Tag Archives: paring leather

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.

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


Weights of Litho Stones


G. Ruse and C. Straker. Printing and its Accessories. London: S. Straker & Son., 1860. Robertson Davies Library, Massey College. University of Toronto.

This is a pretty handy chart if you are considering purchasing a litho stone, or even picking one up to move around.  For example, a 16 x 12 inch stone weights 43 pounds per inch of thickness. This was pasted onto the inner face of the front board of Printing and its Accessories from Massy College.  Another reminder that many printed books contain unique, owner added paratextual information.

Paring on Glass

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Charles Tomas Jacobi The Printers’ Handbook of Trade Recipes, Hints & Suggestions  (London: Chiswick Press, 1891), 265.

Yes, yes, and yes. Note there is no mention of a litho stone. 18th century paring surfaces seem to generally be marble, I suspect the only reason litho stones became popular was that they were a cheap plentiful source of a flat surface in the late 19th. Save the litho stones for the printers or your beautiful bookbinding photography.

“Feeling Small” While Paring Leather

There is a recent New York Times article which describes the difficulties of creating a robot with a sense of touch comparable to a human. One of the links in the article, “Feeling Small: Exploring the Tactile Perception Limits”, contains suprising results. It turns out our fingers are exponentially more sensitive than previous research has indicated. Earlier studies used abrasive paper, while this study used wave-like ridges, which may account for some of the difference in the new findings.

Human fingers, when using “dynamic touch” — sliding across a surface — can distinguish a ridge that is 13 nanometers, which is .013 microns, or about .0000005 of an inch. For comparison, the thickness of a sheet of standard copy paper is a mountainous .004 of an inch thick. The average particle size of green chromium oxide stropping compound is .5 micron, which produces a mirror finish on steel.

My mind is blown. Should I be able to feel the individual fibers on a Japanese tissue paper repair? Will I ever be able to pare leather smoothly enough?

Razor Blade Planes: A Plane Designed for Paring Leather

In part one of this three part series, I presented an overview of some vintage razor blade planes.  In part two, Eric Alstrom gave some tips on using them.  Here, I explore some of the issues I grappled with while attempting to come up with a razor blade plane specifically designed for leather.

I have found there are four basic problems with existing razor blade planes when used to pare leather: the blade is usually at too high of an angle, the poor quality metal they are made out of creates excessive friction and threaded parts can strip out, the blade height is difficult to adjust and standard razor blades, because they are so thin and designed for hair, are not ideal.

Bruce Matthews published some plans and images of a plane he designed for model making, primarily dealing with balsa wood. In order to correct some of the limitations of a flexible double edge blade, he used a single edge blade that has a back stiffener.

Bruce Matthew’s Plans for a single edge razor blade block plane

I adopted these plans for a plane specifically designed for leather.  First, I lowered the blade angle to about 20 degrees. Secondly, I made the body out of a single piece of milled aluminum, rather than friction generating wood.  I also milled the front of the plane a bit more to create space for leather parings and used magnets to hold the razor blade in place before final clamping, to aid in blade adjustment.

The most difficult problem was edge retention of the blades – this problem still needs to be resolved.  Other than carbon steel and stainless steel, there are ceramic, ceramic coated,tungsten carbide, and diamond coated carbide blades.  Ceramic blades were too brittle, and diamond coated carbide blades were too expensive.  So I experimented with two possibilities, ceramic coated blades and carbide blades. The ceramic coated blades reduce the initial cutting performance to an unacceptable degree, but the carbide blades performed reasonably well, although they are not as sharp initially, they have a much longer, more gradual use time, though seeming not as long as the 75 times some suppliers claim. High carbon blades cut great initally, but don’t seem to last as long as one would hope.  Or course, this is part of the expense for the convenience of disposable blades.

Three blades, spanning 100 years, all with nearly identical hole spacing.  On the top, a circa. 1910 Gillette,in the middle a 1990’s Scharf-fix, and on the bottom a 2011 Tungsten Carbide industrial blade.

Most modern double edge razor blades have some sort of  proprietary slit cut through them, but all of the ones I have tried fit into the three hole system pictured above.  Note: The Gillette blade is stamped “NOT TO BE RESHARPENED” and “DESIGNED ONLY FOR ORIGINAL USE IN GILLETTE HOLDER”.  I hope that the Gillette police are not watching, but perhaps the easiest solution for rapidlly dulling blades is to resharpen them. This can be done by hand or with various antique machines. Carbide blades are too hard to be stropped or resharpened by hand.

Stropping a razor blade.  A strong binder clip is a simple way to hold the blade. 

A simple holder is to use a one inch wide binder clip on a horsebutt strop prepped with .5 micron chromium oxide, followed by a final strop on undressed calf. The binder clip is lightweight enough to allow a feel for the flexing of these thin blades, making sure to sharpen them on the bevel, although I tend to take a couple of degrees off the angle to make the edge a bit more robust.  This can be done a number of times before the angle becomes too obtuse. The blades flex quite a bit, so a slow, gentle touch is necessary.

There are various devices for resharpening double edge razor blades.  One common one is the Twinplex Stropper.  There are many versions of this device, though all are similar in that both edges of the blade are sharpened on one side, and then the blade is automatically flipped and the other side sharpened. This is much quicker than hand stropping.




A razor blade plane designed for leather

This is the result of trying out a number of ideas to develop a better razor blade plane for paring leather. I don’t think it works better than a spokeshave, but it is easier to adjust than a Little Giant or Wilkro. It might be useful for specific circumstances, like paring very thinly, or for those who don’t want to bother having to resharpen their blade. The body is 6061-T6 aluminum, the blade cap and screws brass. Two rare earth magnets hold the razor blades in place for adjustments until they are securely clamped.  Either standard double edge razor blades, Scharf-Fix blades, or industrial three hole Tungston Carbide blades fit.

Blade cap with magnets to hold the blade in place for depth adjustment before tightening.

I used magnets to hold the razor blades in place until final clamping, and also used a blade cap more like a normal block plane.  Blades can be changed without an additional tool.  Since everything on the plane is nonferrous, the magnets only stick the blade to the cap and allow it to be adjusted from the tightening knob. This makes tightening easier, but still takes a little practice, much like a spokeshave.

It cuts quite differently than a a spokeshave or a Scharf-fix.  It splits the thickness of the leather more like a paring machine, but allows more immediate depth of cut adjustment by adjusting hand pressure. Like a spokeshave, it it relatively easy to achieve long, gradual bevels. It is also easier to pare larger, flat areas than with a spokeshave.

Below is a video of it in use. I find it easier to use parallel to the edge of the leather. At the beginning I’m taking a fairly aggressive cut, but later taking lighter, quicker ones to even the thickness. I’ll keep tweaking this plane and bring it along to the Guild of Book Workers Standards of Excellence Seminar, October 6-8, 2011 in Boston.


Paring In Action

I finally made a (very) short video showing edge paring using an English style A2 Cryo knife. Hopefully, early next year, in the new tool catalog, there will be videos of all the tools in action.  In the meantime, descriptions and images of tools are in the “TOOL CATALOG”  in the right hand column.

Video seems a promising technology for the preservation of craft based knowledge: it can clearly demonstrate and record hand skill techniques.  It can also be potentially misleading in terms of how easily a tool is used, and “special effects” are available on any computer.  But videos are popular, great for marketing, persuasive and hot right now.

Sit back, eat a piece of popcorn and enjoy the next 39 seconds.