On 1 May 2005 14:55:09 -0700, "Never Enough Money"
wrote:

I need to get the initial edge on new chisels (the "hollow grind").

You certainly don't need a hollow grind on anything except razors, and
they're different again.

That said, I'd be lost without a powered wheel for initial shaping on
boot-sale pre-war chisels.

Everything I've read says to use a slow speed grinder with aluminum
oxide wheels to prevent overheating of the steel (which ruins the
chisel).

Aluminium oxide (white) and a "half speed" grinder are a good start.

The woodturners are probably the experts though, as they do a lot of
sharpening with this type of equipment (rather than finishing with a
bench stone). They're now using pink stones rather than white, as they
run cooler.

It's also worth finding a grinder (or at least spindle) that can take a
40mm wide stone, not the 20mm or 25mm that are more common at the cheap
end. You can always upgrade the stone later, so long as the spindle is
long enough.

I've been told that the grinder should not exceed about 1200 RPM.

Nice idea, but impractical. Induction motors don't run at that speed, so
you'd need reduction belt drives. A 4 pole induction motor will run at
1750 rpm (1425 in the UK) and that's close enough for a cheap direct
drive grinder. 2 pole motors run at around 3000 rpm and so the really
cheap metalworking grinders are too fast for this.


One local woodworker actually keeps a cup of water next to his slow speed
super expensive Baldor grinder.

Not the best idea. You're better cooling with airflow (which the stone
provides) or cooling much more frequently than this. 5 seconds is just
enough to set up hot/cold cycling that's going to avoid drawing the
temper, but may also give rise to microcracking in a hard steel.

I currently have an $70 Delta 1750 RPM grinder. I can get aluminum
oxide wheels for it, too. How risky is it to use it?

Sounds fine.



Read Leonard Lee's book too.


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