Delta Unisaw question?

[Roger Barga]

Has anyone experience a strong vibration when powering down their unisaw? Any thoughts on what might be causing this?

I recently assembled my Delta Unisaw, which had been sitting in a friends garage unboxed for about a year; we ordered our saws together but I had to rebuild my garage first. Anyway, when I turn off the power and the blade is slowing down, the saw will vibrate or rumble right before the blade comes to a halt; it's not violent but definitely would fail the nickel test. The saw both starts and runs smoothly, it's just the shutdown which seems off. I checked out my friends saw, since they are exactly the same, and it doesn't do this. Any suggestions on how to fix or trouble shoot this would be appreciated.

Thanks,
Roger

[Norman Hitt]

First, Retighten the belt and try it again.

[Hoa Dinh]

First, Retighten the belt and try it again.
Or the belts may be too tight. Try to adjust them either way.

[Norman Hitt]

Or the belts may be too tight. Try to adjust them either way.

That's possible, but I figured since he just started using it, the belts might have stretched a bit. It could be a pully that's loosened up or cocked on the shaft a bit also, OR the pullys might not be coplaner. One other thing that comes to mind is that the belt could be a little hard yet after setting for a year and the "Set" in the belt has not relaxed yet, which might not show up when pulling/under load, but could show up at a given rpm range when slowing down since it isn't under load at that time.

[JayStPeter]

The belts may also be set. Mine had that problem new. After setting another year you might need new belts.

Jay

[Russ Massery]

Sounds like the belts have "memory" in them. They have taken a shape from sitting. I would reccommend going to a "top cog" belt style. Or what I did is when to link belt. Not reccomended by some. But I myself and others who have used them have reported no problems. And the thump you hear will disappear.And the saw will run much smoother.

[Eddie Darby]

I had the same problem on my Jet Cabinet Saw. I tried the link belts, and I would say that almost all of it disappeared. There is still just a little bit of shudder just before the final stop. Much smaller than what the original belts gave.

[Jim Becker]

Same as Eddie for me. Belt set was causing a "bang" and some vibration after the saw sit for a few weeks un-used.

[Randy Gillard]

Do the saws have the same motor? My rebuilt General 350 does the same thing. It has a new Leeson Made in China motor that starts and runs great, but there is a shudder when decelerating. I think it has something to do with the centrifugal switch reclosing while there is still some residual magnetic field in the motor. One way to test this is to remove the belts altogether and run the motor solo. I just haven't gotten around to it. I put link belts on my saw and it is a non-problem.

[Roger Barga]

Thanks, I appreciate the suggestions... When I get an evening free this week I will open up the saw and look at the belt setup.

Cheers,
Roger

[Harley Lewis]

Roger, a couple things here.
1. Most folks do not recommend link belts on a uni since it is driven by a 3 belt system.
2. When my uni was new it vibrated a bit, and I was told the belts needed to break in. I cranked up the saw and let it run continuously for 30 minutes and it all went away.

[Andrew Ault]

Yeah, my Unisaw gets grumpy when it sits unused.

When I first got it, it threw a breaker when I turned it on.

Manually turning the blade a bit before turning it on did the trick.

Now that it gets used alot, no problems...but when I was gone a while I had to turn the blade manually again.

V-belts take a set when they sit. Lumpy on trucks and grumpy on unis.