Table saw: What just happened?

[Robert J. Bonn]

This has me stumped. I was cutting a piece of half-inch plywood, about 15" wide, on a contractor-type table saw. With an inch or two to go, I heard a sound that seemed louder than normal. I completed the cut, and as soon as I did, the saw began squealing louder than I had ever heard before.

I shut it off and investigated. Nothing unusual on top, but when I looked at the back, I saw the motor was hanging all the way down.

Two things looked wrong to me. First, on this kind of saw, the motor pivots. There's a screw in a slot that's supposed to keep it from pivoting down too far, but that had broken off.

But why was it able to do that? Shouldn't the belt have held it in its normal position?

Everything else in the back and underneath was completely tight.

I use a link belt on this saw, and it sure looked as if the belt had suddenly gotten longer. As an experiement, I removed six links, and put the belt back on. I put a new screw in the pivot slot. I made a couple of small test cuts, and it worked fine.

Does anyone have any idea what happened? I can't believe that a link belt would suddenly stretch that far, but with nothing else being loose, I don't know what else to think. Anything I should check for?

[rjbonn]

This has me stumped. I was cutting a piece of half-inch plywood on a contractors' table saw. The piece as about 15" wide. I was most of the way through when I started to hear a sound that was a little louder than usual. I completed the cut, and as soon as I did, the saw began to squeal very loudly.

I turned it off and checked. Nothing wrong on top, but when I looked at the back, I saw that the motor had fallen all the way down. The motor pivots, and a screw in a slot usually keeps it from dropping too far. The screw had broken off. But of course, gravity usually keeps tension on the belt, and the belt holds the motor up.

I checked everything I could. All screws were tight. The motor mounting plate appeared to be in the same position as usual. But the belt was suddenly way too long to hold the motor up. (The squealing sound was the belt rubbing against the saw housing.) I use a link belt on the saw, so I tried removing six links. When I put the belt back on, the motor was back into its usual position. (I replaced the broken screw too, even though it doesn't actually hold anything). I tried making a couple little test cuts, and it seems to be fine.

Can anyone explain what happened? I had been using the saw all afternoon, and everything had seemed fine. I can't imagine that a link belt could suddenly become a lot longer, so something else must have happened. Can anyone think of an explanation? Is there anything I should check before using the saw again?

[Limp Arbor]

I'm not familiar with the link belts but if nothing loosened up then my guess would be one of two things.

1) The belt was never fully tight and the motor was resting on the screw. The screw backed out and the motor dropped all the way down. I find this scenario unlikey because if the belt was never tight you would have had squealing or slipping at some point. 2) The belt 'wore in' and dropped all the way down into the pulley grooves. Again I don't know about link belts but a regular belt should not bootom out in the pulley. There should always be a slight gap at the deepest part of the pulley when the belt is fully seated. Are you using pulleys specifically for the link belt?

Check your pulley alignment carefully. This can be a PITA on a Contractor saw but a framing square or some other straight piece of metal should let you know if they are lined up or not. The pulley on the motor should be adjustable on the shaft to line things up.

[Edwin Pawlowski]

My guess is the motor was sagging for some time and the belt was holding it, slowly stretching. Finally reached the point where something made contact and you heard the result. When was the last time you looked at the belt? If it was the same time I checked mine, it may have really stretched.

[Leon]

The arm assembly that the motor hangs on is adjustable in and out. closer and farther out from the saw. This allows for adjustments if the belts stretch. Usually the adjustment is at the trunion. It could feel tight but it still could have slipped.

Or your link belt did form into a more final length.

[Tim]

If the saw in question is a craftsman model, I think I know what happened. I had one a while back that did something close to that. The motor mounting plate cracked diagonally, allowing the motor to twist, which shortened the distance between the motor and arbor pulley. The part (cast metal plate which the motor is bolted to, springs, and two metal rods that connect it to the saw) was something like 12 bucks from sears. I chose to epoxy and bolt a 1/8" steel plate on the back of their casting rather than buy another part. (If the first one broke, why wouldnt the second?)

Hope that helps.

-Tim

[Bob Alexander]

I had the same thing happen with my Grizzley saw. The Link-belt seemed to stretch and I had to remove several links to make it fit again.