Thread: Low budget low RPM grinding wheel project

So I've been thinking about making a low-RPM grinding wheel. The ones they sell at woodworking supply places are 1700 RPM, which is slower than 3500, but still much too fast.

I found this single-phase 3500 RPM motor at the used tool place for $10, with the grinding wheel for $0.50. Shaft collars are from the HW store, $5 for the pair, pillow blocks from the Bay, $15 for the pair.

I can get v-belt pulleys and 5/8" bar from McMaster-Carr. The smallest & biggest pulleys they have will gear the motor down to around 600 RPM. I'll have to get a cogged V-belt because the small pulley is only 1.75" dia.

Do I need an idler pulley? The mount holes for the motor are slotted, I was thinking I could use that to take the slack out of the belt. Are belts fairly stable once the initial stretch is out of them?

Any advice is appreciated.

I would not use an idler pulley I would use one of those link belts, or just space the motor and pillow blocks where you want them. I think that Enco might be less expensive than McMaster Carr for the rod.

I had a set up like this for awhile I ground a few razors on it. It worked but was slow. I would slap it together as simply as I could then make any refinements form there.

Here is the link to how I set mine up http://www.straightrazorplace.com/fo...w-grinder.html

Charlie

Nice contraption. Do you think 600 RPM is a good speed?

600 sounds good to me, try it and see what you think.

Charlie

Update: a box just arrived from McMaster Carr containing pulleys, a 9" drive shaft, belt, and reducer bushings for the grinding wheel. Gonna use Charlie's trick of mounting the motor on a hinged base to tension the belt. I sized the belt to put the grinding wheel 2 feet away from the motor, to keep metal particles away from the motor. This should be slow enough that I can use it dry and keep a bucket of ice water on hand to cool the work piece, but we'll see how it goes.

The idea of using a jackshaft to reduce rpms has been around a long time. Eventually you might find one of the four-size-in-one pulleys and be able to change speeds on the fly...

Getting the wheel away from the motor also gives you a lot more room to work around the face of the wheel. This looks to be a good project.

OK, here's where I'm at with it so far. I stole Charlie's trick for tensioning the belt, but the whole thing seems a little rickety, not sure that I'm happy with it. Anyway, tomorrow I plan to add a switch and a plug, plus I need a couple 5/8" washers to mount the grinding wheel. I plan to mainly use the face for flat-grinding knives. If I ever try to make a razor, I could use the edge to hollow grind, but I don't like hollow ground knives. Hopefully that huge pulley won't be in the way.