How to slow down a 6” grinder

I’m sure that we have a good electrical person on site.
I have a 6” standard type bench grinder that runs on 120 v household current. It turns at a ridiculous speed and I’m wanting to use it for some things other than grinding is there a variable reostat or device I could install on the power line to slow it less than 50 rpm? And where can i purchase Thanks in advance for any ideas



Inverter ………

Variable frequency drive

I spoke too soon and sman knows stuff.

I tried it once with a dimmer switch and it would slow down, but with a significant amount of torque loss, so I gave up.

I use a bench grinder for all kinds of things but, I have a specific one I use to sharpen all of my woodturning tools. I recently bought a CBN wheel for it which I heartily recommend for more precise sharpening. My big regret though, not getting a variable speed grinder. Like you, I have times I’d love to be able to slow the RPM’s down a bit.

If you find a workable solution, be sure and share. It might be something I’d look into.


I’m not sure it would be worth it to try a reostat. There’s tons of inline switches on Amazon with adjustable output but it really depends on the internal design of the grinder. The motor may require a boost to get it going. Most have a capacitor to do this. Using the adjustable dial would be a PITA to keep it running.

Instead of “rigging” one it may be easier and cheaper in the long run to buy what you need. Not overly expensive…

DELTA 6-in Variable Speed Bench Grinder with Light in the Bench Grinders department at

WEN 6 in. 2.5 Amp Variable Speed Bench Grinder with Flexible Work Light BG625V (

Whoops sorry, overlooked the 50rpm part… That’s sloooooow…

Look at jewelry or hobby grinders. Jewelry Gem Polishing Grinding Machine Bench Lathe Rock Saw Lapidary Polisher Buffer 110V Mini Table Saw DIY Jewelry Grinder Equipment Tool 0-10000r/min with Flexible Shaft : Tools & Home Improvement

I had the same need for my Whaler restoration project. Up until recently I had been using a Dewalt angle grinder with a flat pad on it and it was too aggressive. I ended up getting this tool which is sold as a polisher but its really heavy-duty but is awesome for doing lighter sanding because you can slow it way down. Highly recommend

Thanks Optiker and all the others. That might have to work. I have that Dewalt polisher and I will give it a try .

What I was envisioning was a floor control like a sewing machine speed control, But the Dewalt might work I havent had that tool out in a while. any other suggestions ?

thanks again everyone