Belt slippage on tablesaw question

[Chris Bruno]

Hi everybody,

I have the 22124 Craftsman tablesaw. Yesterday, I converted it to 240v as part of an ongoing reconfiguration on my workshop for an improved layout. When I tested it's new setup, the saw now makes a squealing noise for the first second or so after startup. It never did this before.

The saw now brings the motor up to speed instantly, whereas before it seemed as if perhaps there was a brief (very brief) ramp up before full RPM.

When I remove the blade, there is no squealing, so the added inertia of the blade appears to be enough to cause the squealing.

The squealing itself sounds very much like the belt slipping. The tension on the belt is only created by the weight of the motor in this saw. The belt is a 6 rib flat belt, not a V. I took the belt off to check it and it looks OK (no cracks, etc), though it is the original belt.

When it was still 120V, it was plugged into a 20A circuit, so total current available was really never a problem. I only ever popped the breaker when I had both the 2HP dust collector going and I was ripping 2.5" hardwood... Then, and only a couple of times ever, did the breaker pop. (Though the reason for the change is so that the dust collector can stay on the other circuit and T/S and Jointer will be on the 240v line that I ran. This way, I don't have to worry about ever popping the breaker during a cut.)

I'm going to check to see if perhaps somehow one of the pulleys may be slipping on its arbor, but I thought I'd post here and see if anybody else has ever heard or seen something like this. If its really a belt slipping because of some higher initial startup torque, then I guess I'll need to figure out a way to increase the belt tension beyond what the current design has.. hmmm..

-Chris

[Tom Hintz]

I would look at cleaning the pulleys and belt before trying to increase the tension. One of my old contractor saws developed a squeal I could not find and it kept getting worse over time. I finally removed the belt and wiped the pulleys and belt down with alcohol and the squeal went away for a while. It did come back a few weeks later so I replaced the belt (had some shinny areas on it) and that fixed it for good.

[Wayne A Hall]

I would replace the belt with a power twist link belt.

[Chris Bruno]

Hi Wayne - it's a flat ribbed belt (like the serpentine belt in your car)... Technically speaking, its already better than the powertwist...

[Lee Schierer]

Make sure your motor is free to pivot. Sometimes the bolts that make up the pivot for the motor are too tight and the motor essentially can't move to keep proper tension on the belt. Also check to insure the belt isn't too long (the motor should tip beyond where it stops with the belt in place).

[Myk Rian]

I would look at cleaning the pulleys and belt before trying to increase the tension.

+1. If the belt has developed a shine, replace it after cleaning the pulleys.

[Don Jarvie]

Change the belt. If your car has ever needed a new fan belt you get the initial squeak on start up and then it goes away.

Change the belt and no more noise.

[Howard Acheson]

How old is the belt? Belts will begin to slip as they get older.

Don't add weight or in any other way attempt to tighten the belt. It sounds like you have a contractor type saw where the weight of the motor provides the tensioning of the belt. Otherwise adding weight or tension may distort the trunnion mechanism or saw table top.

[Ray McGrath]

New belt + belt dressing
Ray

[Chris Bruno]

Thought I'd post an update for any future references.

I tried belt dressing with virtually no improvement in the condition, so I went through the effort of rearranging the adjacent equipment (attached router table) to allow me to investigate more deeply.

As it turned out, when the motor was starting, the instantaneous torque kick was briefly (but significantly) reducing the belt tension which was causing the belt slippage...

For testing, I tried hanging a 10lb gym weight off the motor and that didn't end up doing too much good.

And then I 'discovered' a kind of interesting element of my 'problem'. I was getting this slippage when I had the blade retracted completely.

In the design of my saw, there is a spring which provides tension against the pivot arm to which the motor is attached. The way it is designed, as the blade is raised this spring will provide a larger moment against the hinge arm. At the lowest position of the trunion, this spring provides essentially no moment.. So I was testing the saw in a position which it was most likely to be a problem. I raised the blade all the way up and it didn't squeal at all. When I raised it only high enough to cut 3/4" ply (probably what I do the most on my saw), it squealled, but a lot less than when fully retracted.

So I fired up the metal lathe and turned 2 little bushings that I could slide onto the 2 legs of the spring that essentially increased the preload on the spring. This still allowed some squeal at fully retracted, but it was gone at the 3/4" height.

After that, I went onto Steel City's website and checked into the owner's manual that they have for the Steel City branded version (same saw as far as I can tell). Except that Steel City offered a 3HP version.. It turns out, there's a different spring for the 3 HP version, which I thought was interesting. I may call them and ask them about it...maybe it will be even stiffer than my modded version.

Thanks for the advice!
-Chris