Metallurgical Chisel Photos

So after the discussion that cajunpen initiated on the WS Vs. “other sharpening methods” I decided to take some pictures of my new Irwin chisels using my metallrugical microscope. I also checked the angle that my Veritas Mk2 gauge put on the chisels as well.

In case you aren’t familiar with the Veritas Mk2 gauge (see here for blog entry). It clamps the blade and adjusts both the angle of the main workhead and uses a colored sliding gauge to set the angle. Now I was fairly skeptical of the ability of this blade to hold the advertised angle. So I magnetically clamped my chisel into the optical comparator and, with a preliminary check, it appears to be with 2 minutes of 25 degrees. What does that mean in english? .03 degrees, and also the capability of the optical comparator! Or, .0002 over a 3/8 face. So in a perfect world you have to hone .0002 of material off each time you clamp up the chisel. Not too shabby, I’ve seen far more expensive machine tool equipment be more out of whack than that little dandy, very nice Lee Valley!

But on to my main point, the pictures! I used this chisel for about 20 minutes last night to pare some end grain. There was some pushing, a few whacks with a mallet, but mostly light use. The wood was hard maple, or as I come to like to call it, rock maple.

First a few reference photos to put it into perspective. This is the lettering on the top that says “Made in Sheffield England.” (The HE in Sheffield more particularly)

That is at 40 times magnification.

100 times magnification

400 times magnification

Now the chisel itself, I did the back, the cutting edge and the side.

Chisel and micro bevel at 40X

Chisel and micro bevel at 100X

Micro bevel at 400X

Bottom of the chisel near the cutting edge at 40X

Bottom of chisel at 100X

Bottom of chisel at 400X

Side view of the tip at 40X

Side view of the tip at 100X

The 400X of the side did not turn out, the edges had too much light and I believe I didnt have it perfectly square as I had some ghosting on the image.

So what does it all mean? First off you’ll notice that this looks horrible, like a glacier went through. With the naked eye you can see your reflection on the chisel with no discernible scratches. I start using a 1000 grit water stone and move to a 4000 grit waterstone, no nagure stone though once I get it I’ll try it. Slight rollover is noticable in the photos as well, a knot strike maybe?

As a comparison I’m going to sharpen the chisel tonight using my normal method and then put it back on the microscope so we can get a before and after photo. I’ll also put one my Irwin chisels that I haven’t sharpened yet on there to show the “factory” edge.

I also plan on doing a repeatability study with a chisel in the future. I’ll sharpen it, then remove it from the fixture and resharpen it, see how well it repeats. If how it did this time is any indicator, it is a beautifully accurate piece of equipment.

I’d also like to do an econometric study on using the scary sharp method versus waterstones. So, if you have use the scary sharp method (I don’t) and would like to give me some info, please pipe up!

Enjoy folks, if you folks like stuff like this I’ll try and post more in the future.

C

-- Casey, Engineer, Escanaba, MI