holding the chisel in the palm secured by middle finger, ring finger, and pinkie, with the index finger extended and centered right behind the cutting edge.

The index and middle fingers of the other hand can also be pressed near the edge and the thumb wrapped underneath the handle.

Polishing the Ura

Polishing a 70mm plane blade’s ura.

When polishing the ura of a blade, be it plane or chisel, make sure the stone is flat. If it isn’t, you will regret it later without realizing why.

Let’s look at a plane blade first. Notice in the photo above how my right hand is curled under the blade’s head supporting it while my thumb presses down on the bevel close to the cutting edge, a grip that makes it easy to apply a lot of pressure precisely while maintaining control of the blade.

Two fingertips of my left hand are pressing down on the bevel for a total of three pressure points. The thumb can press down as light or hard as you feel is necessary, but it typically applies the highest amount of pressure. It’s important the left hand fingertips apply equal downward pressure to avoid creating uneven wear (unless one corner of the blade specifically needs more pressure applied).

Try to remove nearly all the weight of the blade’s head from the stone so that all but a tiny amount of applied pressure is focused on the “itoura” cutting land at the blade’s extreme cutting edge. No good can come of wearing a trench into the ura’s side lands.

Move the blade in two directions at the same time: Mostly to and fro in line with the cutting edge; but also on and off the stone’s edge perpendicular to the cutting edge. This will help avoid wearing a trench in the side lands and produce a stronger cutting edge (IMO).

Keep the stone flat and reverse it frequently to ensure even wear and less wasted stone.

Concentrate your senses and develop hand-soul coordination : You are a leaf on the wind; Watch how you soar (Hoban “Wash” Washburne in Serenity). I hope you have better luck than Wash did…

In the case of chisels, I hold the handle in the palm of my right hand and place thumb and forefinger on opposite sides of the neck/shoulders pinching it between them. I place the tips of the fingers of my left hand on the bevel, and move right and left hand together. And as in the case of plane blades, I move the blade both forward and backwards and left to right at the same time.

Give it a try. What do you have to loose?

In the next post in this series on sharpening, we will look at which direction to sharpen in. Few give this matter any thought, but most should.

YMHOS

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or conveniently and profitably “misplace” your information.

Previous Posts in the Sharpening Series

Sharpening Japanese Woodworking Tools Part 1

Sharpening Part 2 – The Journey

Sharpening Part 3 – Philosophy

Sharpening Part 4 – ‘Nando and the Sword Sharpener

Sharpening Part 5 – The Sharp Edge

Sharpening Part 6 – The Mystery of Steel

Sharpening Part 7 – The Alchemy of Hard Steel 鋼

Sharpening Part 8 – Soft Iron 地金

Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

Sharpening Part 10 – The Ura 浦

Sharpening Part 11 – Supernatural Bevel Angles

Sharpening Part 12 – Skewampus Blades, Curved Cutting Edges, and Monkeyshines

Sharpening Part 13 – Nitty Gritty

Sharpening Part 14 – Natural Sharpening Stones

Sharpening Part 15 – The Most Important Stone

Sharpening Part 16 – Pixie Dust

Sharpening Part 17 – Gear

Sharpening Part 18 – The Nagura Stone

Sharpening Part 19 – Maintaining Sharpening Stones

Sharpening Part 20 – Flattening and Polishing the Ura

Sharpening Part 21 – The Bulging Bevel

Sharpening Part 22 – The Double-bevel Blues

Sharpening Part 23 – Stance & Grip

Sharpening Part 24 – Sharpening Direction

Sharpening Part 25 – Short Strokes

Sharpening Part 26 – The Taming of the Skew

Sharpening Part 27 – The Entire Face

Timber Frame Water Mill Reconstruction Project, UK Part 1

Written by Guest Author, Gavin Sollars, Timber Frame Carpenter, UK

The village is the token and pride of England; there are usually found in it vestiges of earlier life – cottages, manor-houses, farm-houses, with buildings of more or less historic interest; and who should understand them, their origin, their peculiarity of structure, better than the local carpenter?

Walter Rose, The Village Carpenter 
The reconstruction job site as seen from across the River Test. Notice the green netting installed to prevent things from falling into the environmentally-sensitive river.

Introduction 

I became acquainted with Stan early in 2019 when I decided to look at buying an Ootsuki Nomi. During my search I became skeptical of many of the Japanese tools that are widely available to the European market and, after a lot of research, I came across Stan’s contact details and sent him an email. Stan took a great deal of time to discuss with me what really motivated my purchase, the kinds of things I should take into consideration when looking at Japanese tools and went into detail about the intricacies of Japanese craftsmanship. The information he freely provided was invaluable, and with his help I feel I made a very good choice, and now have a tool that will serve me for my entire career.

I recently updated Stan with some pictures of buildings I had worked on and he asked if I would be willing to share them with the readers of his blog. The overall aim of these ramblings is to describe to you (who Stan calls his “Gentle Readers”) the general outlines of the reconstruction of an 18th century traditionally-jointed timber frame structure in a beautiful area of the English countryside in the summer of 2019. I hope that this article will give you an understanding of the work that was undertaken and also the enthusiasm I have for this archaic variety of building craft and carpentry as a whole. 

Project Background

Timber framing in the UK has enjoyed a resurgence in popularity over the last 30 or so years, with quite a number of small to medium sized specialists in the craft building new ‘post and beam’ style buildings that emulate the traditional frames of the past. These companies are mixing time-honoured design details and timber framing techniques with more modern methods of production: chiefly circular saws and portable chain mortisers to rough out the work. This deep understanding and appreciation of historic building vernacular made my employer (The Green Oak Carpentry Co.) well placed to undertake the reconstruction of this Project.

The Mill prior to 2018 fire

The company was awarded the contract to reconstruct the building as close to the original as possible.

The Project is situated to the North of the Test Valley in Hampshire County in Southern England on the banks of the beautiful River Test, famous for trout fly fishing and “gin-clear waters.” The original waterwheel powered a grain mill. It was later converted to paper production, and even later housed a generator serving the nearby Manor House. Unfortunately, the original structure was completely destroyed by fire in early 2018.

At 21 metres (68.8’) long and 5.7 metres (18.7’) wide, the main structure is situated on a small island created by a man-made diversion in the River Test. The river flows from the north and is then diverted via a sluice gate to the right. The river then widens into a pool and bubbles quickly along the west side of the building. The diversion along the east flank drives the turbine, and passes underneath a wing that links the main structure back to the existing dwelling and also houses the turbine and mill workings. 

Historical & Structural Considerations

The original building was “listed” with the Historic Buildings and Monuments Commission for England confirming the historical importance of the building on the one hand while placing restrictions on how any work to the building can be performed on the other. What remained of the original building after the fire was still subject to the Commission’s rules and regulations, of course. It once featured shorter posts sitting on top of a brick wall from approximately first floor height. In the wake of the fire the surviving outer brick walls were deemed too structurally unsound to bear a load – however, due to the walls being “protected” under UK law, they had to be preserved. To get around this issue we installed two outer plates running around the perimeter of the building with the lower of the two (D – below drawing) supported on metal brackets (C) connected to the back of the timber Jowl posts (B) by lag bolts. The full weight of these two plates, as well as the softwood stud wall with conventional insulation and weatherboarding is carried by these brackets transferring the load to the jowl posts (B).

A detail drawing (drawn by myself) of the steel bracket, showing how load was removed from the fragile existing wall. The drawing also explains the interplay between our frame and the other elements in the building.

Design & Construction Details

Framing work started in July 2019 with a team of eight carpenters framing the bulk of the structure over a period of five weeks in workshops off-site. A team of four transported the fabricated components of the timber frame to the jobsite, assembled and raised the frame, framed the hips and valleys, then fitted the common rafters and cut and assembled the jack rafters.   

Constructed entirely from European green oak, the structural frame is very utilitarian by design and lacks the aesthetic details like the curved braces typical in many historic timber structures in the UK. Nonetheless, it has some nice detailing that might not be obvious at first glance. 

The main posts (wooden structural columns) are mostly jowl posts (aka “gunstock posts”) that flare at the top with tenons that fit into both the top plate (beam running along the top of and connecting the exterior posts) the column and tie beam. Historically, jowl posts were cut from the flaring grain of the base of a tree. These butts were often quartered and each post placed in the building adjacent to its sibling. I believe that this is a similarity historic English carpentry shares with its Japanese counterpart.

Here you can see the cross frame construction 

The dominant style of cross frame (or bent in North America) features a bridging beam (the large beam that spans the first floor and carries the common joists), a tie beam which spans the top plates. This beam stops the wall frames from spreading under the load from the roof. And then a simple truss design consisting of two vertical studs and an upper collar with short stub ties jointed horizontally between the principle rafters and studs. The purlins (the members that run the length of the roof) are ‘clasped’ between the stub tie and the principal rafter.  

The main roof frame is comprised of bridled common rafter pairs, a pre-Georgian (prior to 1714) hip gable at one end and a standard gable at the other. A pre-Georgian hip is the English name for a hip rafter that is usually square in section and canted so that one edge is in the plane of either the gable or the main roof. Hip roofs were historically framed in this way until carpentry methods changed and more of a ‘hip board’ set plumb with jacks pitched onto the sides became the preferred method of hip framing. 

The pre-Georgian hip gable. The effect of canting the hip rafter in this way means that the jack rafters pitched from the two walls have a side cut angle on top and a square cut on the edge, but the jack rafters on the gables have a more complex (and comically named!) ‘nuns crutch’ or ‘lip cut’.

The adjoining wing has a wider span and a higher apex to the main building, and the roof meets the main roof in a valley. These valleys are similarly canted into the plane of the roof like the hips. In the same way the hips produce two different jack rafter cuts so does the valley. You’ll notice that on the main building there is a square jack cut and on the linking building the jacks have a compound cut onto the valley rafter. After running into the valleys, two small hip rafters pick up the opposite slope of the main roof. All of these angles were found using the framing square. 

The junction between the wing and the main building looking back down the east wall.

The main building is split into two clear halves; one which is vaulted floor to ceiling, and the other which has two floors of joists.      

Green Oak Timbers

What sets this type of carpentry apart from other woodworking is its use of timbers that are rough-sawn and often of irregular dimensions, requiring an understanding of how to deal with imperfections. For example, timbers are often significantly out of square, and dimensions only approximate: according to the European standard allowable tolerances are +9mm ~ -3mm in section. 5mm of deflection per metre is also allowed. These significant irregularities complicate the carpenter’s job.

Moisture contents can be in excess of 60% in fresher felled stock and during the summer months the warmer weather can cause problems with drying and shrinkage – we often keep our stacks covered with hessian cloth in an effort to shade the timbers and reduce warpage and cracking. 

Timber framing using this challenging material teaches a carpenter much about the nature of wood as a living thing, the characteristics of the timbers, how they are likely to behave and what can be asked of them.  

The Layout Process

Carpenters have developed various layout systems over many centuries to overcome the difficulties of working with irregular timbers. In my company we use lofting, for example. According to this method, we draw out entire layups on the floor and align the outside edges of each member to these lines with any sectional irregularities placed on the inside of the building, whilst any crowning (deflection or bowing) is oriented upwards and outwards.

Once the layout is drawn full-scale on the lofting floor, the timbers are placed on blocks in alignment with their corresponding grid lines on the floor. The various members are then laid one over the other so carpenters can accurately mark out lengths and scribe the shoulders of the joints using levels and plumb bobs. 

The plumb bob is an ancient tool that you are doubtless familiar with – its importance in carpentry cannot be overstated. Plumb bob scribing, or ‘scribe rule’ layout, is a difficult thing to describe without actually seeing it done. What it boils down to is using a perfect reference in a less than perfect situation. By sighting down the plane of the timber by eye and comparing it at the same time with a plumb line a carpenter can gauge to what degree that face is out of plumb and then accurately replicate that plane on the shoulder of the intersecting timber. The shoulders of tenons and widths of mortices are carefully marked using this technique.

Once a frame is cut and fitted back together, a plumb bob can be used to accurately transfer and mark additional details up from the floor. In the case of this watermill I used a plumb bob to mark the theoretical positions of the purlin housings on each truss. The result was that, regardless of the amount of deflection or variation in thickness of each principal rafter, the purlin housing was maintained in a consistent level position down the entire length of the building.

A plumb bob being used to mark the principal rafter to tie beam joint. On the floor you can see the layout lines. We mark out each individual frame in a building full size on the floor with chalk lines, and then set up the timbers to those lines. This plumb bob belonged to my great grandfather who was also a carpenter. 

Frames are generally made up of wall frames (running the length of a building) and cross frames (spanning a building). Many of the timbers are therefore used repeatedly in multiple layups. In the case of main posts they are first framed into the exterior walls of a building. Once the walls are completed they are framed in the ‘cross frame layups’. To ensure that the posts return to the right height and rotation that they were in during their previous layups, we use scratched datums (often a set distance from the top of top plate) and rotation marks that allow us to wedge the timber to return it to plumb or level. 

Ensuring that a designated point on each timber is plumb and level is essential, particularly for those in multiple layups. It guarantees that a timber has been returned to the correct plane each time it is fitted up so that when it is stood up and connected to multiple beams, the rotation of each individual shoulder scribe is correct.   

Once the bulk of the main structure is framed we laid-up floor joist and ‘cogged’ the tie beams into the top plates. Traditionally tie beams were dovetailed into the plates but because the shrinkage of dovetails (green oak, remember) tends to cause the building to spread, it is now more common to see a simple cog used. A cog also slightly outperforms a dovetail in green timber when under tension.

Assembly and Erection at the Job Site

The building enclosed two concrete pads differing in elevation by about 200mm (8”). The base of each post therefore was designed to accommodate this change maintaining the design elevation of the building. This and other variables made laying-out of the building one of the most challenging I have ever been involved in.


This photo shows the “jowl posts” and the boom of the spider crane as assembly work is underway.

The only access to the site was a track through a field at the rear of the building and a small trackway and bridge over the river too narrow for a mobile crane to cross. The solution we employed was to bring in and set up a small spider crane in various places inside the building. The limitations of this machine required us to be very methodical about the assembly sequencing to ensure we didn’t obstruct subsequent lifts. 

Space was at a premium. Without a large area to unload the piles of timber, we had to unload the timbers and other materials in the field behind the property and then use a remote-controlled tracked carrier to ferry timber across the narrow access bridge.  

And, to throw one more element into the mix, the river is an extremely well-protected ‘Site of Specific Scientific Interest’, meaning we had to be very careful when cutting roof members to prevent sawdust from drifting into the water course. The scaffolders installed netting around the entire perimeter to prevent anything from falling from the scaffold. We also did the majority of our cutting away from the edge of the scaffold on a plywood deck we laid on the joists.

As the building began to take shape its scale became more apparent. At nearly nine meters high, it’s an impressive structure. 

Lessons Learned

I took away a lot of lessons from this building project such as managing levels on-site, and the importance of every trade singing off the same song sheet, as it were.

We had issues with the initial layout of the structure as it became clear that the structural steel that effectively served as the starting point for everything above it had not been installed at the correct elevation. The work was delayed while we sorted out this problem.

I also learned valuable lessons about effective joint placement. Because of the space constraints mentioned above, we were forced to erect the structure by lifting and placing each cross frame and then linking it back with its purlins. However, because the scarf joint landed on the wrong side of each truss, every time we craned a purlin into position, it was left temporarily unsupported at one end. These decisions were admittedly made early on before any proper site visits were made. A proper method statement was in place, of course, but the experience taught me that starting with the end in mind is important when planning.

I hope that you, Gentle Reader, gained some insight into the work that I am involved with and found it an interesting read. If you would like further information about historic timber framing in the UK, I recommend a small book titled Discovering Timber Framed Buildings by Richard Harris. 

– Gavin Sollars

Gavin Sollars hard at work

Thank you for your reading this article. It is rare to find a craftsman like Gavin with the skills and inclination to write about his work and a willingness to share it freely with others. Gavin did not write this to promote his company, but if you like this sort of thing as much as we do, please visit his company’s website and sign up for their newsletter.

In the next post in this series Gavin will outline the construction of the roof frame. Please stay tuned.

YMHOS

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.”

Hammers to Use With Chisels Part 1 – Hammer Varieties

Yet such is oft the course of deeds that move the wheels of the world: small hands do them because they must, while the eyes of the great are elsewhere.

Elrond
A modern-style 750gm gennou head hand-forged by Kosaburo, hung with a black persimmon handle. I purchased this high-quality head over 33 years ago. An heirloom tool and a good buddy.

This is the first article in a six-part series that condenses the advice we have given to our Beloved Customers over the years regarding the hammers they should use with our chisels. While some of this information is relevant to our warranty, all of it is relevant to how well our chisels will perform and the pleasure our Beloved Customers will enjoy using them.

In this first part we will focus on the varieties of hammers we recommend. Subsequent articles in this series will focus on appropriate hammer weights and faces, how to use a chisel efficiently, the “chisel cha-cha,” the importance of rhythm, as well as a discussion about health and hammers. There may even be a song or two to hum along with. Helluvalot better than a performance of Cats, and cheaper too.

In the future we will present several different series, one with more details about hammer heads, and another explaining why and describing how to make a handle for a Japanese gennou hammer (or any hammer for that matter), with scaled reference drawings. We will of course provide the entire contents of these articles in a single wiggling bundle to our Beloved Customers that purchase one of our gennou heads. Yes, there are more perks to being a Beloved Customer than simple toe-curling joy (ツ)。It’s a cunning plan, you see.

Hammer Materials

30mm Atsunomi by Kiyotada

We sell tatakinomi chisels such as oiirenomi, mukomachinomi (mortise chisels), or atsunomi all designed to be motivated by the most efficient method available, namely a steel hammer swung by human hand and arm. I won’t debate the pros/cons of steel hammers versus wooden mallets versus plastic mallets versus brass hammers versus unobtanium-platinum alloy hammers in this post because the physics are as obvious as a lemur in a lingerie shop (they’re a bit hairy, they jump and climb all over the displays and bras don’t quite fit them right) beyond noting that a hardened steel hammer imparts more energy to a chisel in a more easily focused and controllable manner than any other type of beater considering the economics of both initial cost and repair/replacement cost. Some may disagree; A mind is a terrible thing to taste.

The advantages of the steel hammer are quite obvious, even without doing energy calculations, but are there any disadvantages? Mochiron (Japanese for “of course”).

Steel hammers can concentrate so much energy on a tool handle so efficiently and so quickly that they may eventually destroy the handles of the sharpened screwdrivers sold as chisels nowadays in Western countries due to a faulty design detail. It’s this silly design flaw most modern Western chisels share that motivates people to use softer, fatter, energy wasting mallets made of wood, plastic or rawhide. So sad. 

An obvious solution is to use a steel hammer of a reasonable weight along with intelligent technique to effectively keep the energy imparted to the chisel within acceptable limits. But this may not be enough if the chisel design is weak.

Ooh ooh! I got’n idea. Why not design and manufacture a chisel that a steel hammer won’t destroy as a matter of course? Wow! Such an innovation would be right up there with the rumors I’ve heard of buggies that move without horses. Imagine that…

Fortunately, the tataki nomi chisels we sell are professional tools designed to be struck by steel hammers so they need not be coddled. They have a mild steel kuchigane (coned ferrule) fitted where the handle meets the blade, and a mild-steel hoop, or crown seated at the butt end of the handle. When properly fitted to a dense, straight-grained Japanese oak handle, this steel furniture does a great job of protecting the handle from splitting or breaking.

However, along with the handle, these parts do need to be setup properly to ensure they continue to protect the handle for a long time. We have provided clear instructions for how to perform this setup job here.

So, please use a hardened steel hammer with our chisels.

But there is more to hammers than just materials, so let’s continue onto the next subject.

Japanese Hammer Types

A Kosaburo head with a brand-new nuclear-flash colored Osage Orange handle

The traditional hammer used in Eastern Japan for striking chisels and general carpentry work is called a “gennou” pronounced “ghen-noh.”

Janus Coin

The gennou common to Eastern Japan is a simple symmetrical cylinder of one sort or another with a flat face on one end and a domed face on the other, often called the “ryoguchi gennou,” or the “Janus Hammer” by those with a classical education. No claws, no pointy tail. The flat face is used for striking chisels and pounding nails. The domed face is used for something called “kigoroshi” and for the last stroke when setting nails. It’s a handy tool and more stable in the swing than a claw hammer. It’s a matter of physics.

Japanese carpenters use a specialized nail bar for pulling nails effectively increasing the lifespan of their hammer handles, so claws are not necessary.

3 gennou heads. The far left head is a simple economy head. The center head is a higher-grade head slightly flared towards the ends. The far right head is an entirely hand-forged classical “swollen eye” tool by Kosaburo.

The Yamakichi style gennou head (see photo below) is another variety popular primarily in Western Japan. The tail is not pointy but rather a small square face that is useful for starting small nails and for “ tapping out” plane blades. The face typically has a slight curvature which is helpful for setting nails, but not enough to damage a chisel. The moment of inertia is less than the symmetrical gennou head so it is not as stable in the swing, but it is still a fine head.

A “Yamakichi” style head by Hiroki with a mellowed Osage Orange handle

The pictures below are of a gennou head called “Funate,” which translates to “boat hand.” I have heard it originated with ship carpenters, but am uncertain. The tail end is a small square as you can see from the photo, and is handy for setting nails. It makes a great finish hammer, but as a hammer for striking gennou it never appealed to me. But there are plenty of craftsmen that love this hammer.

a Funate gennou with a bubinga handle

Any of these hammers will do the job: it’s all personal preference.

Western Hammer Types

The purpose of this article is is not to suggest that our Beloved Customers must use a Japanese hammer when beating on our chisels. In fact, nearly any variety of quality steel hammer can be easily modified to do the job satisfactorily, including claw hammers, engineer’s hammers, or even ball peen hammers, so it isn’t necessary to buy a special hammer.

Please note that the closer the hammer’s center of mass is aligned with the center of the striking face, and the higher the hammer’s moment of inertia, the better. A cylindrical head is the closest to ideal from a physics viewpoint.

We’ll talk about the governing physics of hammers in future posts for those Gentle Readers that enjoy math.

In the next post in this series we will examine the type of face a hammer used to strike our chisels should have. Please come back and bring your lingerie-loving lemur friends. A Brazilian body wax is not required.

YMHOS

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or profitably “misplace” your information.

Other Posts in this Series “Hammers to Use With Our Chisels”

Part 1 – Hammer Varieties

Part 2 – Hammer Faces

Part 3 – Hammer Weight

Part 4 – The Chisel Cha-Cha

Sharpening Part 22 – The Double-Bevel Blues

The fool doth think he is wise, but the wise man knows himself to be a fool.

William Shakespeare, As You Like It
It is well with me only when I have a chisel in my hand – Michelangelo Buonarroti 1475-1564

In the previous post in this series on sharpening Japanese tools, we looked at philosophical points such as making tools a long-term investment, as well as the upsides, downsides and causes of the bulging bevel. In this post, I would like to touch on a subject that will make thoughtful people think and befuddled folks lucid: The Double Bevel.

The Double-Bevel

Some people advocate creating double-bevels (primary and secondary) bevels, or what is sometimes called “micro-bevels” on plane and chisel blades. Multiple bevels have three useful applications in my opinion:

  1. The first useful application is to repair a tool’s blade in the field when there is not enough time to do a proper sharpening job. If a blade dulls or chips in the course of a job, we can quickly add a secondary bevel at a steeper angle to the blade’s primary bevel in a few seconds and get right back to work, but there will be a price to pay later over many sharpening sessions to restore the proper bevel, so it is only a temporary, not a long-term solution;
  2. The second application is to quickly adjust a plane blade’s angle to reduce tearout immediately when proper sharpening is not possible. Once again, a lot of remedial sharpening becomes necessary afterwards. This application is usually restricted to the primary bevel, but we will look at a more esoteric and risky application below.
  3. The third application is to efficiently restore a blade’s bevel to the correct angle in the case where pixies or our inattention has made the blade angle too shallow.

Case 3 above often goes like this: A blade that cuts well suddenly starts dulling quickly, maybe even chipping. Whiskey tango foxtrot!?! When this happens, our Beloved Customers, being of exceptionally high intelligence, use the bevel angle gauge described in Part 11 of this series to check the bevel angle. They may discover the bevel angle has become too shallow for the wood it is being asked to cut.

Image result for lie-nielsen honing jig photo

We could increase the bevel angle by welding metal to the bevel and regrinding it, but such barbaric behavior would ruin the blade, so the most expedient way to correct the bevel is to add a steeper secondary bevel at the desired angle. We can grind this new bevel by hand, or use a honing jig like the Lie-Nielson widget. I find I can apply more downward pressure using this jig to get the job done sooner and more precisely.

Honing jigs are undeniably useful, but they often become an impediment to learning professional sharpening skills, and they are more time-consuming to use than freehand sharpening. Jigs can certainly make the sneaky snake of multiple bevels workable, but please don’t ignore the inescapable fact that if one uses a jig properly, over multiple sharpening sessions the result will be… let me think about it…. wait a second while I make a little sketch here…. oh yea, a flat bevel. Hmmm….

Hey, I’ve got an idea. When performing routine sharpening (not the 3 cases listed above), instead of taking shortcuts and adding micro-bevels which turn into secondary bevels and maybe even bulging bevels, why not start with a flat bevel and keep it flat? And then just maybe we could take advantage of the natural indexing properties of that flat bevel to sharpen freehand and save a lot of time NOT polishing skinny secondary bevels or fat bulging bevels? You know what, it just might work!

A honing jig is very helpful for making big angle corrections. I own several, but the Lie-Nielson model is my favorite: I use it every third blue moon. If you decide to use one, however, reserve it for emergency or drastic measures. Don’t let it become training wheels, kiddies.

The Nano-bevel

In this and previous posts we discussed bulging bevels, which are convex bevels on plane or chisel blades; secondary bevels and double bevels, which are additional bevels; and micro-bevels, which are a tiny secondary bevel. But there is another type of secondary bevel a clever Beloved Customer called a “nano-bevel.” I like this term and so will use it, but I caution you that, like all secondary bevels, you should employ this bevel judiciously.

We will go into freehand sharpening techniques in greater detail in future posts, but to avoid confusion when discussing the nano-bevel, we need to touch on some of those techniques now.

You may have noticed that, when sharpening freehand on every stone but the finish stone, most, but not all people do a better job by applying downward pressure on the blade only on either the push stroke away from their body or the pull stroke back towards their body, but not in both directions. This is because placing downward pressure in both directions tends to make the blade rock resulting in a less-than-flat bevel, or Saints preserve us, the demonic bulging bevel. As you can imagine, if this rocking motion gets out of hand on the rougher stones the bevel angle can get out of control quickly.

However, on the finish stone, it is most efficient to apply light downward pressure in both directions. The advantage is that a teeny tiny bit of unintentional rocking helps to ensure the last few microns of the blade’s cutting edge are thoroughly polished. And because the abrasive power of a finish stone is so small, there is no danger the bevel will become rounded, at least if you don’t get carried away. From the wood-shaving’s eye view, this creates a tiny bevel at the last few microns of the cutting edge. This is one example of a “nano-bevel.” Stropping produces the same result on a larger scale. There is also another type of nano-bevel for emergency use.

When using a finish plane on wood with twisty grain you have no doubt experienced frustrating tearout. The usual litany of solutions is to reduce the blade’s projection for finer depth of cut, skew the plane, oil and adjust the chipbreaker, resharpen the blade, adjust the plane’s mouth, or even slightly dampen the wood with a planing fluid such as water, whiskey, or unicorn wee wee. All these methods can help.

On the subject of planing fluid, water works well but dries slowly and can have problematic secondary effects. And unicorn products are dreadfully expensive nowadays, even on Amazon, so I prefer a smooth, inexpensive, industrial-grade busthead. Please ask Ken Hatch for a demonstration and recommendations for a good planing fluid next time he invites you over to his house for his world-famous tacos.

Please note that I don’t drink any planing fluid other than water. Of course unicorn wee wee is more addictive than OxyContin and drives mortals quite mad. And alcohol is yeast pee pee and deadly, but I prefer whiskey for a number of reasons. First, whiskey has a good water/alcohol ratio that wets the wood about the right amount of time and then evaporates cleanly. Too wet and it penetrates too deeply. Too dry and it evaporates too quickly. Isopropyl alcohol works fine too but it is considered a pharmaceutical in Japan and so is very expensive. As with other alcohol products not intended for internal consumption, it contains poisons added at the demand of greedy governments for the sole purpose of maximizing tax revenues. I don’t need those poisons touching my tools or my skin. Whiskey doesn’t contain poisons (other than alcohol, of course), it’s cheaper and smells better.

Another classic solution to reduce tearout of course is to use a plane with a steeper blade bedding angle, but what to do if you don’t have a high-angle plane handy? A traditional, jobsite-expedient solution used by Japanese woodworkers is to create a nano-bevel on the ura side of the blade. This is accomplished during sharpening while polishing the ura on the finishing stone by lifting the head of the blade just a itsy bitsy teeny weeny nat’s nosehair thickness during the final stroke, pulling the blade towards you, of course, creating a “nano-bevel” on the last few microns of the cutting edge at the ura, effectively changing the approach angle of the blade.

Be forewarned that this is only for emergency use, and that if you are careless, or use it too often, the nano-bevel will become a microbevel, your blade will be damaged, efficient sharpening will become impossible, the chipbreaker will cease to function, and the gods of handsaws may curse you so all your hair will fall out and your dog will barf whenever it sees you! Or is it your dog’s hair will fall out and you will barf? I forget.

Now where did I set down that jar of planing fluid….?

Conclusion

A wise man will seek to avoid shortcuts that save a bit of time short-term only to waste more of his time and money long-term. If you simply make the effort to train yourself in basic sharpening skills, pay attention, and keep the bevel flat, time, steel, and stone-wasting monkeyshines such as double bevels will be unnecessary.

We have talked about the cutting edge’s proper shape. Beginning with the next post in this series, we will examine how to use sharpening stones to make it that way. 

YMHOS

Well Dude, I’m done sharpening using my most excellent honing jig for now and am off to the beach on my chick magnet! Don’t wait up, Mom.

Sharpening Japanese Woodworking Tools Part 1

Sharpening Part 2 – The Journey

Sharpening Part 3 – Philosophy

Sharpening Part 4 – ‘Nando and the Sword Sharpener

Sharpening Part 5 – The Sharp Edge

Sharpening Part 6 – The Mystery of Steel

Sharpening Part 7 – The Alchemy of Hard Steel 鋼

Sharpening Part 8 – Soft Iron 地金

Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

Sharpening Part 10 – The Ura 浦

Sharpening Part 11 – Supernatural Bevel Angles

Sharpening Part 12 – Skewampus Blades, Curved Cutting Edges, and Monkeyshines

Sharpening Part 13 – Nitty Gritty

Sharpening Part 14 – Natural Sharpening Stones

Sharpening Part 15 – The Most Important Stone

Sharpening Part 16 – Pixie Dust

Sharpening Part 17 – Gear

Sharpening Part 18 – The Nagura Stone

Sharpening Part 19 – Maintaining Sharpening Stones

Sharpening Part 20 – Flattening and Polishing the Ura

Sharpening Part 21 – The Bulging Bevel

Sharpening Part 22 – The Double-bevel Blues

Sharpening Part 23 – Stance & Grip

Sharpening Part 24 – Sharpening Direction

Sharpening Part 25 – Short Strokes

Sharpening Part 26 – The Taming of the Skew

Sharpening Part 27 – The Entire Face

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or profitably “misplace” your information.

Protecting Natural Sharpening Stones

Groucho Mark

Outside of a dog, a book is man’s best friend. Inside of a dog it’s too dark to read.

Groucho Marx

Natural sharpening stones are wonderful things. At least the good ones are. Finding one that works well with our blades and sharpening style is a thrilling experience and a source of long-term joy. Such an excellent stone can be hard to find and will often be expensive, but whether dirt cheap or worth rubies, it will be delicate and need protection.

In a previous article we looked at how to select a natural Japanese sharpening stone: Sharpening Part 14 – Natural Sharpening Stones

In this post we will examine some methods to ensure your natural sharpening stone provides you long reliable service. I suggest you read this article aloud to your favorite stone to gauge its reaction. If you pay close attention, you may even see it wiggle just a tiny bit with gleeful anticipation, especially when you get to the parts about calligraphy, color selection, and skirts. Stones can be very fashion conscious, you know.

The Weaknesses of Natural Stones

The first thing to keep in mind is that Japanese natural stones are pieces of sedimentary layers that formed on the bottom of the ocean, essentially red-hot dust violently spewed high into the atmosphere by volcanoes, sifted and sorted by wind and waves and distance, and laid down on the seabed like pages in a book. They have defects even if you can’t see them. They naturally have top and bottom surfaces as well as side/end surfaces where the layers are exposed. Water tends to soak in-between these layers exposed at side and end surfaces sometimes causing the layers to separate and even crack in heartbreaking fashion.

This structure combined with the relative softness of the material makes most Japanese natural sharpening stones fragile.

The Stone Base: Objectives and Materials

So what can we do to avoid and/or mitigate these risks to our precious stones to ensure they are happy and will last a long time?

My first Ipe stone base. You can see the grooves on the surface cut for decking purposes.

The most important thing you can do to protect your stone is to make a durable base, and to attach your stone firmly to it. The base provides several benefits:

  1. Seals the stone’s underside from water penetration, reducing the potential for separation and cracking;
  2. Provides structural support reducing the risk of cracking, especially as the stone becomes thinner;
  3. Makes the stone easier to handle, reducing the chances of dropping it, and protects it to some degree from bangs, dings and chipping;
  4. Makes the stone more stable in use.

There are several options for materials from which to make a base. Probably the best material on paper is high-chromium stainless steel. I have never made a metal base but some friends have.

Wood is the classic choice, but it has some downsides, for instance, it can warp, crack, rot and bugs might turn it into both home and dinner. So if you select wood be sure to choose a suitable species and develop a base design that sidesteps these shortcomings.

Most people, including me, choose to make their stone bases from wood. Most woods will work. I enjoy experimenting, so at various times I have made and used stone bases made from White Oak, Hinoki, Alaskan Cedar, Honduras Mahogany, Teak, and Ipe. Alaskan Cedar is an excellent wood for this purpose, but the best wood so far has been Ipe. It’s amazing: dense, but tough; It absorbs very little water and won’t crack or rot; Once stable, it doesn’t warp. At all. Bugs hate it. I love it.

File:Roppongi-Mori-Tower-01.jpg
Roppongi Hills Mori Tower Building, Tokyo

So how did I learn about Ipe? An architect specified Ipe to deck an exterior engawa at a balcony on a commercial project I managed some years back, so I decided I had better investigate this material on the Client’s behalf. What I found in various installations in Tokyo and Yokohama was eye opening. A good example is the Ipe decking installed at Roppongi Hills Mori Tower in Tokyo. This building was completed in 2003. I have worked in a Client’s offices in this building off and on for 5 years.

The exterior wooden deck at RH is exposed to more nasty weather conditions than a postman, not to mention heavy foot traffic, but although it has turned grey, it has not split, warped, or rotted. The screws are still tight, and the surface shows very little wear despite several thousand people walking across it each day. Tough stuff.

Related image
Exterior observation deck at Roppongi Hills Mori Tower

So around 2010 when I bought my last replacement stone, I bummed a couple of decking cutoffs a local lumberyard had been using as stickers directly on the ground for years. The wood was wet and muddy, but was in good shape. I laminated them together to make the base pictured above. It has been better than any I made before that time.

A few years ago, I did another building with an exterior Ipe deck. The decking subcontractor had mixed in two very dark, almost black pieces of Ipe. At first glance I thought they were ebony. I had the subcontractor replace them for aesthetic reasons. Instead of throwing the boards away (they were already cut to irregular lengths), I scrounged them and made a second base for my favorite natural stone. Once again, excellent performance. Testing is complete.

The Stone Base: Design and Fabrication

Before you start cutting wood for your base, first flatten the bottom of your stone. It doesn’t need to be perfect, but you want at least 75% contact. A carborundum stone or diamond plate will work fine, but a cheaper and easier option is to rub the underside of the stone on a section of concrete sidewalk wet with running water from a garden hose. Be careful to choose a place with low foot traffic because the concrete can become polished and quite slippery as a result.

Depending on the shape of the stone, you may want to grind off rough spots and projections on the sides and ends too. Be careful when you do this to prevent spalling and other damage.

If the stone has visible cracks, let the stone dry in a warm dry location for a few days, then apply masking tape to both sides of the crack, and carefully soak a few drops of super glue deep inside. Hopefully this will prevent the crack from promulgating further.

Now that you have the stone’s final dimensions, make the base. Whatever wood you choose, select quartersawn pieces if possible for maximum stability against warpage, or laminate the base if not. Regarding dimensions, it needs to be thick enough to resist flexing much when pressure is applied during sharpening, and long enough to remain stable when pushed back and forth. Shape the ends so water runs off.

You can make it as attractive or as utilitarian as you like, but avoid creating too many nooks and crannies for stone mud to collect in. The base pictured above retains the beaded profile cut into the wood’s upper surface to drain water from a deck, and it does drain water away from the stone effectively, but mud tends to collect in between the grooves. Not a fatal flaw, but it takes a few extra seconds with a brush to clean.

Be sure to chamfer or round-over all the edges and corners

Place the stone in the exact position on the base you want it to remain forever and mark the stone’s perimeter on the base.

Sand the wood directly underneath where the stone will rest. Don’t sand with the grain, but diagonally to create a cross-hatched rough surface. Completely remove any dust.

Apply masking tape to the wood base at the outside of the stone’s outline.

Place the stone right side up on a flat surface and wrap, bend and fold a single strip of thin cardboard or manila file folder paper tightly around the stone’s sides and ends and secure it in place with masking tape to form both a skirt that seals tightly against the surface, and a reservoir to contain the epoxy used to glue the stone to the base.

Mix up some 2-part epoxy, enough the fill the reservoir at the stone’s underside plus a little extra. You want the epoxy to be thick, not runny. Any epoxy that will allow plenty of working time will do.

Force a little epoxy deep into the wood grain and sandpaper scratches with a small spatula or wood stick. Next apply the same epoxy to the bottom of the stone with your little spatula, and forcefully drive it into the nooks and crannies.

Pour the remaining epoxy into the reservoir. It should fill the reservoir all the way to the brim

Without letting the epoxy harden or flow out, set the stone on the base, or the base on the stone, whichever works best for you, in precise alignment with the masking tape outline you created earlier. Wiggle the stone a little to work any air bubbles out, and push the stone down hard until you sense it is contacting the wood.

Once the epoxy starts to set and become rubbery, but before it hardens, run a razor knife carefully around the stone’s perimeter cutting just a tiny bit into the wooden base, and then peel up and remove the masking tape and any epoxy squeeze-out. Be warned: this will be an armor-plated, DMV-style nightmare to cleanup later if you wait until the epoxy sets hard.

After the epoxy sets, finish the base with whatever material appeals to you. I soak mine in polyurethane thinned 100% and wet sand several times. I then wipe off any PU that remains on the surface. I guarantee you that any finish material you apply that remains on the wood’s surface will fail and look nasty after a few years of use.

I also like to apply a thin coat of Titebond Type III glue to the underside of the feet and base just for good measure. Does it make a difference? I dunno, but I’m a belt, suspenders, and staplegun kinda guy.

My second Ipe stone base. Naturally black as ebony and almost as heavy. I wanted an unusual but subtle shape, one that could not be produced by power tools, so I made the far ends straight, transitioning into a radius at the base’s top surface. This stone is an irregular shape but it does wonderful things to steel. I’m sharpening a Keisaburo 70mm blade using all the stone’s surfaces.

The Stone: Protecting and Reinforcing the Sides

It’s important to limit water from soaking into the stone’s sides along the sedimentary layers to prevent separation. In Japan it’s SOP to paint the sides with natural urushi lacquer, a toxic tree-sap that loves water and doesn’t easily chip. This material may be difficult to obtain outside of Japan and China, I fear.

Another option is an extremely high-solids (aka “goopy”) natural urethane made from the sap of the cashew nut tree called “Cashew.” The material is made in Thailand and sold in Japan, but it may be difficult to obtain outside Japan. Or you can just use a commercial urethane.

Whatever finish you use, it is best to apply the manufacturer’s recommended primer, or at least a thinned initial coat of the same finish to the stone’s sides and ends so it will penetrate thoroughly into the cracks and crevices further reinforcing the stone. Subsequent coats should adhere well to this primer coat if applied before it cures entirely.

Any color will work. I have a habit of painting any tools I might take to a demonstration or jobsite orange. It seems to stunt darwinian leg growth. Besides, orange was the color of the first GC I worked for back in Las Vegas many moons ago and it brings back pleasant memories. They painted everything orange.

One other thing some people do to reinforce their stones is to apply a strip or two of washi paper (traditional Japanese paper made from mullberry tree fibers) to the sides and ends using urushi lacquer, or whatever material they used for the stone. Despite being paper, washi is made from continuous fibers and is surprisingly strong.

Some people go so far as to use washi with printed images or calligraphy on it, and apply a clear coat of polyurethane over the top so the printing is visible. I have never done this before, but it does look interesting.

A large natural sharpening stone called a Numata Tora with printed washi paper applied to sides to reinforce against water infiltration and cracking. To the right you can see one of the cracks this is intended to control.

Some people use cloth but this beyond my experience.

Here is a link to a blog by an artist named Mr. Kobayashi about his sharpening tools with some photos of pretty stone bases. It is written in Japanese, but the pictures are informative. Not sure how well Google Translate would work.

The Stone: Storing & Transporting

Finally, I recommend you wrap your natural stone and its base in clean cloth or newspaper immediately after each sharpening session, while it is still wet, to protect it from dust and dings. After it has dried, store it in a box with a lid. A wooden box is nice, but a plastic one is more practical.

Here’s a link to a video about making a simple traditional Japanese tool box from softwood. If you haven’t made one of these before, they can be fun and quite useful. They don’t see much use on jobsites nowadays because the plastic ones are more durable and much better suited to loading onto construction vehicles.

The high-impact plastic box pictured below is one I use for my sharpening stones. Manufactured by Reese in Japan, it has “Tool Box” heat stenciled into the side. Tougher than boiled owl and stackable, these containers will keep the contents dry no matter how hard it rains so long as the water level stays below the lower lip of the lid. Spring clips at each end do a great job of keeping the lid closed and attached even if the box tumbles off the back of a moving truck onto the road. The road rash will be bad, but the tools will stay inside. The problem is the truck following too closely behind…. Don’t ask me how I know. (ಥ_ಥ)

A Reese brand toolbox. Made of high-impact plastic, these boxes are tough as boiled owl. Rainwater can’t get in, but water vapor can get out. And because they have a standardized footprint, they are stackable so they ride well in the bed of construction vehicles. Just make sure they are strapped down (ツ). This type of portable toolbox has almost entirely replaced the traditional wooden carpenter’s box for practical reasons.

YMHOS

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or conveniently and profitably “misplace” your information.

Sharpening Part 21 – The Bulging Bevel

This is what a flat bevel looks like. So sweet.

For everybody in their busy lives, you need to invest in sharpening your tools, and you need to invest in longevity.

Ryan Holmes

In the previous post in this series about sharpening tools we looked at why and how to true the ura, the hollow-ground area on Japanese chisel and plane blades. This post will focus on the opposite side of the wedge that is a cutting edge: the bevel. This discussion is relevant to all plane and chisel blades, not just Japanese tools.

Preface

Before we dive in, I need to clarify something.

Some of our Gentle Readers have been blessed with the opportunity to learn about tools from accomplished Japanese craftsmen, as was I, or have figured them out on their own. If you find this or other posts boring, please remember this blog’s primary purpose is to provide instruction to our Beloved Customers who have not had similar opportunities.

These Beloved Customers are located in many countries and range in experience from newbies to professional woodworkers, so I try to include both advanced information for the professionals, and detailed explanations so newbies can keep up. Consequently, these articles are sometimes long and wordy. I humbly request your kind indulgence on behalf of those who may benefit.

Investing in Longevity

The quote above by Mr Holmes is applicable to the all the principles of sharpening I have described in this series of posts so far. He is a computer dude, not a contractor, joiner or furniture maker, but it is no coincidence he chose to use handtool terminology: it is encoded in human DNA.

His first point is a self-evident admonition, but what about this “investing in longevity” stuff? By definition, an investment is an expenditure of time, resources and/or effort intended to produce a return greater in value than the expenditure. Then how do we go about investing in the longevity of our chisels and planes, and what return should we expect?

While simply grinding sharp edges on our tools helps with making things from wood, I don’t see it as an investment in tools. Rather, if we train ourselves in professional sharpening techniques, and use those techniques to maintain our tools so they function more efficiently and last longer, we can hope to obtain a real-world return we can quantify financially. The investment I encourage you to make is not in things, therefore, but in your own skills.

The Pros and Cons of the Bulging Bevel

The “bulging bevel,” as I call it, is a deformation too frequently seen in plane, chisel and knife blades. It is simply a cutting edge bevel that is protruding and convex instead of flat. In most cases a bulging bevel can make it difficult to properly sharpen a blade adequately, so it deserves our attention. Most bulging bevels are born unintentionally and are harmful, but some are hatched with a purpose in mind. Let’s examine the pros and cons, and throw in some scientific results just for fun. 

The geometry of the bulging bevel is clearly superior in a few applications such as carving chisels and knives used in a gouging, scooping motion where a rounded bevel provides better control. Another is chisels used for cutting large and deep mortises where a rounded bevel helps pop out waste easier. Only timber framers cut these kind of mortises, however, and most of them use machines to at least rough out the mortises.

Hidari no Ichihiro 42mm Oiirenomi. Nothing obese about this sweetheart.

Our Beloved Customers are, without exception, extremely intelligent people, so right now some of you are no doubt saying to yourself: “Self,” (that’s what they call themselves when they silently cogitate profound matters) does a rotund bevel make my blades sharper or duller?” Let us consider some scientific results.

When I was a grad student in Japan, a fellow student wrote his thesis on the efficacy in plane blades of the bulging bevel versus the flat bevel. He developed experiments, fabricated testing apparatus, and used scientific methodology and microscopic photography yielding indisputable results. We repeated some of his experiments, discussed his research, and pored over photographs and fondled shavings late into the evenings at his lab in Building 11 at University of Tokyo Hongo campus as I drank coke and he drank sake. I’m not sure he made it home some evenings.

The conclusion he reached was that, from the viewpoint of the wood, and based on the classic sharpness test of cutting rag typing paper, there is no difference in the cutting performance between flat and bulging bevels, so long as two conditions are met: (1) Both types are sharpened to the same bevel angle and same degree of sharpness; and (2) The bulge is not so large as to interfere with the cut. The “same degree of sharpness” condition in proviso 1 is critical to this discussion.

Let’s examine the cutting edge closely. It’s effective scope is only the last few microns (μ) or so of the blade’s width at the extreme edge. 1μ=one millionth of a meter. A human hair is 90μ in diameter. We need to precisely repair and polish this narrow strip of steel using our sharpening stones, but remember that working anything beyond this strip contributes nothing to making the blade sharp.

Here’s an important point we can learn from a careful examination: Given the same number of strokes to the same blade on the same stones over the same amount of time, it is difficult to make a bulging bevel as sharp as a flat bevel, unless one spends the time to use a sharpening machine and jigs as my grad school friend did in his research room.

But the most important point, and one I want you to grasp with both hands and feet and all your teeth is that the time expended and amount of stone consumed when sharpening by hand to a set level of sharpness at the last critical microns of a bulging bevel’s cutting edge is huge compared to a flat bevel. Sharpening using machines and/or honing jigs takes even longer.

In addition to time and cost, another factor we need to consider is certainty, because if we are going to invest the time and stones to sharpen a tool, we need to be sure it will consistently achieve the same level of sharpness every time. Unfortunately, the sharpness of the bulging bevel is uncertain because, instead of guiding the blade to ensure consistent contact between steel and stone at the critical location on the cutting edge, the shape of the bulging bevel causes a significant number of strokes to be wasted on polishing a mound of metal that does nothing to make the blade sharper, but is simply in the way. Not convinced? 

Consider the undeniable fact that, despite your best efforts, this irrelevant lump causes the blade to rock around on the stone’s surface like a boat over ocean swells, with the result that, given a fixed number of strokes, a high percentage of those strokes end up polishing the bulge instead of the cutting edge. This is important because, once again, the last micron of the blade is the only part that actually does any cutting, not the bulge. 

Please don’t misunderstand. I’m not saying that you can’t create a fiendishly sharp edge on a blade with a bulging bevel. I’m also not saying that, within reasonable parameters, a convex bevel cuts less efficiently or dulls quicker than the same blade with a flat bevel. It absolutely doesn’t, as my colleague’s research showed. Allow me to restate and summarize the facts so there is no confusion.

  1. It takes longer to create a given level of sharpness at the extreme cutting edge of a bulging bevel than a flat bevel, all else equal;
  2. It consumes more sharpening stone to achieve a given level of sharpness at the extreme cutting edge of a bulging bevel compared to a flat bevel, all else equal; and  
  3. There is greater uncertainty about the actual degree of sharpness achieved at the blade’s extreme cutting edge when sharpening a bulging bevel by hand compared to a flat bevel, all else equal. 

If you doubt these statements, you must find the truth yourself. Buy or borrow a quality loupe or microscope with enough magnification to detect the scratches left by your usual finishing stone. Start with a dull blade with a truly flat bevel, sharpen it freehand using a set number of strokes, and observe the scratches at the last few microns of the cutting edge with your microscope. Then test the blade’s sharpness with your skin or fingernail. Next, repeat this test with a dull blade with a rounded bevel using the exact same sharpening tools and procedures and the same number of strokes. Once again, observe the scratches and test the sharpness. My grad school friend and I performed this side-by-side experiment at the University of Tokyo several times, with consistent results. Actually, it was a bet and I won. He had to buy the drinks and snacks for a month.

The Causes of Bevel Obesity

Besides pernicious pixies, the most common cause of bevel bulge is simple carelessness, which you can take steps to avoid once you realize the causes.

It is human tendency to try to stabilize the blade’s bevel on the stone while sharpening by applying more pressure on the rear half of the bevel, resulting in the rear half of the bevel (which is all soft jigane in the case of plane blades, and mostly soft jigane in the case of chisels) being abraded quicker than the front half (which contains the harder steel lamination), causing the bevel angle to gradually decrease or even become rounded. Even the best craftsmen make this mistake sometimes.

To avoid this tendency, train yourself to focus pressure on the front half of the bevel closest to the cutting edge. At first, you may overbalance and dig the cutting edge into the stone a few times, but with practice and attention, it will become second nature. It is almost a meditative process. Every professional woodworker worth his salt must learn this skill.

There is nothing wrong with making mistakes when learning a muscle memory skill like freehand sharpening, but too many people can’t be bothered to learn, and then become frustrated when their skills don’t improve immediately. In the end, they become defensive, and twist themselves into knots defending their inadequate techniques. Patience, grasshopper.

BTW, don’t forget to use your handy dandy brass bevel gauge to both check the bevel angle while sharpening and to keep those piratical pixies away.

Hidari no Ichihiro 30mm Atsunomi. What ignorant savage would grind multiple bevels on this?

Another cause of the tumescent bevel is the use of secondary bevels or micro-bevels. We’ll look at these aberrations in the next post in this series.

To make multiple bevels work one almost must use a sharpening or honing jig of some sort. Many allow sharpening jigs to become a substitute for real sharpening skills they didn’t bother to learn. Such jigs can become, in effect, training wheels those who rely on them never grow out of. So sad.

Conclusion

I encourage you to “invest in longevity” with regards to your tools in three ways:

  1. First setup your planes and chisels properly so they will provide you with long, reliable and efficient service. Setting up chisels improves not only their longevity but in many case their performance too, strange though it may seem. I will post articles about setting up and maintaining Japanese planes in the future.
  2. Second, true the ura of your plane and chisel blades efficiently without reducing their useful lifespan needlessly, as described in previous posts; and
  3. Third, invest in yourself by developing and honing the hand skills necessary to sharpen your blades quickly and efficiently while wasting only the absolute minimum of valuable time, steel and stone.
Image result for image of mandalorian helmet

Please master the ancient and bedrock-basic skill of freehand sharpening. All it takes is an understanding of correct principles, followed by concentration and practice; The rest will follow. I promise. “This is the way.”

We will look at other causes of bevel obesity in the next post in this series.

YMHOS

Links to Other Posts in the “Sharpening” Series

Sharpening Japanese Woodworking Tools Part 1

Sharpening Part 2 – The Journey

Sharpening Part 3 – Philosophy

Sharpening Part 4 – ‘Nando and the Sword Sharpener

Sharpening Part 5 – The Sharp Edge

Sharpening Part 6 – The Mystery of Steel

Sharpening Part 7 – The Alchemy of Hard Steel 鋼

Sharpening Part 8 – Soft Iron 地金

Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

Sharpening Part 10 – The Ura 浦

Sharpening Part 11 – Supernatural Bevel Angles

Sharpening Part 12 – Skewampus Blades, Curved Cutting Edges, and Monkeyshines

Sharpening Part 13 – Nitty Gritty

Sharpening Part 14 – Natural Sharpening Stones

Sharpening Part 15 – The Most Important Stone

Sharpening Part 16 – Pixie Dust

Sharpening Part 17 – Gear

Sharpening Part 18 – The Nagura Stone

Sharpening Part 19 – Maintaining Sharpening Stones

Sharpening Part 20 – Flattening and Polishing the Ura

Sharpening Part 21 – The Bulging Bevel

Sharpening Part 22 – The Double-bevel Blues

Sharpening Part 23 – Stance & Grip

Sharpening Part 24 – Sharpening Direction

Sharpening Part 25 – Short Strokes

Sharpening Part 26 – The Taming of the Skew

Sharpening Part 27 – The Entire Face

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or profitably “misplace” your information.

Sharpening Part 20 – Flattening and Polishing the Ura

A mind needs books as a sword needs a whetstone, if it is to keep its edge.

George R.R. Martin

Now that we are geared-up and our sharpening stones are flat, let’s make our blade sharp. The first step in sharpening a new blade is truing the ura. So let’s get to it.

General

All standard chisel blades and plane blades, whether Japanese or Western, need to have a planar flat or ura that it will be in contact with the sharpening stones its full width, and ideally, full length. Perfection is not necessary, however, so don’t let yourself get obsessive. If the ura is arched (concave), for instance, so it is in contact with a flat sharpening stone near the neck of a chisel, or head of a plane blade, and the cutting edge, that may be workable, but it must be in complete contact right behind the cutting edge. I cannot stress this importance of this point too strongly.

Once the ura of your chisel is flat and true, you should not need to true it again unless the blade needs major repairs. Japanese plane blades, on the other hand, are a little more complicated because repeated sharpenings tend to gradually wear out the land right in front of the cutting edge, called the “ito ura,” and the bevel must be tapped-out to compensate, and the ura re-flattened. I won’t delve into the subject of “tapping out” the ura of plane blades in this post but will save it for future discussions about Japanese planes.

Evaluate the Ura

The first step in flattening or truing an ura is to evaluate its condition. Don’t start grinding away willy nilly without first checking it and making a plan. If you find you cannot stop yourself, don’t walk but run to the nearest pharmacy and buy a bucket of the medicine discussed in part 19 in this series about maintaining sharpening stones.

There are several ways to check the ura’s condition. A narrow straightedge works well in most cases. Place the edge on top of the full length of the shiny land at one side of the ura all the way to the cutting edge. Keep the straightedge touching the land; Don’t let it span the hollow- ground urasuki. Hold the straightedge and blade up to a strong light source and look for light passing between them. This technique is quick and dirty and will suffice in most cases, but does not tell you a lot about twist.

Use a straightedge to check the right and left lands for flatness. It doesn’t do any good to span the hollow-ground urasuki, so don’t bother. These photos are taken from above for clarity, but you want to hold the blade and straightedge together up to a strong light to observe any light showing between them that will indicate a gap. I am using a small square, but a simple small straightedge is more convenient. This takes a bit of coordination so be careful not to drop a chisel on your toe. I’ve done this once or twice before. Monkey-football.
This is a 30mm Sukemaru atsunomi, a famous brand and an excellent and powerful chisel hand-forged by Mr. Usui from Shirogami No.1 Steel. It’s in pretty good shape, but can benefit from a little truing as can most new chisels and plane blades.

Another method to check the ura for planar is to paint the shiny lands with dark marking pen ink or Dykem liquid, apply a bit of fine sharpening stone mud to a piece of flat glass, like the piece mentioned in Part 17, and rub the blade’s flat or ura over the glass. The high spots will become obvious. If the ura is banana shaped (convex), mark the high spot with your marking pen. More often than not, the ura of chisels will be generally flat, but the last 6mm or so of the cutting edge will be curved upwards towards the chisel’s face.

I learned two things from my examination of this Sukemaru brand atsunomi. First, there is a high spot (convex) at the skinny land on one side located approximately 1/2 to 5/8 the blades’s distance from the cutting edge. The land on the other side seems a little low. Hmm, curious. This is a bit unusual, but it happens when a blade warps during heat treat, which Shirogami steels tends to do frequently.

The second problem I observed was that the last 3~4mm of the land right behind the cutting edge curves downward away from the ura just a tiny bit, enough to cause problems.

I next need a plan to resolve these problems with a minimum of time and effort and without making things worse.

Make a Plan

The temptation to start grinding away immediately will be powerful. If it becomes too much, take a coffee cup or three of the medicine mentioned above and slather it on your head forcefully. Don’t hold back, for Pete’s sake, rub it in really good now. Some say my excessive use of this medicine is why I am as bald as an egg, but I prefer to believe it is caused by the light radiating from my gigantic brain (ツ). Thank goodness for my aluminum foil skull cap with its protruding copper wires!

Any plan needs goals and objectives. In this case the goal is a perfectly planar ura, but if this goal is difficult to achieve quickly there is an objective you should plan to achieve immediately in any case, one that may make it possible to achieve the larger goal over multiple routine sharpening sessions without any special effort.

As I keep harping, to make a chisel or plane work well, you need a flat area right at the cutting edge. This is where the cutting occurs and the area I need to keep sharp, so I will make creating this flat area the first objective in my plan, and then determine the steps to achieve it. Make certain every step in your plan and every stroke on the stones gets you closer to this objective, not further away. This means working smart.

If the blade is arched (concave), touching at two points, one near the neck of the chisel blade, or head of the plane blade, and at the other at the cutting edge, and not in between, all is well. I recommend you leave a blade like this as-is because after a few sharpening sessions the ura will become flat and twist-free without any special effort, and the blade will become very sharp and be entirely functional.

If the blade is wavy (rare) or banana-shaped (convex), your plan needs to take those details into account.

I located the highest point of the bulging area at the ura and marked a line across it with my marking pen. I then measured halfway between this line and the cutting edge and made another line. This area we will call the “focus line.” It is here where I need to focus the most pressure when grinding down the ura, not the entire length of the blade.

The purpose of doing all this prissy planning and layout work is to protect the right and left side lands from being wasted unnecessarily. Newbies try to work the entire length of the blade, but this is illogical and ignores three points. The first point is that the majority of the metal I need to waste is usually located to the right and left of the land nearest the cutting edge, not the full length of the blade, so there is little benefit to grinding the entire ura. The second point is that the side lands are thin as a blade of grass and will abrade very quickly with almost no effort. Besides, without using large plates and stones, it is very difficult to work the blade’s full length accurately without wearing notches in the side lands anyway. The third point is it makes no sense to try to grind down the land nearest the neck since the plane of the ura hinges on this land. Best to leave it alone and focus my efforts where they will make a difference.

Plane blades don’t even have a land near the head, so the futility of working the entire ura on plane blades is even more obvious than for a chisel.

Work the Plan

The traditional Japanese tool used to flatten and/or correct ura is a smooth steel lapping plate called a kanaban, meaning “metal plate.” To use it, carborundum powder and water are placed on the plate, and the blade is lapped. This is not a difficult process at all, but there is a tendency for the blade’s perimeter to be ground more than the interior areas as the grit is forced in between the kanaban and the blade’s perimeter. To avoid this tendency, and to speed the process up, I prefer to use diamond plates instead of kanaban.

Whatever plan you developed, and whichever tool you selected for this job, the time has come to work the plan. Do you need more medicine? A bigger coffee cup?

First, color the ura’s perimeter lands with a marking pen or Dykem to help you see where the ura is being ground down. Don’t ever guess.

Place the most pressure on the focus line selected above. Move the blade back and forth (not side to side) onto and off of the diamond plate or kanaban with the cutting edge and the focus line always touching the diamond plate or kanaban. Don’t go past the high point for now. Be careful to not grind a notch into the narrow side lands where they meet the edge of the diamond plate or kanaban. Most people make this mistake at first.

Grind the ura down so the line at the highest point and the cutting edge is fairly flat.

Work the blade on and off the edge of the diamond plate using short strokes and without going much past the highest point marked earlier. This works because the right and left side lands are thin and can be abraded in just a few strokes. I have moved my fingers to reveal the lines, but in actuality my fingers will press down hard on the focus line while working the blade.
Using a stick to apply more pressure to the blade. I am holding the end of the stick and the chisel’s handle together in my right hand. This is simply illustrating a technique. This chisel did not actually require this sort of aggressive attention.
The same stick technique works even better for plane blades and makes it easier to apply pressure right behind the cutting edge. When doing this, however, be sure to work the blade both forward and backward while moving it right and left on and off the plate’s edge to avoid digging a trench in the narrow side lands.

Remember, the narrow lands at the sides of the hollow-ground urasuki will abrade down quickly. And the rest of the ura can be gradually flattened during subsequent sharpening sessions using regular sharpening stones. It doesn’t need to be made perfect immediately. What matters most is the steel on the land right at the cutting edge.

The high spot on the land near the top of the photo has been relieved after a few passes on the #400 diamond plate. The side lands are in fair condition, and the land behind the cutting edge (itoura) needs just a little more work.
After a few more passes on the diamond plate, the ura is in good shape. Note the land at the photo’s bottom is not in full contact, but the opposite side is. This is will not impact the blade’s performance, and will work itself out during future sharpening sessions without special attention.
Flattening my stones before using them. Notice I am using two 1,000 grit stones to save time and stones. Don’t neglect flattening your stones, whether you use waterstones, novaculite stones, coticule, or even sandpaper.
Working the ura on the flat 1000 grit waterstone. Did I mention it is flat? Notice that I am working on and off the stone, not side to side, to save the right and left lands. Some but not all strokes are full length. The goal is simply to remove the deep scratches left by the diamond plate.
The ura after polishing on the flat 1000 grit waterstone. At this point the ura is in good shape. Notice how the land at the photo’s left is wider that elsewhere. This increase in width developed because this location was the high spot on this convex ura. Notice how the land on the left side is not even touching the plane in one area. What you should take away from this photo is the realization that if I had focused my efforts on this high location first and ignored the downward curvature of the land nearest the cutting edge, I would have wasted a lot more time and valuable metal only to shorten the useful life of this excellent chisel. Do you see the benefit of carefully checking the ura’s condition, making a plan with clear goals and objectives, and then working the plan? Did the medicine work? Next, we’ll work on the bevel, make a tiny burr, polish it off by making a few strokes alternating from bevel to ura, and be ready for the finishing stone.
Working the bevel on the flat 1,000 grit waterstone. Notice the mud piling up in front of the blade indicating the extreme cutting edge is in contact with the stone. I am applying pressure only on the push stroke to prevent the stone from rocking and developing a “bulging bevel,” A honing jig is not necessary.
The bevel after working on the 1,000 grit waterstone. No jigs were used. No “tricks” involving rulers were used. A silly, inefficient “micro-bevel” was neither wanted nor needed. The bevel is perfectly flat. Flattening the ura and polishing both ura and bevel to this level took less than ten minutes. When the purchaser of this blade eventually dulls the edge, he should not need to spend more than 2~3 minutes to sharpen this blade once his gear is ready, assuming he is able to sharpen freehand.

Polish a blade’s ura up to the level of your finest finishing stone once, and don’t touch it with rougher stones again unless it is absolutely necessary, or further gradual flattening is required. This means that in normal sharpening sessions you must remove all the damage at the cutting edge by abrading the bevel with the rougher stones, and only when the bevel is ready for the finish stone, do you work on the flat or ura, alternating from bevel to flat/ura until all defects, burrs, and even visible scratches are polished away.

If you condition the flat (ura) side of the blade correctly, and keep it polished, you should not need to work it on anything but your finish stone until it is time to tap out and grind the ura or back in the case of plane blades. Therefore, the bevel side of the blade is where we spend most of our time and effort.

Now that the ura is in good shape, we will look at sharpening the other side of the wedge, the blade’s bevel, in the next post in the series.

YMHOS

Links to Other Posts in the “Sharpening” Series

Sharpening Japanese Woodworking Tools Part 1

Sharpening Part 2 – The Journey

Sharpening Part 3 – Philosophy

Sharpening Part 4 – ‘Nando and the Sword Sharpener

Sharpening Part 5 – The Sharp Edge

Sharpening Part 6 – The Mystery of Steel

Sharpening Part 7 – The Alchemy of Hard Steel 鋼

Sharpening Part 8 – Soft Iron 地金

Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

Sharpening Part 10 – The Ura 浦

Sharpening Part 11 – Supernatural Bevel Angles

Sharpening Part 12 – Skewampus Blades, Curved Cutting Edges, and Monkeyshines

Sharpening Part 13 – Nitty Gritty

Sharpening Part 14 – Natural Sharpening Stones

Sharpening Part 15 – The Most Important Stone

Sharpening Part 16 – Pixie Dust

Sharpening Part 17 – Gear

Sharpening Part 18 – The Nagura Stone

Sharpening Part 19 – Maintaining Sharpening Stones

Sharpening Part 20 – Flattening and Polishing the Ura

Sharpening Part 21 – The Bulging Bevel

Sharpening Part 22 – The Double-bevel Blues

Sharpening Part 23 – Stance & Grip

Sharpening Part 24 – Sharpening Direction

Sharpening Part 25 – Short Strokes

Sharpening Part 26 – The Taming of the Skew

Sharpening Part 27 – The Entire Face

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or profitably “misplace” your information.

Matsui Seimitsu Precision Squares

Maestro Bruno Walter 1876~1962

By concentrating on precision, one arrives at technique, but by concentrating on technique one does not arrive at precision.

Bruno Walter

We would like to introduce some excellent tools made by a company called Matsui Seimitsu Kogyo located in the city of Sanjo in Niigata Prefecture in Japan. We have been using this company’s products for many years and have started carrying a few by popular demand. The time has come to share these with our Beloved Customers in general.

Matsui Seimitsu Kogyo translates to “Matsui Precision Industries,” but I’m just going to call them Matsui Precision. The company has been around for over 100 years. They may not be the largest manufacturer of precision tools in Japan, but their reputation is unsurpassed.

Allow me to digress for a moment while I grind these oak galls to make some ink. Just about out, you see. Anyway, as you can probably tell from my posts to this blog so far, and which will become even more obvious in the future, I love ancient tools and learning how beautiful work was done by determined people using basic, even crude tools. But I am also fond of excellent refined handtools that help me do a better job more efficiently. I am always on the lookout for such tools, and this post is about one such tool I discovered. One thing I like about this tool is that while it is essentially unchanged from the days when Noah was knee-high to a grasshopper, Matsui Precision has subtly improved the ancient and lowly square in ways that are not immediately obvious. For one thing, it really is a “Precision Tool,” even though you wouldn’t think so just by looking at it.

The idea of using “precision tools” for woodworking is offensive to some. I have seen online discussions of precision tools induce psychotic events in some amateur woodworkers. Perhaps the thought of such tools triggers hallucinations of digital micrometers swooping through their dreams while pissing down on the eternal beauty flowing from their masterful hands. Or perhaps they imagine the smelly poor-quality Chinese-made tools they buy in bundles from Harbor Freight to be more expressive than the cold precision tools of the sort less artistic machinists use. To the former I say “Don’t drink alcohol with your medications.” To the latter I exhort: “Extract your head from your nether regions and behold the light of civilization!” 

Anyway, that’s enough ink to last a month, so enough free psychoanalysis. Let’s get back to Matsui Precision Squares.

They have six distinct advantages over almost any other simple square you will find:

  1. Precision: Unlike any square ordinarily available to woodworkers, these are manufactured and certified in accordance with Japan Industrial Standards (JIS). The relevant standard is JIS B7516 (2005). The hardened steel model (SY Series) is rated Grade 1, and the graduated model SM Series) is rated Grade 2. Accordingly, these squares precisely measure 90°. Without using other precision instruments the only way to confirm this claim is with another high-precision machinist’s or diemaker’s square. The MP square will pass this test, not to woodworking tolerance, but to machinist’s tolerances. We guarantee it.
  2. Lightweight and Handy: You will not find a precision square lighter or handier. The blade (long leg) and stock (short leg) are relatively thin, light in weight, and handy to use, unlike machinist’s squares and combination squares with their thick, heavy, clumsy, flat stocks and blades which make it difficult to see light showing between them and the workpiece. The Matsui blade is relatively thin making the square easy to use for woodworking.
  3. Durable: The stock and blade of both SY and SM series tools are joined by spot welds, unlike all but the most expensive machinists squares; Not a compression joint, not glued, not bolted, not pinned. They are not indestructible, of course, but the stock or blade will bend or melt before this connection fails.
  4. Corrosion-Resistant: both blade and stock are stainless steel so they won’t rust even if used and stored in constantly humid conditions, even if you have sweaty hands.
  5. Hardened: This feature is most important in my opinion. The blade and stock of the SY series squares are hardened, a very unusual feature. For the woodworker, this means that the blade will better endure the scraping and shaving action of steel scribes and heat-treated marking knives used in layout and stay straighter much longer than all but the most expensive machinist’s and diemaker’s squares.
  6. Relief Cut: The stock has a small half-circle notch cut into where it meets the blade to prevent wood shavings etc. from jamming between the blade and/or stock preventing them from making clean contact with the workpiece ruining accuracy, an important detail indeed.

In short, the Matsui Precision square will help you do better woodworking, easier, and for many years.

We carry two models of Matsui Precision squares. The first is the SY Series pictured below, with a hardened stainless steel blade but without graduations. The stock is hardened to Rc54~57 and the blade to Rc48~52. This is the tool we use and recommend for layout using a marking knife.

The SM series is different from the SY Series in three ways, reflected in the lower price. First, the blade is not hardened. Second, it has deeply etched graduations (not laser etching) which are perfect for using with a scribe or marking knife because the tool’s tip can get into the graduation for positive indexing. And third, the level of precision is one level lower at JIS Grade 2. The graduations include a √2 scale useful for determining the diagonal distance of a square by measuring a side.

If you are tired of squares that aren’t square, that are bulky, heavy, and clumsy to use, that are destroyed by a single drop, or that get eaten alive by your marking knife or scribe, then you should give these a try. You’ll never look back.

If you would like to purchase one, please inquire using the form below.

Matsui Precision Hardened Stainless Steel Squares (w/o graduations) Model SY-15
Product IDNominal Size (mm)Blade lStock lStock t¥ Price
SY-550524086,270
SY-770725686,270
SY-101001057086,270
SY-151502029986,820
SY-2020025212288,690
SY-252502521481012,320
SY-303003021761015,180
Matsui Precision Hardened Stainless Steel Squares (w/o graduations)
Matsui Precision Stainless Steel Square (w/o graduations) Model SM-10
Product IDNominal Size (mm)Blade lStock lStock t¥ Price
SM-550524083,080
SM-770725683,080
SM-101001127083,080
SM-121201408583,080
SM1515017010083,300
SM-2020022512084,840
SM-2525027514510.56,820
SM-3030032517310.58,800
Matsui Precision Stainless Steel Squares (w/ graduations)

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or conveniently and profitably “misplace” your information.

The Sewari Kerf

If the only tool you have is a hammer, it’s hard to eat spaghetti

The David Allen

You may have noticed sawkerfs cut into the sides of the peeled cedar logs in the pictures in my earlier post about Sotomaru nomi and wondered “what the heck!?” I know that was my reaction the first time I saw similar slits many years ago.

“Sewari Kerf” sounds a bit like the phrase for hello in Thai, but trust me, I know the difference. “Sewari” 背割りtranslates from Japanese to “back split.” Nothing to do with drafty pants.

Notice the sewari kerf in the upper surfaces of the peeled cedar beams in this picture. This will be oriented upwards in the structural frame.
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Three peeled cedar logs joined for a structural frame. Oriented upside down in this photo. Notice the sewari kerfs and the minor cracking. This degree of cracking is acceptable.

You will also notice some narrow cracks in the peeled logs in the photo above. These are natural shrinkage cracks that always occur in timbers that contain the tree’s heart. If sewari had not been cut into the peeled cedar logs in the photos above, the cracking would not be hairline, but would be as wide and wandering and ugly as a politician’s morals.

A sewari kerf provides a predetermined location for shrinkage stresses to collect resulting in a more attractive and structurally sound post or beam. It also makes it possible to use these shiny peeled cedar posts and beams with less waste while achieving a more refined, orderly, reliable appearance.

Allow me to digress a bit while the ink dries.

The Japanese consumer places high value on uniformity of appearance even in natural materials. This is also why Japanese ladies will pay $120 for a perfect musk melon as a gift for someone knowing it won’t taste any better than a less-beautiful but still expensive $20 melon. Both giver and receiver understand and appreciate the sentiment inherent in such a gift beyond the melon’s taste.

A Father’s Day gift in a wooden box
 (102058)
Peeled cedar logs awaiting purchase at the Meibokuya warehouse. These exposed structural timbers are expensive and will be wrapped in foam and cardboard and plastic before shipping.

The point: A natural product is made to look more uniformly natural by eliminating all natural defects. Makes perfect sense, right? Welcome to Japan.

Another aspect of this cultural peculiarity can be seen most in the traditional Japanese garden, if you have eyes to see it. Tremendous time and effort and money is spent constructing and maintaining a miniature representation of the natural universe in a small space. In this case, not uniformity but exaggerated naturalness is the goal. While the ostensible goal is the appearance of natural growth and random placement of features, there is not a single natural or random thing to be found in a Japanese garden, except perhaps the water in the pond. A beautiful art form to be sure. A triumph of design and patience. But about as natural as most movie actresses nowadays.

Kutsura Rikyu Garden

The sewari kerf too is not natural, but it helps nature appear both more natural and more uniform. It is also better for the environment. Did someone just say “Poppycock?” Ah. In that case, let us reason together, Gentle Reader.

The sewari makes it possible to cut square posts and beams from smaller diameter trees at less cost and with less waste. Indeed, without the sewari, many millions of small trees that would otherwise be clear-cut to make room for roads, infrastructure, and development, then chipped and tossed aside on the forest floors of Japan to return to the soil and atmosphere, can instead be used for construction lumber.

This wasteful activity is common throughout the entire world and has a tremendously harmful impact on the atmosphere, soil erosion, and water quality. Sewari is an environmentally-friendly way to make more efficient use of the world’s most environmentally-friendly building material.

Please encourage wood producers and governments in your area to develop and employ better ways to use and maintain forests, because neither thoughtless harvesting focused solely on profits, nor abandoning forests to burn and rot and release particulate and chemical contaminants into the atmosphere and destroy animals and their habitats in the process, is responsible stewardship. We need the building materials, oxygen, and carbon dioxide entrapment capabilities of forests now more than ever. Bambi needs a home and dinner too.

I see the ink has dried so I will step down from my soapbox now (Oops, I almost tripped and broke my fool neck!).

Back to the subject of this post, please take a gander at the photos below of two square construction-grade Akita Cedar posts, both with hearts in their centers. The one on the left does not have a sewari cut, but it does have a nasty collection of shrinkage cracks. Ugly, oh sooo ugly. The one on the far right has a sewari cut, but only a couple of tiny shrinkage cracks. If you had a choice, which one would you buy? Which one do you think is more dimensionally stable? Which one is a more efficient use of natural resources?

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A beautiful Hinoki post with sewari cut and dimensioned to final width and thicknes and marked with location and orientation in the building. Notice how the kerf is narrow near the center and widens towards the timber’s exterior. This began as a simple sawcut with parallel sides, but as the wood dried and shrunk, the kerf spread into a V shape. The timber’s dimensions distorted accordingly, so this timber was trued to this final dimension after the shrinkage and internal stresses calmed down.

Japanese building codes, especially those governing wooden construction, have changed a great deal since the Great Hanshin Earthquake of 1995 mandating metal connectors in tension loading, and metal plates spanning many connections in wooden structural frames. To accomodate the sewari kerf, manufacturers of these structural connectors have developed extra-wide plates that span the kerf, with screws and nail holes offset from the centerline. The point I am trying to make in my meandering way is that sewari is now an integral but hidden part of public and private life in Japan.

Perhaps the sewari kerf looks unsightly. In the case of posts, the carpenter will orient it away from view as far as is reasonable. In the case of beams, he will orient the kerf upwards out of sight.

Sometimes, after the wood has reached equilibrium moisture content and internal shrinkage stresses have calmed down, the carpenter will glue a strip of wood into the sewari kerf to fill it. Sometimes this strip makes the member look better, sometimes it makes it look worse, especially when it pops out and flops around. What do you think?

In the top left-hand image a sawkerf is made in wet wood. As the wood shrinks, the kerf opens and the walls inside the kerf often develop a curvature. These surfaces must be trimmed straight after the wood reaches equilibrium moisture content. A wedge-shape strip of wood is then glued into the kerf. All four sides of the wood are then trued. This is an extreme example.
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リフォーム改修用語 背割り埋め

In conclusion, I would like to add a few points of clarification and a real-world example from my long-list of screw-ups.

Sewari doesn’t usually add strength, but it makes it possible to use less than ideal timbers, and to process those timbers, including reducing the moisture content to allowable limits, in a shorter period of time and with much less waste than would otherwise be possible. This is a big deal if you care about conservation of natural resources. It’s also a big deal if you are concerned about the cost of materials.

So long as the kerf can be oriented away from view, the appearance of timbers with sewari is a heck of a lot better than those without. And have you ever noticed how customers will look aghast at wandering, gradually widening shrinkage cracks in a large timber post or beam imagining that it will cause the member to eventually fail? Of course you have.

I did one job in Nevada, the driest State in the USA, using many large and long square timber posts that developed shrinkage cracks after they were installed. The cracks alarmed the Client so badly they insisted they would not occupy the building unless we installed metal straps at three heights around the posts to ensure they wouldn’t explode, when in truth the timbers were not expanding but rather shrinking, and the cracks did not impact the posts’s strength or resistance to buckling to any significant degree.

But if we had cut a sewari kerf into those posts immediately when they arrived at the hot dry desert jobsite, the amount of shrinkage would not have been less, but that shrinkage would have concentrated at the kerf and not caused the Client to make illogical, pointless and expensive demands. On the other hand, if cosmetics had been a priority, the Client would have been right to object to those ugly cracks, not that straps would have made any difference.

So I put it to you, Gentle Reader, did we save money on that job by not taking the time to cut sewari kerfs and consequently being forced to spend money and time fabricating and installing silly metal straps to resolve the Client’s complaints later, invalid though they may have been? I think not.

Go forth and do better, my son!

YMHOS

kitayamasugi-5
A well-managed cedar forest in Japan

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or conveniently and profitably “misplace” your information.

Sharpening Part 19 – Maintaining Sharpening Stones

砥石の面直しについて :鑿研ぎ練習 番外編_e0248405_17182931.jpg

Give me six hours to chop down a tree and I will spend the first four sharpening the axe.

Abraham Lincoln

Sharpening stones must be maintained if they are to perform effectively. Abe Lincoln’s quote above is especially relevant to this subject.

There is a lot of hogwash taught as holy gospel on this subject, so in this post I will suggest some more or less traditional methods that I know both work well, and are cost-effective. Do with them as you will.

Key Principles

Let’s begin with a few basic but critical principles for sharpening:

  1. For the majority, but not all, applications, your blades need to meet the following standards:
    • Flat back/ura: perfection is not necessary but it must be flat enough for you to be able to consistently work the steel directly behind the cutting edge on your finishing stone;
    • Flat bevel, for same reason mentioned above;
    • Straight cutting edge (except when a curved cutting edge is required).
  2. All Stones get out of tolerance with use. Working a steel blade on a sharpening stone of any kind, whether waterstone, novaculite, coticule or carborundum, wears the stone a little bit with each stroke, creating a dished-out, twisted surface to one degree or another, even if you can’t detect the distortion with Mark-1 eyeball. Therefore, you need to frequently check and periodically true your stones;
  3. Despite what many imagine, a hollowed-out stone cannot reliably maintain a blade with a planar ura, a flat bevel, and a straight cutting edge, but it can damage the blade being sharpened.

The Rule of Seven applies, so reread these three critical points three times, click your heels three times, and ask the gods of handsaws to help you remember them.

Albrecht Dürer - Melencolia I - Google Art Project ( AGDdr3EHmNGyA).jpg
Melencolia I by Albrecht Dürer 1514
What is the angel pondering? Sharpening, no doubt.

Pretty simple stuff, right? I apologize if you already know these things, but you would be surprised how many people know them but still ignore them, and then wonder why their blades won’t behave. Iron Pixies? Nah. Perhaps Mifune Toshiro said it best in Akira Kurosawa’s movie Yojimbo when he quoted the old Japanese proverb: “There’s no medicine for foolishness” (馬鹿に付ける薬はない).

Toshirô Mifune in Yôjinbô (1961)
A scene from Akira Kurosawa’s classic movie Yojimbo (1961), the inspiration for the later spaghetti westerns beginning in 1964 and even the more recent TV show The Mandalorian. In this scene, the nameless loner anti-hero is warning off some ruffians who have bragged about their tattoos and the death sentences hanging over their heads and informed him they aren’t afraid of him or the pain of being cut. The hero responds with the proverb “There’s no medicine for a fool,” then tests their resolve by cutting 3 of them. Ouch! A hard lesson easily avoided. BTW, if you have tattoos and visit Japan, best to keep them covered since they have an old and indelible association with criminal organizations and judicial branding.

Here’s the scene on YouTube. Please don’t watch it if you are squeamish. Never call the Man With No Name’s bluff.

Yôjinbô (1961)
The Man With No Name (aka Kawabatake Sanjuro played by Mifune Toshiro) pondering the interesting financial opportunities awaiting him in the troubled little post town. His older swordsmith friend (Tono Eijiro) bitterly objects. He was right.

Although it has only happened once or twice in my recollection (my saintly wife of the jaundiced eye may disagree (ツ)), on those few occasions when I have made a stupid mistake I have been known to ask subordinates to go buy a large bucket of “Idiot Salve” for me at the drugstore. The jury is still out on the effectiveness of this ointment, but I would like some credit for writing this entire article without using it.

But I digress.

Obviously, if every stroke wears the stone a little, then we must constantly check our stones with a stainless steel straightedge for flatness (length and width) and wind (diagonals) as we use them. It takes 5 seconds. Even if your stones are brand new, you may find distortions. Time spent checking is not wasted if it results in improvement. This is the heart of quality control, and is applicable to everything in life.

Truing Stones

When your check reveals the stone is out of tolerance, you need to flatten/true it. Don’t put it off. There are many ways to get this job done. Some people advocate using diamond plates to flatten stones. Others insist that sandpaper is best. And then there are the specialty flattening stones. It ain’t rocket surgery. All these methods work, but are unnecessarily costly and time consuming in my opinion. The following is the procedure I use and recommend. Give it a try, Gentle Reader, before you dismiss it.

  • Always have two of each of your rougher stones soaked and ready to go when you start sharpening. This means 2 – 1,000 grit stones, and 2 – 2,000 grit stones in my case. If you use your tools, owning these extra stones is never wasted money.
  • If the blade is damaged, for instance chipped or dinged, begin with a rougher stone or diamond plate, whatever you have that will waste metal quickly and easily while keeping the blade’s bevel flat.
  • If your blade is not damaged, begin the sharpening process with a fresh, flat stone, for instance 1,000 grit. Turn the stone end-for-end halfway through the estimated number of required strokes and continue sharpening. Yes, you need to keep track of your strokes, at least approximately. This will become second nature with practice.
  • Occasionally check the stone for dishing and wind using your stainless steel straightedge. With practice you will develop a sense of the stone’s condition without the need to use a straightedge. Stop using the stone when the distortion becomes noticeable. 
  • Switch the distorted stone with your flat stone of the same grit and continue sharpening. 
  • When both stones become distorted to the same degree, cross-hatch the faces of both with a carpenter’s pencil, then rub them against each other under running water if possible, or while frequently adding water if not. Make short strokes and be careful to apply even pressure to the stones . This requires self-control and is more difficult than it sounds until you get used to doing it. The friction and water will wear the high spots down.
  • Switch the stones end-for-end frequently to ensure the stones wear evenly. Monitor the pencil marks to track progress.
  • Check with a straightedge frequently, and stop when both stones are flat, or maybe even a tiny bit convex. 

With practice, and if you don’t let your stone’s condition get out of hand, this process should take only a few seconds, but it will ensure you are always working on flat stones.

If you think this technique is slower than using a diamond plate, specialty flattening stone, or sandpaper, you are overlooking a key point, namely, that it makes it possible to flatten two stones at the same time with the same hand movements. It may be slower than flattening a single stone with a diamond plate, but it is definitely quicker than using the same diamond plate to true two stones one at a time. Think about it.

It’s also cheaper because diamond plates are costly, and wear out. The specialty flattening stones are not cheap, and they too wear out. Both methods can contaminate stones, in my experience. And sandpaper wears out quickest of all and is the most expensive method long-term.

Now you have two stones of the same grit on-hand that are flat, free of contamination, and ready to rock-n-roll without wasting time or money on diamond plates, sandpaper, or special flattening tools. This means you have four fresh, flat surfaces at the beginning of the work day to use before you need to take time away from your paying job. And if you pay attention when sharpening, and take care to use each stone’s entire face, the time between sharpenings can be increased while saving significant amounts of cashy money.

Finishing stones seldom require flattening, but the same procedure can be used. A better solution is to the use the float-glass lapping plate described next.

If you need to get a stone extra flat, rub the stone on the  ⅜~1/2” (10~12mm) or thicker plate glass mentioned in the previous post. You can often bum scrap pieces of glass from glass stores or contractors. Dumpster diving behind a glazing shop may prove useful if you are careful and don’t cut your arm off. Don’t forget to remove the sharp corners and edges with a carborundum stone or you might end up like the annoying guy in the video linked to above.

To turn the plate glass into a lapping plate, aggressively roughen one side with a carborundum stone, and clean it thoroughly with a scrub brush, soap and running water to remove every trace of glass and stone particles. Then clean your brush and scrub the glass again. These scratches you just made will turn it into an inexpensive and efficient lapping plate. Trust me. Just wet the glass and rub the stone on it while rinsing frequently. Try to use the entire surface of the plate, not just the center.

If a stone becomes grossly distorted, you can use a rougher stone or diamond plate to true it. Even a concrete sidewalk and garden hose will do the job. However, if you do this, remember that there is no way to avoid contaminating the finer stone with embedded grit from the rougher stone or concrete.

To remove the offending stone particles, scrub the stone’s faces, sides and ends with a rough bristle brush under running water. Finish by polishing the stone’s face with a nagura stone, and rinsing well.

You should also use your nagura stone frequently to dress and true the faces of your finishing stones.

Don’t forget to maintain the edge chamfers on your stones and keep them free of contamination too.

As with all things, moderation is best. A perfectly flat stone is expensive to maintain and not especially better for general woodworking than a pretty-flat stone. Beware! For this rabbit-hole is not only deep, but sleepless nights and gibbering insanity afflict many who strive to reach its darkest depths.

Rough Stone vs. Finer Stone

Here is an important factoid you should remember: A stone trued using a rougher stone or diamond plate will be effectively of rougher grit than its designation until its surface is worn smooth again. And it will wear faster too. But if you use identical grit stones (same brand is best) to true each other, the effective grit of each will remain unchanged.

Reread the last paragraph three times, click your heels three times, and do that prayer thing again. Namu Amida Butsu.

In this post we looked at inexpensive traditional ways to effectively flatten and maintain our sharpening stones long-term. Now that our stones are looking good, in the next post to this little theatre of gleeful mayhem and hogwash refutation we will be ready to consider how to use them to flatten and polish the ura of our blades. Y’all come back now y’hear.

YMHOS

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I don’t want to hear no more of your cracks about hogwash. You said to clean the stones, didn’cha!?

Links to Other Posts in the “Sharpening” Series

Sharpening Japanese Woodworking Tools Part 1

Sharpening Part 2 – The Journey

Sharpening Part 3 – Philosophy

Sharpening Part 4 – ‘Nando and the Sword Sharpener

Sharpening Part 5 – The Sharp Edge

Sharpening Part 6 – The Mystery of Steel

Sharpening Part 7 – The Alchemy of Hard Steel 鋼

Sharpening Part 8 – Soft Iron 地金

Sharpening Part 9 – Hard Steel & Soft Iron 鍛接

Sharpening Part 10 – The Ura 浦

Sharpening Part 11 – Supernatural Bevel Angles

Sharpening Part 12 – Skewampus Blades, Curved Cutting Edges, and Monkeyshines

Sharpening Part 13 – Nitty Gritty

Sharpening Part 14 – Natural Sharpening Stones

Sharpening Part 15 – The Most Important Stone

Sharpening Part 16 – Pixie Dust

Sharpening Part 17 – Gear

Sharpening Part 18 – The Nagura Stone

Sharpening Part 19 – Maintaining Sharpening Stones

Sharpening Part 20 – Flattening and Polishing the Ura

Sharpening Part 21 – The Bulging Bevel

Sharpening Part 22 – The Double-bevel Blues

Sharpening Part 23 – Stance & Grip

Sharpening Part 24 – Sharpening Direction

Sharpening Part 25 – Short Strokes

Sharpening Part 26 – The Taming of the Skew

Sharpening Part 27 – The Entire Face

If you have questions or would like to learn more about our tools, please use the questions form located immediately below. Please share your insights and comments with everyone in the form located further below labeled “Leave a Reply.” We aren’t evil Google or incompetent facebook and so won’t sell, share, or profitably “misplace” your information.