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HeyBub[_2_] HeyBub[_2_] is offline
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Default pneumatic die grinders-- cheap v quality?

Bernard Arnest wrote:

I do marble carving; started somewhat recently. I've used
chisels so far, but I really need to look at rotary for undercuts and
delicate areas.

I'm considering foredoms, but, air die grinders appeal-- buy a
compressor, which I need for many things anyway , and then plop $20-
$100 for a pneumatic die grinder. They're also higher-rpm, possibly a
benefit though overheating can be as much a worry at high rpm as
chatter may be at low.

For both I worry about dust. Marble... seems harder than mild
steel, when I accidentally forged some mild steel chisels they
mushroomed over instantly; but is rather softer than tool steel. So
the case may be made that some parts in the die grinder are going to
abrade anyway so I should get cheap and recyclable grinders?

This varies categorically. I don't buy dirt-cheap bits for
example, the steel quality and grinding precision is pitiful; a mid-
range I find sufficient value for my needs. I do buy cheap ear
protection, gloves, some lifting equipment-- sometimes the difference
between name brand and brand X is only that, and the products are

So where do die grinders fall? What brands do you like? If I
might burn through bearings; are some better shielded for longer
lifespan --enough so, that $/hour used is lower? Harbor freight?
Random ebay powersellers?
Another issue, beyond bearing slop, is air consumption (also a result
of machining tolerance). My compressor does 8cfm, theoretically, at
90psi; but if name brand vs. brand x is a difference of a few cubic
feet per minute, might be worth the name brand? If only for the noise
(quiet matters) :-)

Pay attention to the RPM. Proper speed varies depending on the target:

Fine grinding 10,000 RPM
Rough grinding and buffing 10,000 - 20,000 RPM
Metal 20,000

They cost less than $20 at HF. If it wears out, toss it.