dimmer on grinder

I am building a billiard ball polisher. All it takes is some type of motor that will turn a turntable covered with carpet. Google how to build a billiard ball polisher. I have an old right angle 7" grinder I never use that would work. Can I safely put a dimmer on this to vary the speed and slow it down?
Steve
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Steve B wrote:

no. it most probably has a universal motor and this will burn it up.
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On 5/9/2011 10:04 AM chaniarts spake thus:

Wrong. If it *does* have a "universal" (i.e., shunt-wired AC/DC motor w/brushes), then a dimmer *will* work as a speed control. That's essentially what variable-speed power tools use.
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Wrong. David Nebenzahl is 100% right.
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On 5/9/2011 2:29 PM hr(bob) snipped-for-privacy@att.net spake thus:

Of course I am! Thanks for pointing it out.
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On 5/9/2011 11:42 AM, Steve B wrote:

You really need an AC motor speed control. Here are three sold by W.W. Grainger:
http://preview.tinyurl.com/6dlzhxf
http://preview.tinyurl.com/6kupsdx
http://preview.tinyurl.com/5wr8ott
TDD
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On Mon, 9 May 2011 09:42:33 -0700, "Steve B"

I think you'd be better off buying a $20 orbital polisher from HF. [or a $35 one from Amazon or Walmart]

http://www.youtube.com/watch?v=DNPdZJXbpyc

There is a bit of randomness to its orbit that prevents it just grooving a ball if a speck of crud gets in your polisher. Plus you don't need to mess with the speed. [And what kind of welder are you that you have a grinder you don't *need*.<g> ]
Jim
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Safely, probably yes; vary the speed, no.
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wrote:

I have since found a brand new 1/3 hp electric motor in my shop that will work perfectly with a little reduction.
hmmmmmmm. I wonder what else is out there ....................
Steve
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On 5/9/2011 4:29 PM Steve B spake thus:

Well, whoa, wait a minute there, pal. You mean a regular induction motor, like you'd find on a bench grinder, jig saw, that type of stationary power tool? Sorry, you can't vary its speed with a dimmer. That only works on "universal"-type motors (electric drills, etc.). You know, the kind of motor that has brushes, sparks and all that.
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On Mon, 9 May 2011 16:29:36 -0700, "Steve B"

It WILL slow it down. Some dimmers will take the counter EMF from the brushed motor, some won't - so the "safely" part is a mabee. Won't hurt the grinder, either way
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I would try it with a 2000 w dimmer, I don know if a regular dimmer will work or even last with the startup surge but maybe it will. If it doesnt work you know.
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Why would you need to polish billard balls? You run a pool hall? Fwiw, I use a vibrating bullet casing polisher to polish pinballs and small pinball parts. It was pretty cheap.
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On Tue, 10 May 2011 07:54:24 -0700 (PDT), jamesgangnc

I've never polished my balls, and they work perfectly!
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On Mon, 9 May 2011 09:42:33 -0700, "Steve B"

Get an old record player from a garage sale or online auction for a couple bucks. A grinder will probably be too fast anyhow, even if you can reduce the speed.
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