Sharpening Part 11 – Supernatural Bevel Angles

Pixie, kobold, elf, and sprite, All are on their rounds tonight; In the wan moon’s silver ray, Thrives their helter-skelter play.

Joel Benton

Iron Pixies

Beloved Customer, have you ever placed a tool down, only to later discover it has vanished into thin air? Do your tools ever become inexplicably dull or corroded within what seems like just a few days after cleaning and sharpening them? If so, you may have an Iron Pixie infestation without realizing it. 

Respected fairyologists theorize that, unlike their timid brethren frolicking in forests, or their blingy cousins infesting Hollywood, New York, and Washington DC who delight in tricking the mass media, film industry and corrupt politicians into constantly making greedy, immoral, lecherous, hypocritical fools of themselves, Iron Pixies (genus Fatum Ferrum), do not fear iron or iron alloys. Indeed, besides pilfering and concealing tools that contain iron, they love nothing more than to use their corrosive powers to return this metal to its natural state through the thermodynamic chemical process known as “rubeum, et conversus abibo” (turn red and go away).

These piratical pixies become especially joyful if the owner of the pilfered tool is unable to find it after much frantic searching and he is eventually forced to buy a replacement. Only when they see the replacement tool will pernicious pixies permit the owner to locate the pilfered tool, usually in a deplorably rusty, chipped and paint-covered condition. Nasty, vicious little pests!

We’ll come back to the supernatural impacts of these maniacal monsters on woodworking tools, but first let’s examine some more mundane details about sharpening blades, and a few things that typically go wrong with them.

The Ideal Bevel Angle

There is such a thing as an “ideal bevel angle” for each blade in each cutting situation, one that cuts the wood quickly, cleanly, with minimum force expenditure and that keeps the blade effectively sharp for the maximum amount of cutting possible, but determining this angle is not an easy calculation since it is difficult and expensive to actually observe what is happening at the cutting edge from a shaving’s-eye-view.

For example, a steep  60° bevel angle on a chisel will support the cutting edge thoroughly and will be durable, but it will pound the wood more than cut it wasting time and energy and damaging the wood unnecessarily. On the other hand, a 15° angle will cut very nicely, thankee kindly, but the blade is certain to chip and dull quickly. A balance is necessary.

This balance will depend on many factors including hardness and abrasiveness of the wood you are cutting at any time (e.g. Sugar Pine versus Ipe), the quality and nature of your chisel blade, the type of cut you are making (low-pressure surface paring versus high-pressure deep mortises), and the care you take to protect the cutting edge. Yes, technique matters.

Determining the ideal bevel angle is ultimately a trial and error process the diligent craftsman will perform until it is second nature, but the following are some general guidelines to get Beloved Customer started.

Most Japanese woodworking tools, including plane blades and striking chisels (oiirenomi, atsunomi, mukomachinomi, etc.) perform well in most construction and furniture woods with the standard 27.5°~30° bevel angle. This is a good compromise, acute enough to cut most wood efficiently without too much friction, while still providing adequate support to the thin cutting edge to avoid chipping. Indeed, this is the bevel angle we insist Beloved Customers maintain as a condition of our warranty.

But as Captain Barbosa advised, these are only guidelines. For example, 35° is often a superior bevel angle for chisels when quickly cutting mortises in harder woods or planes shaving tropical hardwoods.

When cutting very soft woods, such as Kiri (Paulownia Tomentosa), similar to balsa wood, a 22~24° bevel angle may work best, however. 

Paring chisels (tsukinomi), when used properly, are subject to less violent impact forces than striking chisels, and can usually handle a 24° bevel angle. But for most woods, a professional-grade Japanese plane or chisel blade will likely experience chipping if the angle is much less. 

There are many variables and potential solutions one might consider, but your humble servant recommends starting your experiments with a 27.5~30° bevel angle for plane and chisel blades.

If Beloved Customer finds that your blade chips or dulls quicker than you think it should, increase the angle gradually until it calms down. This can result in a double-bevel blade, one difficult to sharpen freehand. In this case, your humble servant fully supports using a honing jig, at least until you achieve a flat bevel wide enough and stable enough to sharpen freehand. But don’t handicap yourself by relying solely on honing jigs forever because they can become like training wheels on a bicycle: slow, awkward and childish.

Mercurial Bevel Migration

There is a strange, almost supernatural phenomenon many woodworkers experience, the first evidence of which is a plane or chisel blade that previously held a sharp edge a long time suddenly and inexplicably dulling sooner than before, or heaven forfend, chipping. Even professionals with many years of experience occasionally see their tools exhibit this nasty behavior. 

Some craftsmen faced with this demonic dilemma begin to question their sanity, even asking themselves: “Has heaven turned its face against me? Where to flee to escape this curse? Do I need a witch doctor or a shrink? Is cranial surgery my only hope?” In past centuries and millennia craftsmen more aware than us modern folk of the dangers of pernicious pixies drew strange hex symbols on their walls or inlaid stone or brass circles and pentagrams into their floors to exorcise them from their workshop. No, the origins of those floor decorations are not just decorative, indeed they have a long history in Europe and America of fending off supernatural pests and bad juju.

Unfortunately, more than one blacksmith has been falsely accused of poor workmanship when the fault actually lay with the tool’s owner unwittingly allowing Iron Pixies to run amok. If this happens to your tools, please use the methods described below to purge any pestilent pixies within the perimeter of your woodworking palace.

Beloved Customers would be wise to consider all possible causes of Mercurial Bevel Migration (MBM), including those unrelated to any infernal fiends that may or may not be skulking in your lumber stacks.

But if not pesky pixies, what else could cause this maniacal metallurgical malfeasance?  Never fear, Beloved Customer, there is another possible explanation, one that can be resolved without drilling holes in one’s skull, or paying for years of expensive psychotherapy, or consuming mind-altering mushrooms, or conducting stinky ceremonies involving burning sage and spirit drums, or placing small bowls of blood and milk around your workshop, or enduring the pain of tattoo needles, or even the simple ritual described in the postscript below.

The more likely cause is simply that it’s human nature when sharpening chisels and plane blades with their tail-heavy construction to apply more pressure to the bevel’s rearward half (farthest from the cutting edge) abrading the softer iron jigane body more than the harder high-carbon steel cutting layer. Eventually, as the soft jigane wears away, the bevel angle will gradually decrease to the point where the cutting edge loses support becoming fragile and causing dismay.

Once you are aware of this tendency and take preventative measures (and assuming you don’t have an iron pixie infestation), all should be well.

Next let’s examine some measures to get rid of both this bad habit and trixy pixies.

Pixie Predation Prevention & Pacification

If you suspect the presence of iron pixies, you should perform the Covington Pixie Detection Test (CPDT). A reliable method is described in the next section below.

In any case, and because prevention is better than Prozac, you should begin your efforts by creating a workshop environment unfriendly to pixies. The following is a partial list of measures your humble servant has found to be effective.

1. Cleanliness: Clean bench surfaces and sweep the floors daily. Vacuum and wet-mop workshop floors at least twice a year during the winter and summer solstices (approximately June 21 and December 21);
2. Add more lighting: Iron Pixies fear light because it reveals them to their enemies;
3. Keep a pair of boots near the door into the workshop: Pixies are deathly afraid of boots, especially when they contain the feet of sharp-eyed human children, but just the sight of boots will usually prevent them from entering a space;
4. Keep brass benchdogs in your workshop. Expert fairyologists insist, and I agree, that having a brass bench dog (remember, Iron Pixies do not fear iron or steel or even the IRS) or two on hand will repel Iron Pixies to the workshop’s dark recesses and keep their nasty claws away from tools. The deterrent effect of bench cats is unclear, but if you decide to rely on one, be sure it bothers to stay awake;
5. Welcome spiders: Although this may seem to contradict No. 1 above, Iron Pixies fear spiders, especially daddy longlegs, who delight in tangling them in their webs and tickling them to expiration.
6. Make regular offerings to the gods of handsaws. More on this subject in a future article.

A more mundane but sure way to prevent MBM is to make or buy and frequently use a bevel angle gauge. This is very important!

Aluminum, stainless steel or even plastic gauges will work of course, but brass or bronze are more effectual at purging perfidious predatory pixies because copper is toxic and zinc gives pixies noisome gas. Be sure to store it close to your valuable steel tools to help repel the vicious little bastards.

Here’s the important thing: Once you have this tool, use it to check your blades during each sharpening session to ensure you are maintaining the correct bevel angle instead of allowing it to decrease incrementally over repeated sharpening sessions. Make this a firm habit. More on this important subject in future posts.

Here’s another important thing: Remember to measure the bevel angle at the blade’s far right or far left edges because the hollow-ground uratsuki of Japanese blades makes it difficult to correctly measure the angle if you check it elsewhere.

Pixie Detection Methods

Iron Pixies are secretive creatures most people never see, but if you suspect you have an infestation, a detection test is called for.

While there are many proven methods to test for pixie infestation, the least expensive non-toxic method to test for pixie infestation is the Covington Pixie Detection Test (CPDT). The execution is simple, but it requires some skill and confidence in one’s abilities.

To the perform the CPDT, sharpen a plane blade, and while doing so, attempt to “stick it” on the stone as shown in the photo below. This phenomenon is evidence the stone and the blade are in such perfect contact that the suction between the blade and the stone’s wet surface is strong enough to support the cantilevered weight of the blade. It can only be achieved when localized sources of natural chaos, of which iron pixies are a prime example, are firmly under control.

Assuming your blade, stones, and skill level are up to the task, if you are unable to accomplish this marvelous feat even after many attempts, the likelihood of an infestation of peevish pixies nearby is high. In that case, use the preventative measures listed in the section above, or the banishment ritual described in the postscript below. You should also flatten your sharpening stones (especially the rough and medium grit stones) and make sure your blade’s bevel is perfectly flat, for bulging bevels are the pernicious pixie’s playground. (Aha! Iambic pentameter!)

Fair warning: If you stubbornly persist in your efforts to “stick” a plane blade before purging the area of pixies, they may go berserk to prevent this sublime event from occurring. If that happens, Katy bar the door!

In the next stage of our adventure, we will examine some of the health ailments blades commonly suffer.  High cholesterol in chisels? Planes with pneumonia? Or just toolish hypochondria? Stay tuned to find out more.

YMHOS

Postscript: Pixie Catch-and-Release

A few tender-hearted Beloved Customers and Gentle Readers, sick and tired of their precious tools rusting to dust and being stolen, have asked your humble servant for advice about live-catching the Iron Pixies they sense scuttling around in the dark and dusty places of their workshop and then releasing them back into the wild. I can only share my meager experience.

While the concern gentle souls have for the welfare of natural creatures is laudable, it is decidedly misplaced because pixies are not natural creatures like squirrels, cows or even tax collectors (there are some who contend the later are closer to trolls than natural beings, but that is a scurrilous rumor promulgated by tax accountants). But I digress.

Gentle Readers should note that Iron Pixies are not natural beings, but rather supernatural creatures from the land of Faerie that choose to leave their native plane of existence to inhabit workshops in our mortal world for the simple malevolent joy of ruining iron and steel tools and inducing mental anguish in mortals. We may catch them and we may crush them, but few have the ability to banish them entirely from our world, contrary to the claims of The Learned Society of York Magicians, the only documented exception being Mr. John Uskglass and perhaps, it is rumored, an obscure magician named Mr. Jonathan Strange.

My point is that, since we mortals have no access to the supernatural environment from whence pixies hale, we cannot “release” them back into their natural environment at all, but can only strive to make our workshops less attractive places for them to pursue the malevolent mischief they love.

Your humble servant has not researched all methods of trapping pixies and so can offer no certain advice. However, if you are determined to design and deploy such a live-trap, remember that iron pixies are exceptionally clever and can easily avoid and certainly destroy most any trap, especially if it has metal parts.

Bench cats have been known to frighten pixies away, but most are just too damn lazy to keep at it. And no matter how you cook them, and regardless of the hot sauce used, iron pixies always taste like old garbage dumpster wheels and are almost as hard to chew, so scrumptiousness is never sufficient incentive for our feline masters.

I have experienced moderate success banishing iron pixies from my humble workshop, at least temporarily, using a combination of the techniques listed above and the following ancient ritual.

To perform a pixie banishment rite, you will need a few things, chief of which are at least one small, quick, sharp-eyed, strong-lunged child that still believes in Santa Clause, and a pair of large, leather work boots. Never steel-toed boots, mind you, no steel at all!

The more children the better. You may need to borrow boots from friends and family. Don’t forget the Santa Clause thing.

Open one door leading directly to the outside just a crack. Not too far, only 1~2 inches.

Help your sharp-eyed children put the boots on their little feet in your workshop where the pixies can observe (this forewarning visibility is important), being sure the boots can’t accidentally slip off.

Direct said child (or children) to march around your workshop in three circuits widdershins (counter-clockwise) while stomping their boots loudly and screeching “Pixies Flee!!” (ear protection may be necessary).

Have each circuit end at the partially-open door or window whereupon each child should toss a small piece of steel or iron, such as a nail, screw or nut, through the opening while shouting this same spells as loudly as they can.

You should lead the way and set the example, of course.

Nothing scares pixies as much as small children stomping close by in big boots while screeching loud magical commands. Seeing iron or steel then fly through an opening to the outside will usually drive them away.

A word to the wise: Incentive must be provided to the child (or children) for the ceremony to succeed because, as Jeffy Chaucer famously wrote: the “Labourer is worthy of his hire.” Chocolate or other sweets work fine. The child’s mother may object to this form of incentive pay, but carrot sticks provide neither sufficient energy nor adequate motivation to small children in my extensive experience. Besides, who ever heard of fruits and vegetables helping magic? Codswallop!

All the same, best to do it when Mom is away if you think she might degrade the ritual through nagging about nutrition or cavities.

Some Faeriologists have suggested that a variation of this ritual is also effective at driving hidden monsters from under beds and out of closets in residences. Indeed, such a ceremony has been an annual traditional ritual in most households in Japan since ancient times.

For banishing demons and monsters from living spaces in the Japanese tradition, open all doors and windows during daylight hours on February 4th, and, while screaming “Demons Depart!!,” members of the household, including children of course, should each toss a handful of dried beans through each open door and window to the outside, closing them tightly afterwards. Apparently demons like beans. Boots are not worn indoors in Japan.

Children may be small, but they have an important role in protecting the home and family and your tools too. It’s a father’s duty to let them know it and show them how. And they deserve chocolate.

YMHOS

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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
• Sharpening Part 28 – The Minuscule Burr
• Sharpening Part 29 – An Example
• Sharpening Part 30 – Uradashi & Uraoshi