Toolmaker Comments, Please

I been asked to do an article that involves, among other things, talking about tool steel.

Being predjudiced as all get-out on the subject...but with ignorance to match...here's what I've written in an attempt to be objective and I'd like y'all to tear it apart:

Quote:

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What you need to know about steel.



High Carbon Steel

After the Henry Bessemer process of making steel was developed and refined during the middle 1800’s to reliably produce large quantities of high-carbon tool steel inexpensively, such steel became the mainstay of edge tool production that continues today. “Warranted Cast Steel”, “Sheffield Steel”, modern 0-1 Tool Steel, “Swedish Steel”, and others. (It was the Swedish iron ore, not necessarily their steel that was better, as it lacked the phosphorous that makes steel brittle.) Many of the chisels made during Bessemer’s lifetime still serve admirably today, as properly forged carbon steel takes an excellent edge while is very easy to resharpen using traditional composite, water or oilstones.

Chrome Vanadium Steel

A modern, shiny tool steel commonly seen in lower grades of chisels. The chromium and vanadium add hardness, toughness and rust resistance, and if properly made, can take a good cutting edge. They are generally more difficult to sharpen than carbon steel, and in lower tool grades can be impossible to obtain an “excellent” cutting edge.

High Speed Steel

M-2 and other formulations. Chromium, tungsten, molybdenum and vanadium are added to resist softening when the steel is overheated during use or sharpening on a high-speed grinder. Used primarily in drill bits and lathe tools, this steel is hard, tough, easy and fast to grind, holds its cutting edge considerably longer than carbon steel, but is very difficult to hand hone and doesn’t take as fine an edge.

A-2 Steel

The modern compromise. High carbon steel with chromium and molybdenum added in smaller amounts than some other modern steels, but sufficient to add some toughness, hardness and longer edge life at minimum expense to the quality of the cutting edge and ease of sharpening. I find these blades only slightly more difficult to hand hone on traditional oil stones than carbon steel, and it is doable without resorting to the modern diamond pastes often recommended. I also find A-2 blades take a very good edge and hold it as long or slightly longer than my best prewar carbon tools.

Rockwell Hardness

More compromises. The Rockwell index is simply a hardness test of the final, tempered steel. Chisels available today can range from RC 56 (relatively soft) to RC 64 (relatively hard). Softer steel is easier to sharpen but doesn’t hold its edge as long as harder steel, which takes longer to sharpen but holds its edge longer. Chisels in the RC 60 range and above can also be brittle, if not during use then when you accidentally knock one on a concrete floor and find you have a badly chipped edge that must be severely reground. As a practical matter working at or close to a bench, I find chisels so fast and easy to touch up on the stones, that harder isn’t better for me - my preference is the sharpest cutting edge I can hone, but hone easily. In my plane irons however, it is real convenient to not have to dismantle, hone, reassemble and adjust any more often than I absolutely have to, and depending on the plane, that preference may be secondary to my best cutting edge.



Forging – does it make a difference?

I think so. Every time a coke-fired, red-hot billet of carbon tool steel is hit with the trip hammer, it is “refined” in blacksmith parlance, meaning that more carbon from the coke and in the steel is worked into a smaller area, and it’s the carbon in steel that provides the excellent cutting edge. Modern tools are generally hit 4 times or so, whereas tools made by older factory methods before WWII were hit as many as 30 times, and hand-forged tools many more times than that.

As a practical matter in edge tools, the differences are often subtle and subjective, but are certainly there. Almost all my older professional friends in the woodworking trades much prefer the best prewar makes of chisels to new factory chisels, however expensive. Hand forged, best-quality steel is the mainstay of legions of knowledgeable Japanese tool woodworkers, and toolmaker Barr Quarton wouldn’t still be in business after over 20 years of hand-forging edge tools if he didn’t have a superior product.

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Bob,

Real informative! I will keep this post handy....I'm printing it! Thanks.

I can't quibble or argue about anything you wrote, but whether you covered things deeply enough or hit it just right would depend on what the article is about. If you're writing for a magazine or ezine I know you have length limitations. If it's for your sons, you might want to expand things quite a bit. No sense in forcing them to reinvent the wheel some time down the road.

Thanks, all.

It's for a mag oriented toward newbie woodworking tool buyers.

I'm trying to get some comments and quotes from known pros in the field, but if that doesn't work out I want to avoid some commercial tool maker coming back and proving me wrong...not on 01 or A2 where I'm comfortable....but on the Chrome-Vanadium I'm poormouthing, which I can't find as a oil or air hardening tool steel, just CV-6140 for wrenches...and more on forging, which is very subjective.

Bob,

From the Hock Tools Website:

"Tool Steel" refers to a class of steels that are metallurgically very "clean" and fall within strict limits for alloy proportions. Vanadium, tungsten, and molybdenum are often added to tool steels to make the steel resist annealing (softening) when used in "high-speed" (high heat) applications. Chromium is added in very large quantities for corrosion resistance ("stainless"). High-speed steels are essential in metal-working tools (drills, milling cutters, etc.) and "stainless" steels can be cost effective by resisting rust during the manufacture, shipping, and storage of the tool itself. Correctly heat-treated, tools made from high-speed, stainless, and "chrome-vanadium" steels may hold an edge well in woodworking applications, but, due to the large, hard carbide particles that form during hardening, they are difficult to sharpen and cannot be honed as sharply as a blade of plain high-carbon steel. Our choice of High-Carbon Tool-Steel (.95% Carbon) offers the finest, sharpest edge possible. Its chromium and vanadium additions amount to only 1/2% each allowing quick, clean honing with traditional techniques. High-carbon steel holds and takes an edge better than anything else. We guarantee it.



Dean

What you need to know about chisel steel.

Here are the steels commonly found in today’s chisels.

High Carbon Steel

After the processes were developed and refined during the middle 1800’s to reliably produce large quantities of high carbon tool steel inexpensively, such steel became the mainstay of edge tool production that continues today. “Warranted Cast Steel”, “Sheffield Steel”, modern 01 and other Tool Steels, “Swedish Steel”, “Crucible Steel”, and others. Many of the chisels made during the late 1800’s still serve admirably today, as properly forged carbon steel takes an excellent edge while is very easy to resharpen using traditional composite, water or oilstones.

Chrome Vanadium Steel

A modern, shiny tool steel used for mechanic’s tools and commonly seen in lower grades of chisels. The chromium and vanadium add hardness, toughness and rust resistance, and if properly made, can take a good cutting edge. I’m not sure if it’s the steel or the manufacturing process, but they are generally more difficult to sharpen than carbon steel, and in lower tool grades can be impossible to obtain an “excellent” cutting edge.

High Speed Steel

M2 and other formulations. Chromium, tungsten, molybdenum and vanadium are added to resist softening when the steel is overheated during use or sharpening on a high-speed grinder. Used primarily in drill bits and lathe tools, this steel is hard, tough, easy and fast to grind, holds its cutting edge longer than carbon steel, but is very difficult to hand hone and doesn’t take as fine an edge.

A2 Steel

The modern compromise. High carbon steel with chromium and molybdenum added in smaller amounts than some other modern steels, but sufficient to add some toughness, hardness and longer edge life at minimum expense to the quality of the cutting edge and ease of sharpening. I find these blades only slightly more difficult to hand hone on traditional oil stones than carbon steel, and it is doable without resorting to the modern diamond pastes often recommended. I also find A2 blades take a very good edge and hold it as long or slightly longer than my best prewar carbon tools.

Rockwell Hardness

More compromises. The Rockwell index is simply a hardness test of the final, tempered blade. Chisels available today can range from RC 56 (relatively soft) to RC 64 (relatively hard). Softer steel is easier to sharpen but doesn’t hold its edge as long as harder steel, which takes longer to sharpen but holds its edge longer. Chisels above the RC 62 range can also be brittle, if not during use then when you accidentally knock one on a concrete floor and find you have a badly chipped edge that must be severely reground, shortening the life of that tool. As a practical matter working at or close to a bench, I find chisels so fast and easy to touch up on the stones, that harder isn’t better for me - my preference is the sharpest cutting edge I can hone, but hone easily. In my plane irons however, it is real convenient to not have to dismantle, hone, reassemble and adjust any more often than I absolutely have to, and depending on the plane, that preference may be secondary to my very best cutting edge.



Forging – does it make a difference?

I think so, but it can be controversial. One view is that the more the hammer is used in shaping the blade as opposed to grinding, the smaller the crystalline structure and the better aligned it is with the cutting edge, with other benefits in carbon and grain size as well. Older tools and hand-forged tools are better because they have been shaped more by forging than modern tools. The counterargument is that modern steels benefit most from proper heat treatment, and that poor results come from manufacturer shortcuts taken to cut costs, not lack of forging. The middle ground is that forging is more expensive, and a manufacturer going to that expense is more likely to get the rest of it right.

As a practical matter in chisels, the differences are often subtle and subjective, but are certainly there. Almost all my older professional friends in the woodworking trades much prefer the best prewar makes of chisels to new factory chisels, however expensive. Hand forged, best-quality steel is the mainstay of legions of knowledgeable Japanese tool woodworkers, and toolmaker Barr Quarton wouldn’t still be in business after over 20 years of hand-forging edge tools if he didn’t have a superior product

Bob,

I like everything you wrote but the forge process may be understated a bit. I think it helps tremendously, that's why you can take one of those thin walled 12 point box wrenches from Sears and hang on it without fear of it breaking. In my working days I used to have a customer that made forged aluminum parts for the aircraft industry. Some of the parts were unbelievably thin, but you could actually stand on some of them without colapsing them. It shapes, compresses and refines the grain structure of the metal.

Gene