Wednesday, 14 November 2007

hollow grinding Nirvana


That may sound a little extreme - but it is accurate.

While I was in Calgary I had the good fortune to stay with a friend. During one of our many tool fetish moments, I noticed a pale blue wheel in his grinder. So I asked about it. He said it was the best grinding wheel he has ever used - it does not produce any heat. That was a pretty tall order - so I asked if I could give it a try. I have a 1725RPM Baldor grinder with 2 Norton white wheels on it - both 60 grit. They are fantastic wheels, but they can produce heat and even burn steel if you are not careful.

This wheel is completely different. The first thing I tried was a huge high carbon steel iron from a jointing plane. I gave it a pretty light touch and was amazed at how much metal it took off. I did another pass and pressed a little harder - expecting to feel a little warmth in the iron. I felt nothing and started worrying that my caloused fingers were loosing sensation. The blade wasn't even warm! I was going to take another heavy pass, but realized that I had already completely re-ground the iron. Holy smokes this thing was fast!

So I grabbed another iron, and had similar results - fast cutting and no heat to speak of. Then I realized I was using some pretty stout plane irons - I wonder what would happen on a small chisel? So I tried a little 3/4" "blue chip" that was in pretty rough shape. I started again with a light touch. Fast cutting - no heat. I pressed harder... even faster cutting - still no heat. At this point I was totally sold - this was fantastic! So we finished up the chisel and a few other tools that needed some work. There was not a single instance where I felt any warmth in any of the tools we were working on.

I ordered one of these wheels (Norton 3X, 46 grit) from Joel at Tools for Working wood in NY.

2 Comments:

Blogger rookster said...

Thanks for posting this. I've been fiddling with the idea of getting one of those low RPM grinders for the shop, but it sounds like investing in one of these wheels will solve the problem of heat more effectively for much less money!

15 November 2007 at 13:58  
Anonymous jeroen elswijk said...

hello konrad

thanks for sharing your expiriences with this stone, i am thinking of buying one myself
but i am wondering if it is not to coarse?
with how many rpm does your machine work?

3 December 2007 at 07:08  

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