The Taig's belt drive is, in my opinion, very deficient.

Sure it's got a 1/4hp motor, in theory. However, at the fastest or slowest ratios, the belt will slip long before the motor slows down. No matter how much tension I try to put on the belt when tightening the motor, it's not hard to make the "small" pulley slip just by turning it by hand. So it's not really relevant that it's a 1/4hp motor if the belt will fail at less power. Unless I'm supposed to be using some sort of lever to make the motor tighter before locking down the screws, but no one's told me I'm supposed to do that. Given the configuration, I don't even see any safe place to apply leverage with a tool that would tighten that belt.

I just managed to destroy another belt when the thing slipped on me, I'm down to my last Gates belt. I know it's a cheap item but not if it's the only thing you're ordering by mail. And something with better grip on the pulleys would be highly desirable.

I do recall someone saying they used another type of belt, one used for sewing machines. Well, there are several sewing machine repair shops in town, but the belts aren't listed by length, making selection difficult. Any info on those options?

someone mentioned using a 6" o-ring in a post somewhere.

I assume you've done this: http://www.cartertools.com/beltalign.html

Interesting comments here, but no simple solutions (search belt tension): http://www.janellestudio.com/metal/taig_mill_tips.txt
If you can stall the spindle, and not the motor at the same time, your belt isn't tight enough. We used to use these belts on big printers back in the late 70's. One adjusted so it sang as you plucked it would last for a year or more of use (27-7), while one that had an inch or so deflection mid belt may not last but a couple days. Slippage is a killer on these guys.


I can think of a few very awkward methods to increase tension with a screw and a right angle bracket say, but nothing actually usable. Maybe a two angled blocks sitting on that second screw (the one in the curved slot), one block fastened to the motor plate.

The Taig spindle motor is rated at 1/4 HP continuous duty. The means if will actually produce 1/4 HP all day long and much more than 1/4 HP for shorter periods of time. If your belt is slipping then I would suspect that you don't have your pulleys aligned quite right or your overloading the machine (the belt will slip before the motor bogs down.)

Oh yeah, it was that O-ring post. Don't especially like the sound of an o-ring, it's got no fiber reinforcement or anything. Kinda scary to put on there.

I went through problems with pulley alignment early on, then learned how to align it with squares. I'm now confident that it's aligned very well.

The belt's fine on the middle pulleys. But the extreme ratios it'll just slip when it gets a heavy load- I think before it can draw 1/4hp, and unable to produce the "brief surges of much more".

IIRC, someone did make a motor mount with some sort of tensioner, like a jackscrew that pushed it out. Which is a GREAT idea, although I don't remember that specific solution looking really elegant. Like most pulley mounts, it's a bit awkward because the mount's offset from the line of the belt so the force can cause undesirable distortion if you ask for high forces, but the belt's not all that big anyways.