Grinder Shudders When I Press Steel Against Wheel

[The Mighty Ginsu]

My first knife is going better than I thought it would. I stupidly chose a concave edge when I did the sketch, and I thought it would be a horror to grind, but the belt grinder sort of showed me how to do it as I was hacking at it, and it came out very well.

I have a question about grinding. My grinder is an old 1x42 Rockwell with plastic wheels. There were times when it would have been helpful to grind against the upper wheel, using it for support, but when I tried to do that, everything shuddered, leaving random gouges on the steel. It seems like this happens because the wheel is hard. When I ground below the wheel, where the belt was unsupported, I didn't have this issue.

What's the solution? I was thinking a new wheel with some kind of rubber around it might solve the problem, because it would cushion the belt.

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[kuraki]

The outside diameter of your plastic pulley is not concentric with the axle/bearing it rides on. So you can't grind smoothly against it because it's acting like a cam. Rubber cushions compensate for this with the give in the material. It doesn't take much eccentricity to cause problems at high RPMs on a solid wheel, but the cushion can deal with quite a bit before you notice it, depending on the durometer of the material.

A new wheel with rubber would help. If you have a lathe you could true up your hard faced wheel and that might help too. If you come up with a way of putting rubber on a hard wheel and it works, please share it.

 

[Jesse Latham]

Belt bump from the splice.