Sunday, April 18, 2010

#12- Is there a ‘whole lotta shakin goin on’?

Not in California or Haiti – Although, that was the case recently when the Earth decided to move underneath them. I’m talking about wheel vibration in your stationary Bandsaw. Usually they are a 12”, 14”, or 16” size. For the purpose of this column, I’m talking about those Bandsaws that have a drive belt from the motor to the bottom wheel.

So, let’s say that you have one of those Bandsaws and you’ve always noticed that it seems to vibrate rather bad while you’re using it. You’ve taken the blade off and run it with just the bottom wheel in action and it still ‘shakes, rattles and rolls’. Or maybe you took the blade off and just running the bottom wheel shows that it runs as smooth as a Hunter ceiling fan. What to do?

First off, isolate the vibration – chase it down. If your saw is vibrating, take the blade off and run just the motor and the bottom wheel. If that smoothes it out, your problem is in the upper wheel. If you run the bottom wheel only and it still vibrates, the problem is in the bottom wheel or the drive system. Take the drive belt off and run just the motor. If it still vibrates with only the motor running, check the tightness of the motor pulley. If the pulley’s tight and yet it still has excessive vibration with only the motor running, I’d suspect you have a bad motor.

From this point, let’s say it smoothed out after you took the blade off. You’ve got the wheel guard open, so you can get to the top wheel. Give the wheel a good spin - enough so that it can rotate for at least 10 revolutions. When it finally stops, make a witness mark at the bottom of the wheel so that you can see it. Give it another good spin and let it stop again. Check where your witness mark is. If the mark is close to the same spot at the bottom, do the spin test again and see where the mark ends up. Do this 5 times and if the mark ends up stopping in the same area at the bottom of the wheel 3 times out of 5 tests, your top wheel is off-balance and needs to be replaced.

The test for bottom wheel balance is the same, but you will need to remove the drive belt before the test. The idea is to spin just the bottom wheel, not the motor and drive belt, too.

Send your questions or comments to: and we’ll see what we can do to help you.
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