Originally Posted by
Frederick Rowe
Noted that this was not specific to my post, but in my case my Unisaw was new and the belts were new - albeit mildly out of round. Certainly, comparing poor quality, worn, or in my case defective belts against a set of good quality non-defective belts is a faulty comparison.
To refine my point, besides that the Fenner belts work great and make a good alternative to traditional belts, is that new belts don't necessarily equal quality or that they don't have a set. Either of which would create vibration or noise under load. New saw owners who experience these symptoms should not assume that simply because their belts are new that they are not the cause of noise/vibration. The out of round condition of my Unisaw's factory belts were visually mild, but firm. I could see how one might deduce that the weight of the motor would easily remove the mild set and eliminate it as a possible cause of the noise/vibration.
The Gates brand belts which were factory installed on my saw took a set in the short time they were installed on my Unisaw. I carefully inspected them and found no visible signs of wear or other defect other than their oval shape. I carefully marked the apex of the set and rotated the three belts 120 degrees from each other to equalize the oval shape, and while this reduced the vibration and noise; it remained unacceptably high.
I'm sure had I replaced the factory belts with new Gates belts, not out of round, the saw would run fine - as Pete points out. I do believe that, given the design difference between traditional belts and the link belt, that the link belts are less susceptible to taking a set.
So, if you suspect your belt driven tool should be running more smoothly, look at the belts. Don't assume that just because they aren't horribly out of round, or that they don't have loose threads everywhere - that they aren't the problem. As for what you replace them with - there are choices, just don't try to solve it on the cheap.