Hand Tools

Subject:
Agitating on recommended grinders...

David Weaver
I don't expect consensus, just tested today at lunch my theory that a coarser dressed wheel will always grind cooler.

But with a twist - instead of comparing normal grinding wheels, I thought I'd reset a couple of used chisels that came from japan, and I'd use a full speed 8" grinder to do it.

A couple of weeks go, I got an A24 wheel (24 grit al-ox vitrified tool room wheel, vs. something more friable) and the matrix is so open on it that it really doesn't glaze or anything like you'd expect for a hard wheel. But from playing, it's also noticeable that it grinds cooler than my broken in 80 grit CBN wheel, especially if it's freshly dressed (and again, it doesn't glaze very quickly, rather I think the open matrix comes apart).

I've used my CBN wheel a lot for restoration and toolmaking and it's getting slow. I was pondering maybe getting another one of the same type (not the cheap type with sharp edges, but the wide rolled edge type, but to my surprise, they have gotten more expensive rather than less).

I figured I'd toss up the experience as a data point to the extreme (24 grit wheels aren't mentioned often in the woodworking community), that on a full speed 8" grinder a simple very coarse wheel grinds cooler than the broken in CBN wheel at the same sharpening rate, or faster at the same heat level.

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