Whetstone Grinder Speed

Kevin G

I have a nice whetstone mounted on a stand that was originally driven with an electric motor. I'd like to set it up with an engine to run at tractor shows. It's about 27" in dia. with a 3 1/2" face. Any idea of RPM or SFM I should be running it at besides slow. I have a speed in mind but would like to hear from someone with past experience. TIA.

Joel Sanderson

New member
I don't remember the RPM exactly, but I had one about that size that I ran just fast enough not to throw the water off when it spun. Maybe 60 rpm? 80? Can't remember.

I wonder if that's still stuck up in my dad's barn. If it is, I might be able to figure the speed. Might be long gone though--dunno.

(Not much help, I know.)

Andy Williams

New member
i have one that has been rigged up to a wringer washer transmission from the wringer shaft. i think it runs around 60. i can check to see.


Hadn't ever really thought about it. Always ran mine at whatever speed my hit & miss engine wanted to turn it at. Was never really a crazy speed, less than half what the engine ran. But that still put it into 150-200 rpm, the water would fling off and get everywhere. Yet I never once burned an edge on it, I just had to keep a drip can pouring more water on so it would stay wet.

Anyone found some notes from the time period talking about the subject? Maybe an older edition of The Machinists Handbook would know what the correct SFM for an old millstone should be.