Nov 2002 test results
	Finest abrasives.
	Microbevels front and back.
	Use a jig.
	Copyright (c) 2002-09, Brent Beach

Test Changes

In November 2002 I picked 15 typical blades and tested them all again.

The idea behind testing a large number of irons at the same time was to try to reduce the variation between tests. Although I follow the same basic sequence of steps in all tests, by doing 15 blades in parallel (perform one step on all 15 blades before going on to the next step), I felt more consistency was possible.

I also developed a new jig to hold the blade for viewing with the microscope. In all former image captures the blade was horizontal. This is not very good for images of the bevel since it means the surface being viewed is actually sloped down at the bevel angle - typically around 30 degrees. With the very limited depth of field at 200 times magnification, this usually meant that only a very narrow section of the bevel was clearly in focus.

The new jig holds the blade at about 30 degrees to the horizontal. This means that the bevel is almost horizontal. Usually now the entire image is in focus.

There is no gain without a little pain though, and the pain in this case is that it is now harder to light the surface with an external light. The light in the microscope is not bright enough to provide clear pictures, so external illumination is required. When the bevel was sloped at 30 degrees it was easy to reflect an external light off the bevel into the microscope camera. Now that the bevel is horizontal, this is much more difficult.

Sharpening

In all cases I angled the jig only when doing the third bevel. The scratches for the other bevels are perpendicular to the edge.

I put back bevels on all irons.

The Test

The width of the wear bevel, expressed in pixels, was estimated from the image. By taking a picture of a ruler, I was able to determine that an object 1/32 inches wide was 440 pixels wide in the image. That is, one pixel corresponds to about 0.00007".

A plane works pretty well until the lower wear bevel gets over 8 pixels wide. At that point, the downward force required to take a shaving starts to making planing difficult.

The Results

Maker	Steel Type	Wear bevel width	Worn blade
Academy Saw Works	HSS	4
ECE	Alloy	7
Ekilstuna	High Carbon	7
Hock	High Carbon	7
Hock	High Carbon	7
Holtey	HSS+	5
Lee Valley	A2	6
Lie-Nielsen	W1	6
Lie-Nielsen	A2	6
Marples BB	High Carbon	8
Parplus	High Carbon	7
Parplus	High Carbon	8
Smooth Cut	High Carbon?	7
Stanley V logo	High Carbon	7
Stanley V logo	High Carbon	6

Stanley Laminated Blades

Stanley made a number of claims in favour of their laminated blades, some of which may be true. I include a few observations here.

1. Forming the primary bevel on a bench stone is faster for laminated blades. I have done both the blades shown below at the same angle using a Silicon Carbide bench stone and the laminated blade took about half the time.
2. The laminated blade was slightly more durable than the non-laminated blade.
3. Stanley claimed that they could use higher carbon steel in the laminated blade than was possible in a blade from sheet steel of uniform composition. It is not clear why this was the case. Was it a cost issue (highest carbon steel at a competitive price), from a production point of view (problems with making a completely high carbon steel blade), or user (too hard to grind) point of view.
4. At least later on in the laminated blade period (the notched rectangle logo blades after 1925) the lamination was high carbon steel "alloyed with tungsten, manganese and other elements in ideal proportions." Even later notched logo blades were still alloyed, but no longer laminated.

In evaluating these claims about usability, we have to put ourselves in the times the claims were made. Until I tried to grind the primary bevels with a bench stone, it did not occur to me that one was easier to grind than the other. On powered grinders, the difference would not be noticed. Perhaps the hype is true.

This picture shows two blades, both with the V logo, but with slightly different looks to them. Stanley used this logo from about 1914 to 1918. At least some earlier WW logo irons, made from 1909 to 1914, are laminated. Stanley stopped making laminated blades some time in the 1930s. The blade on the left, with T2 scratched on the left side, is a laminated blade, while the blade on the left is not laminated. Notice that the laminated blade has a more deeply stamped logo.
This is a 600 dpi scan of the primary bevel of a non-laminated blade. The blade shows a single primary bevel, that is uniformly scratched.
This is a 600 dpi scan of the primary bevel of a laminated blade. This bevel clearly shows two bands. Starting from the edge, the first band, about 40% of the width of the bevel, is the high-carbon steel. The second, wider band, about 60% of the width of the bevel, is the low carbon steel.

LINKS

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