Troubleshooting Table-Saw Motor Vibration

      Could be the pulleys, the belt, or the motor itself. September 17, 2008

Question
My table saw has had a vibration problem from day one. I have had the motor off the saw with only the pulley remaining mounted and there is still vibration. The pulley and both motor bearings have been replaced with new and there is still vibration. What should I do next?

Forum Responses
(Solid Wood Machining Forum)
From contributor G:
Does it vibrate if you turn it on without the drive belt? I have seen out of balance pulleys causing vibrations.



From contributor J:
While checking, inspect the drive belt - they can cause vibration if they are defective.


From contributor S:
Try a dial indicator on your arbor.


From the original questioner:
To further clarify, the motor has been removed. It has a new pulley, and bearings. Running independently from the machine with the new pulley and bearings, it still has a vibration. Can anyone out there diagnose the problem, or hint at a good solution?


From contributor S:
If you have had this problem from day one, have you contacted the company that you bought it from? Use up the warranty while you have it.


From contributor C:
You have to do the test in steps.First, you run the motor with nothing on it. No pulley. If it vibrates, put a dial indicator on the arbor and see what the runout is. It should be .0015 at the max. If it has more runout than that, there is your problem. If it vibrates, but there is no runout, I would suspect the rotor itself. If you have had it off, it probably is not in balance.

If it runs smooth, the put the pulley on it and run it. If it vibrates, then it is the pulley. If it is smooth with the pulley, then add the belt. Here it gets a little more difficult because the belt has to drive the driven pulley so vibration at this point could be either in the belt or the driven pulley.

If you are not sure you know how to inspect the belt, get another and see if it runs the same with both belts. I assume that you replaced the bearings with the proper bearing and that the bearings have the proper fit in the bearing housing. I also assume that you put the end bells back on exactly as they were originally.



From contributor R:
What make and model saw is it? The "contractor" style saws will probably never run as smooth a unisaw or pm 66 due to the design, particularly the motor mount. You could also try a powerlock link belt which may help. You should also verify the pulleys are in correct alignment.


From the original questioner:
The saw is a General 350. The belts have been replaced with brand new ones - a matched set. The pulleys are aligned, and there is about 1/4 - 3/8 " deflection in the belts.


From contributor C:
When I broke a belt on my contractor saw I went to Napa and they gave me a green belt. I put it on, turned the saw on and it shook so hard it tripped the breaker on the motor. I went back and asked for a black belt, they told me their computer picked that belt for my saw for heat buildup, and if my saw vibrated there was something wrong with my motor or pulley. I got a black belt anyhow and put it on and it runs smooth. At a friend’s shop I saw his W&H moulder running with a green belt on and it was shaking so hard it was walking across the floor. If there is any chance your belts are the green ones that could be the problem.


From contributor Y:
I've got a General 650 (same saw but left tilt) and it's silky smooth. You know the nickel test? I can stand a dime on it while running. Just to clarify your clarification - you ran the motor without the belts on and it still vibrated? That surely sounds like the motor, and personally I wouldn't troubleshoot it any further than that.



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