Tool History Archives

January 30, 2006

A Brief Summary of the Different Types of Japanese Waterstones:

Origins of Sharpening Stones:

The Japanese have traditionally used sharpening stones which are lubricated with water to sharpen their metal tools. As they have been doing this for many hundreds of years, it is obvious that the first stones were those which were found occuring naturally. The geology of Japan provided a type of stone which consists of fine silicate particles in a clay matrix.

This is somewhat softer than Novaculite which is the mineral which forms what is commonly called an "Arkansas" or "Washita" stone. Novaculite is from the Devonian period and Mississippian periods (roughly about the time that cockroaches first appeared on earth 410-325 million years ago) It is a sedimentary rock composed mostly of microcrystalline quartz and is basically a recrystallized variety of chert. It is also the primary material in "Charnley Forest" and "Turkey" oilstones.

Japanese stones are also sedimentary but I've been unable to find out much about their geological history. Some say that they are composed of volcanic materials but I can't confirm that. The most famous are typically mined in the Narutaki District just North of Kyoto.

Advantages of Japanese Water Stones:

These softer Japanese stones have a few advantages over harder stones. First, because they are softer they do not get glazed or loaded with the material they are sharpening. New particles are constantly exposed as you work with the and thus they continue to cut consistantly. Second, they can be lubricated effectively with water (rather than oil) so nothing but a bucket of water is required. Finally, because they are soft, the worn material and the water form a slurry which in conjunction with the stone, sharpens and polishes the blade. The disadvantage should be obvious... they wear out faster.

Grades of Japanese Water Stones:

Historically there are three broad grades of sharpening stones. The Ara-to, or "rough stone", The Naka-to or "middle/medium stone" and the shiage-to or "finishing stone". There is a fourth type of stone which is used, but not directly. That is the nagura which is used to form a cutting slurry on the shiage-to or finishing stone which is often too hard to create the necessary slurry. Converting these names to absolute grit size is difficult as the classes are broad and natural stones have no inherent "grit number". But if I were pressed, the Ara-to is probably 500-1000 grit. The Naka-to is probably 3000-5000 grit and the Shiage-to is likely 7000-10000 grit.

The Rise of the Artificial or Ceramic Sharpening Stone:

Although there is a certain amount of romance associated with using stone which is found naturally, there are some problems with this. First, over hundreds of years, the best mines have given up much of their best stones. This scarcity causes high prices for a good quality consistant stone. Lesser quality stones have problems of consistancy and may have occasional larger pieces of grit or soft spots. With this in mind, and with modern technologies, artifical stones came to the market. There have been a variety of formulations over the years and the quality of artificial stones continues to increase.

For most users artificial stones offer many improvements over the natural stones of the past. In fact, I prefer them to the natural stone (of unknown provenance) that I have. In my opinion, the best of the artificial stones so far are the Shapton stones. Because of the way they are made they are less porous than the typical artificial waterstone and do not require the soaking that other artificial or natural stones require. They cut quickly and and seem to wear longer than the other stones on the market. It is clear that the era of the natural stone is over for all but the most traditional craftsman or specialists. The high cost and difficulty of obtaining quality natural stones make them impractical for most.

Note that I am ignoring the whole art of sharpening and polishing swords. As an art by itself, there are a greater number of steps and more specialized processes.

An explanation of the basic polishing process is here: Process

You can find materials and stones here: Namikawa Heibei

And for some words from a master sword polisher: Kenji Mishina

Link to Shapton's website: Shapton USA

April 5, 2006

K-rail concrete barrier

Yes, it is not strictly a tool, but it has become ubiquitous. "K-rail" - California's version of the New Jersey Type 50 concrete barrier is inescapable if you are driving in this state.
There are a few reasons for this - it is fairly cheap over its lifespan, almost unbreakable, it doesn't kill people when they hit it at an angle (it lifts the car off the ground and slows it so it doesn't spin around or flip) and it is pretty effective at keeping the people behind the barrier safe. The basic shape is the result of observations made by New Jersey police 40-50 years ago. The past 20 years have seen an explosion in the use of it however.

There are improvements to the shape of the K-rail profile, in particular one called the "F-shape" in which the bottom section is not quite as steep. Crash tests show it is a bit better, but with hundreds or perhaps thousands of miles of this stuff already made and slipforms all set with the K-rail profile I don't see change coming anytime soon. Sometimes being good enough is good enough.

The yellow cans in the back are filled with sand in the upper portion. The bottom is typically empty. Since the K-rail isn't going to move, you need something on any exposed end to absorb any shock.

As an aside, the building in the background behind all these barriers is the Silicon Valley office of Microsoft.

May 14, 2006

Japanese Ryoba Handsaw


If you haven't tried a Japanese two-sided (what is called a ryoba) saw, you should. Particularly if you are working with softwoods. There are a number of advantages over Western pattern saws:

  • The ryoba has a rip saw on one side and a cross-cut saw on the other.
  • The saw cuts on the pull stroke so it is under tension when cutting and won't bend or buckle when it sticks.
  • The blade is thinner which means less wood is cut and thus less effort is required.
  • The long handle helps you line up the cut.

The first item on the list bears a bit of explaining. Saws are designed differently according to how they will cut the wood. In general, saws to cut across the grain (cross-cut) have blades which cut the wood. The edge of the tooth is shaped more like a knife and cuts the fibers of the wood. A rip saw which cuts with the grain of the wood has teeth which are shaped more like a chisel and take bites out of the wood. You can see the difference in these two illustrations:.

e-nokoha1.jpg e-nokoha3.jpg

Of course, Western pattern saws have advantages too. I think they show up more when cutting hardwoods though. I mostly am cutting softwoods and find that the ryoba is more useful to me than the classical Western saw. But here are the advantages of the Western saw:

  • Cuts on the push stroke so you can put some of the weight of your body behind it.
  • Thicker blade means that it is stiffer and may help you get started on a straighter cut.
  • Some find the typical pistol-grip handle wo tbe more comfortable.
  • Deeper tone when playing the saw
  • Sawdust ends up on the other side of the wood from you.

There are probably some more, but for now, there aren't enough to make me switch. It takes a bit of practice and some attention to your stance to use it well, but the same is true of almost any tool.

There are a number of other patterns of Japanese saws as well. Some are rounded so you can start cutting in the middle of a panel, others have reinforced backs like a Western backsaw. If you want to learn more and see some pictures of the other types of saws, this site offers a bit of history:

May 23, 2006

Stanley vs. Steve - Battle of the Planes


This #4 Bailey plane is a refugee from sometime before WWII. I'm not sure exactly when it was made, but it is one of a large number of cast-iron planes which were common before the age of power tools. Of course, since it is cordless it is still usable. Cast iron planes like this had a few advantages over the wooden bodied planes they displaced.:

  • Levers and screws for adjusting the plane blade. The lever which is visible at the top of the plane skews the blade from side to side to make sure it is going to cut an even depth across the width of the blade. The brass adjusting knob sets the distance that the blade extends from the sole. This controls the depth of the cut.
  • Cast-iron bodies don't warp with changes in humidity (they rust)
  • Cast iron soles wear longer and therefore the mouth of the plane - essential for taking a fine cut - stays consistant over time.
  • They are easily mass-produced and the final adjustment can be made by the user.

This was probably one of the first planes I owned. I'm sure I picked it up at a garage sale or flea market, brought it home, sharpened it up and used it for things like planing door bottoms or putting a chamfer on posts. It is great for rough work. While it works well, it is not perfect. And in fact, getting better meant taking a step backwards.


This is what I mean by going backwards. No more iron. No more screw/lever adjustments. Just a block of wood, a wedge, and a couple of set screws. This is a plane made by Steve Knight sometime early this century. Steve is one of a handful of retro-plane makers who take the designs of the past and re-interpret them in new materials or in differing ways. In this case, some of the woods are not traditional. The sole is made of Ipe - a hard tropical wood and the thing is laminated together using modern glues. The dark-brown l piece of wood is held in by a couple of screws and is used to control the width of the mouth of the plane as it wears. But really the biggest change between this and the other plane is the thickness of the blade.

As you can see from the two photos below, the Stanley blade is thin. It is about an eighth of an inch thick and thus is somewhat flexible. The chip-breaker (the curved piece above the blade) adds some minimal support to it, but it does not compare to the very thick blade on the Steve Knight smoother.


With this thicker blade, and a mouth that can be closed down to a very fine width, the Steve Knight plane can take much finer cuts than the Stanley ever did for me. It has a couple of other advantages as well:

  • Wooden body is warm and easy on the hands.
  • The shape allows shifting your grip depending on the direction you are planing
  • Slides well over the workpiece and is incapable of leaving a rust mark
  • Retro / Handmade feel
  • Thicker blade is easier to get a nice flat edge on.
  • Can flatten the sole quickly by running it over some sandpaper

There are some disadvantages to it. Adjustment is done by tapping the blade with a mallet. It can take a while to get the hang of that. Potentialy the wood could warp and twist, but so far it seems very stable in the moderate climate I live in.

So for fine work the victor of the battle is actually the simpler of the two. Of course for rougher work I still pull out the cast iron plane. Nothing wrong with having more than one tool for the job.

Some plane links:

  • For history and Identification of Stanley planes nothing beats Patrick Leach's "Blood and Gore" site
  • For more about Steve Knight's planes go to the source: Knight Toolworks
  • HNT Gordon offers some lovely wood and brass shoulder planes at their store.
  • St. James Bay offers a number of planes based on old designs.

There are a number of other boutique plane makers out there like those of Thomas Lie-Nielsen who updates classical designs or the new Veritas line of planes from Lee Valley which seek to add new features while updating traditional designs.

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