Drive belt suddenly won't stay on

[Roger Feeley]

I have one of those old Craftsman tilting head bandsaws. It's fine as long as you don't tilt the head. This thing is probably 20 years old and never failed me until yesterday. I don't use it much anymore (also have a 17" Rikon) but I fired it up to do a simple thing and the drive belt came off. I put it back on and it came right off again. Tried a third time, thinking maybe I didn't get it centered on the pulley. Came right off.

This is not an old school v-belt. It's one of those ribbed ones. It's certainly isn't as supple as it once was but it seems pretty ok.

What makes belts come off?

[Steve Baumgartner]

Usually this means the pulleys are not aligned with each other. The flat ribbed belts are more prone to coming off because they don't have to climb as far to get out of the the grooves as a traditional v-belt.

[Duane Meadows]

If the pulleys are aligned... replace the belt!

[Erik Loza]

Agreed on replacing the belt. It's probably just old, brittle, and taken a set by now. Wants to jump off every time the "bump" comes around the pulley.

Erik Loza
Minimax USA

[Roger Feeley]

I took the belt off and it seemed ok to me. So I took it over to my local Woodcraft and they thought it looked pretty ok for a 20 year old belt.

So I craned my neck under the saw and found that the pulleys were inded out of aligngment by about a half inch. Considering the small belt, that was a lot. It was the better part of an afternoon getting the pulley back into position.

The set screw was not loose at all. I can only assume that that the pulley had been moving a tiny bit for a very long time. How it went from a condition where belt never came off to the belt refusing to stay on is beyond me.

Thanks to all.