Tweaking a Bench Grinder

[Jerry Murray]

I have a HF 6" bench grinder that turns at 3400 rpm. I would like to slow this down...how can I do it?

[Dave Cav]

Short answer, you probably can't. Nearly all AC motors are fixed speed, so you're stuck with it. A router speed control won't work because they're designed to work with a brush type ac/dc motor, which your grinder probably isn't.

[Jerry Murray]

Thanks, I'll take this one back and spend the extra to get one with a variable speed.

[glenn bradley]

I'll back Dave up to some degree; your grinder motor probably cannot be slowed down. Motors with brushes like your router can use a variable speed control. If they would work on grinders, I would use my spare control on my "vibro-matic" grinder (that name is a joke BTW). I saved myself a lot of grief in trying to balance my grinder wheels by removing them and finding the motor vibrated pretty well even without them. I'm in the market for a good grinder; I just can't get a good edge on something that moves like a back massager ;-)

[Paul Atkins]

Get an arbor with pillow blocks, put a small pulley on the grinder motor and run a belt to the larger pulley on the arbor - any speed you want. How's that for tweeking?

[Jerry Murray]

Thanks...I took the HF unit back and picked up a Delta Variable speed job from Lowes.

This should do the job as intended.