Hand Tools Archive

Subject:
More experiences making a hollow on a blade *PIC*

Winston
I've tried a few other things to make a hollow on the backs of plane blades.

First, I should mention that with the Stanley blade I tested before, I was able to completely remove the hollow by working the back of the blade on a 1000 grit Shapton stone for about 2 minutes. So if you do this to a blade, the hollow is shallow enough that you can undo it if you want. In normal sharpening, it should be easy to have the flat area move back with the edge. I'll certainly never have to tap out the blade, like a Japanese plane blade.

First, I got a small 3" cotton buffing wheel, as well as a 3" hard felt buffing wheel, mounted them on a full-speed (3450 rpm) 6" bench grinder, and used the wheels with the same buffing compound. I had hoped that the larger wheel (compared to the 1" dremel wheel) would make it easier to create a smoother-shaped hollow on the back. (I figured that too large a wheel, like 6", would make it difficult to work close to the edge and sides of the blade without actually touching them with the wheel.)

The result is that both wheels were completely ineffective, and didn't remove material fast enough to do anything. I suspect that the much smaller contact area of the small Dremel wheel allows much more pressure (force per area), which removes material much faster. I think the surface speed is also much faster with the Dremel, because the rpms are so much higher. With the Dremel, it threw off some small sparks; with the felt and cotton wheels on the bench buffer, there were no sparks. And the material removal rate was way to low -- after using the buffer on the blade for almost 10 minutes, I took the blade to the 6000 grit stone, and after a few seconds on the stone, almost the whole back, except for a small area in the middle, was showing scratches from the stone. So the hollow was just too shallow.

I've gone back to the 1" Dremel wheel and used it on a couple of blades. One of these is from a WoodRiver bench plane, which is made from T10 steel. My understanding is that this is a pretty simple carbon steel. It took a bit more time to put a hollow in this blade, compared to the cheap Stanley block plane blade I used previously. Maybe 5-10 minutes. The result looks slightly better than my previous attempts. (This is hard to photograph well -- it actually looks a bit better in real life.)

Again, this dramatically speeds up honing the back, especially when combined with David's advice to focus pressure right at the edge. The cutting edge and sides get polished very quickly on the stone; the middle doesn't.

I also tried this on a Chinese HSS blade. I think it's the same kind that David has talked about -- it can be used in a Stanley-style plane, and is painted green. This technique was completely useless on that blade. I couldn't make a dent in the steel with the Dremel and 120-grit buffing compound. It just polished the metal, but it didn't remove enough material to actually be useful.

I like the practical result of doing this, but I still wish I had a better method, one that produces a nicer-looking hollow and is effective even on more difficult steels. I think it would require a wheel that has some give like the felt wheel (a grinder wheel is way too hard), but also is more abrasive than this buffing compound on a felt wheel.

© 1998 - 2017 by Ellis Walentine. All rights reserved.
No parts of this web site may be reproduced in any form or by
any means without the written permission of the publisher.

WOODCENTRAL, P.O. BOX 493, SPRINGTOWN, PA 18081