Category Archives: knives

New Tool For Sale! The M2 Hybrid Paring Knife

Traditionally, leather paring knives either have round or straight cutting edges.  I discuss the advantages and disadvantages of each in this post. I usually use an English style straight blade, but became tired of the fact it could only be used for edge paring. Partially inspired by the rounded corners of a spokeshave blade, I made a couple of other modifications to a standard M2 English style knife so that it can be used for more than edge paring.

A slightly curved cutting edge on essentially an English style knife allows it to scoop out leather, necessary for the spine area, headcaps, and decorative work. The blade is oriented at a 45 degree angle, like an English knife, so right and left handers need to purchase different knives. The corners of the knife are rounded so that the tip or heal will not cut through the skin while performing this scooping action. The tiny secondary bevel allows quick resharpening.

This knife can be used for all types of paring necessary in bookbinding: edge paring, reducing spine and caps, paring deep into a skin (similar to a spokeshave’s action) and even for overall scraping, if you are into that.

M2 Hybrid Knife. Around 8 – 9 inches long, and 1 inch wide. Since the grind marks on the primary bevel go along the length of the blade, the primary bevel is not apparent when looking at the top of the knife. The exact curve of the cutting edge varies a bit from knife to knife.

A lower angle primary bevel cuts down on the amount of time it takes to resharpen the blade, since there is less metal to remove. The 13 degree cutting edge is only a millimeter or two. The disadvantage is that there is not a large enough bevel that you can feel when you put your knife on the sharpening substrate; you have to trust your hands and the angle you are holding it at. This is quite similar to sharpening a kitchen knife by hand. Another advantage of the small secondary bevel is that it can be stropped back into shape very quickly, again because not much metal has to be removed. This is a perfect blade for sub-micron stropping. M2 steel seems easier to strop than A2, for some reason.

Cross section of primary and secondary bevels.

The slightly curved blade creates more opportunity to find a sharp area as the knife dulls, so it can be used longer. Straight blades, as they become dull, don’t seem to bite the leather enough to get started with a cut. The disadvantage is you can’t just rub it back and forth like a standard straight edged knife when resharpening. Stropping takes a slight twist of the wrist, to keep parts of the cutting edge in contact with the strop throughout the stroke.

The rounded areas allow you to work into a skin, for headcaps and the spine. But the shape also allows you to use it like a standard English style knife for edge paring.

The third change is that the tip and heel of the cutting edge are rounded.  This prevents the knife from cutting through the skin when you are working away from the edge, similar to how a spokeshave blade works. In practice, I don’t miss having a pointed, sharp tip. A rounded tip also makes it less likely to dig into your paring surface.

The M2 Hybrid used like a standard English knife for edge paring.

All of these aspects combine to make a sensitive and versatile knife intended for professionals. An analogy for cyclists might be this is more like a track bike than a road bike. This knife, in addition to edge paring, can do most of what a spokeshave can do, albeit with more “workmanship of risk”. If you want the most versatile knife on the market, look no further.

Close up of a piece of goatskin feather pared,, so that the valleys of the grain are cut through. The middle of the blade was used for this, almost parallel to the edge of the leather..

Progressively paring towards the center. The rounded edges keep the blade from cutting through the leather as it stretches.

M2 Hybrid Paring knife. M2 Steel. The handle is hand carved wood, covered with vegetable tanned goatskin, and ergonomically shaped. The metal is .040″ thick, the handle around 5/8″ at the thickest point. It is about 1 inch wide and around 8-9″ in overall length. The secondary bevel is 13 degrees.  Hand sharpened to .1 micron.

The M2 Hybrid Paring Knife.  $250.00.  Order here.

Small M2 Hybrid knife. The best knife for onlays and intricate leather decorations. Also great for paring paper. M2 Steel. The metal is .025″ thick, about 5/8″ wide and 6-7″ long. Leather covered wood handle. The  secondary bevel is 13 degrees. Hand sharpened to .1 micron.

The Small M2 Hybrid Paring Knife.  $150.00.  Order here.

Small M2 Hybrid knife bottom left, regular size next to it.

Twelve Ways of Testing Knife Sharpness

1. Visual inspection. When looking directly at the blade edge, with a light source behind you, are there any reflections? If so, these are dull, bent or chipped areas. The cutting edge should be an almost invisibly smooth black line.

2. Visual inspection, with magnification. When looking at the side of the blade, the smoother it is, the sharper it is, and presumably the longer the edge will last. Brent Beach, for example, measures wear in terms of pixels in a microscopic image at 200x. Leonard Lee’s Complete Guide to Sharpening has a number of electron microscope images of blade edges. Take heart, though, even a “sharp” edge will look like the Rocky Mountains if enlarged enough.

3. Shave a few hairs on your arm. If it is sharp enough to shave, it is probably pretty good. WARNING: THIS IS DANGEROUS

4. Rest the blade on a pen held at a 15 degree angle. If the blade, with just the weight of the knife catches the plastic, it is sharp. If it slides off, it is dull. The closer to parallel the pen and the knife are, the sharper the blade is.

5. Do this same test holding the blade and GENTLY and see if it catches on your fingernail.  WARNING: THIS IS DANGEROUS.

6. Tsujigiri. This test likely seems a myth. Supposedly, at one time, samurais tested their swords by the number of torsos they could cut through in one stroke. The sharpest one was a #5. WARNING: THIS IS DANGEROUS, IMMORAL AND ILLEGAL.

7. For kitchen knives, see if they can penetrate a tomato or onion, with no downward pressure and no sawing. There are many variables in the toughness of the skin of a tomato though, I imagine.

8. Longer blades can be tested by slicing paper, even toilet paper. There are many youtube videos of this. Slicing cardboard, because of its consistent and abrasive nature, is often a field test of edge durability.

9. Feel the edge ACROSS THE BLADE with your finger, applying virtually no pressure. The smoother it feels the sharper it is. You should be able to feel any slight irregularities, indicating  a dull area. WARNING: THIS IS DANGEROUS.

10. Test it on a difficult to cut substrate like styrofoam, cork, or balsa wood.

11. Send the knife to CATRA. They will qualitatively test for initial cutting performance, edge durability, and edge geometry. This will, however, dull your knife, so it is designed for production samples.

12. Possibly the best test is just to use it. Providing you are familiar with the material you are using it on, you can often tell instantly if it is sharp depending on how much force you have to apply.

New! Redesigned 151 Spokeshave for Leatherwork with Shaving Collector

modified 151 spokeshave

Modified 151 Spokeshave with shaving collector. It also makes a convenient stand when flipped upside down.

modified 151 spokeshave2

Note that the shaving collector does not interfere with thumb or forefinger placement.

English trained bookbinders often use a modified spokeshave for long shallow bevels on the turn-ins, reducing the thickness in the spine area of a full leather binding, preparing a new piece of leather for rebacking, and for beveling binder’s board.

I’ve improved the modified Stanley 151 spokeshave that I make and sell by adding a shaving collector. I first saw this on a spokeshave  James Brockman was using in 1990. I can’t quite explain why it has taken me so long to get around to making one for myself — I’ve been busy??? He kindly shared details of the design with me, and mentioned he first saw this while working at Roger Powell‘s shop in the late 1960’s or early 1970’s.

The shaving collector really speeds up work with the spokeshave, since you don’t have to stop and clean off stray shavings every couple of minutes, and they don’t get trapped under your leather, which can cause tearing or holes. Additionaly, it is easy to dump the full collector into the trash.   More information about spokeshaves for leather.

Other modifications to the spokeshave include: reducing the effective cutting angle by grinding the base, truing the adjustment knobs, rounding and lessening the surface area of the sole, opening the mouth, flattening the blade bed by filing and filling with epoxy, flattening the blade cap, and replacing the thin chrome vanadium original blade with a Lee Valley PM-V11 one. This blade is reground to a lower angle, sharpened, and the corners slightly rounded to prevent ridges formed in the leather. All of these modifications make the spokeshave a much more precise instrument and reduce chatter

Even if you rough out the leather with Scharffix or Brockman leather paring machine, this spokeshave can quickly help reduce the ridges and unevenness the results from overlapping cuts and blade changes if you are working on large pieces. It is also essential for gradual bevels wider than the width of a double edge razor blade. And it is a lot of fun to use.

MODIFIED 151 SPOKESHAVE: $275.00     How to purchase


Possibly the Most Specialized Blade in the World

Spyderco makes a number of similar, smaller rescue blades primarily for EMT’s to cut people out of their seat belts in car wrecks.  This blade is used to free trapped whales from fishing lines. It apparently attaches to a pole.

I really need one.

Has Anyone Else Ever Wondered What the Inside of a Board Shear or Guillotine Blade Looks Like if You Saw Through the Mild Steel, Grind the Cutting Edge and Break the Area Where They Are Joined Together?

Peachey’s Ten Commandments of Sharpening

1. Thou shalt not round the bevel or the back.

2. Thou shalt not use jigs.

3. Thou shalt look at the scratch patterns in the metal.

4. Thou shalt use a bevel angle appropriate for the knife and task.

5. Thou shalt not covet thy neighbors knife.

6. Thou shalt sharpen side to side.

7. Thou shalt use a grit progression and entire surface of the stone.

8. Thou shalt not let thy sharpening system become glazed over.

9. Thou shalt not advance to the next grit until the burr develops.

10. Thou shalt not insult thy neighbor by insisting on the absolute superiority of any technique or system.



[1] Rounding the bevel, or the back, is the most common mistake in sharpening.  Though the knife may look ‘sharp’– ie. polished– it will not cut if the included angle becomes too obtuse. Even with careful stropping, eventually the knife will need to be reground and resharpened. A back bevel works fine as long as the included angle is within the desired angle. In practice, a small amount of rounding always occurs when sharpening and stropping: the goal should be to minimize it.

[2] Not relying on jigs will give you much more freedom, and speed, in sharpening a variety of tools.  Many bookbinding knives do not fit it standard jigs, which are often designed for woodworking tools. The hand motions and muscle memory necessary to sharpen freehand is often very similar to the skills necessary to use the knife properly. Throw away your crutches and walk!

[3] Looking at the visual evidence of what you are doing when sharpening is paramount. Even slightly changing the angle of the knife when moving to a finer grit will show exactly what the new grit is doing.  A 10 power magnifying lens is very revealing. Always sharpening in the same direction will disguise the effects of the new grit, often resulting in an unpleasant surprise when a final stropping reveals many deep scratches.

[4] Always use the lowest possible blade angle for the task at hand. For paring leather, this is around 13 degrees.

[5] Knives are very personal.  You need your own, and get to know how to use and sharpen the particular angles it develops.  Most people sharpen with small idiosyncratic deviations from a geometric ideal, and learn to work with these deviations in practice. A well made knife will last the rest of your career, don’t purchase or make an inferior one. In the bookbinding world, it is a major faux pas to borrow a colleague’s paring knife — don’t be a rube!

[6] It is much easier to maintain a consistent bevel sharpening side to side freehand (parallel to the cutting edge), rather than sharpening from the cutting edge to the start of the bevel. I have noticed this in student work as well as my own.  This does necessitate a flat stone or sharpening surface, however.  Of course, it is possible to sharpen in almost any direction, as long as you hand is comfortable and you are able to maintain a consistent angle.

[7] It is much faster and easier to have a series of small grit progressions, rather than one or two large ones.  This also results in less wear per stone. Always buy the longest stone you can afford and use the entire surface of it — moving the blade 10 inches once is basically the same as moving the blade 2 inches,  5 times. Hogging the center will wear a stone unevenly.

[8] Always use a lubricant.  A glazed system will generate heat and cut very slowly.

[9] Feeling, or looking for the burr lets you know that the two planes have exceeded the point where they meet. This assures you there are no flat (dull) areas on the cutting edge. With very fine grits it may not be possible to feel or see this.

[10] Almost any sharpening system can work, if you know what you are doing. I’ve seen people break every one of these commandments and still get a great edge.



Hock, Ron. The Perfect Edge: The Ultimate Guide to Sharpening for Woodworkers. Cincinnati: Popular Woodworking Books, 2009.

Ron Hock’s brief sharpening notes

Lee, Leonard. The Complete Guide to Sharpening. Newtown, CT: The Taunton Press, 1995.

Maurice Fraser’s sharpening notes

Sugai, Chiharu. The Chef’s Edge: Traditional Hand-Sharpening Techniques for Japanese and Western-Style Yanagi Knives. (DVD) KORIN Japanese Trading Co., 2003.

Hospital Grinder


One of the many great things about New York City is the plethora of sidewalk vendors.  Recently, amidst a pile of used clothes, I saw this beautifully polished aluminum machine.  I sent some photos to mixed media artist and pathologist  Dr. Charlie Weissman and he speculates:

Never seen this exact machine, but probably dates from the era before most equipment was disposable, now it is easier to dispose of much equipment rather than try to get it sterilized completely and reconditined and sharpened. Looks too large for blood-drawing needles, but there are a variety of round penetrating devices– trocars  and such– for drawing off thicker fluids from various body sites, which could have been reused.  Bone-marrow biopsy needles could have this caliber.  Large biopsy needles for liver and prostate used to be reused. Modern  breast biopsy and brain biopsy needles can be large but they are not reused.  Looks a little large for spinal needle. Interesting.

The arm is adjustable for length, and simple slides back and forth to switch from one wheel to the next, which are three different grits.   It operates at a fairly slow speed, and since the motor is not shielded from the wheels, I’m guessing it was used dry. The clamping mechanism near the wheels forms a 90 degree angle, so it was likely used for round objects.  It even came in a velvet lined, fake leather grain covered wood box with a handle. Stylistically, it looks circa. 1930’s to me.  All for $10.00!