Delta Unisaw #5: Motor update

What do you call too much vibration?

Jerks on startup? Vibrates too much while running?

If you put a half filled glass of water on your saws table does it slosh out?

-- Gary, East TX -- The longest journey begins with a single step.

“The only thing I can think of to do now is to pull the rotor out of the motor and have it and the pulley balanced together.”

I’ve never been blessed (or cursed) with a unisaw, and maybe I’m misunderstanding, but can’t the entire motor and pulley be balanced as a unit? The rotor, being the center rotating part of the motor, would seem impractical to me to pull separately.

BTW, sure seems like the balancing by the machinist should have squared it away already. Maybe one of those steel pulleys is the way to go.

-- It's not that a craftsman never makes mistakes, he just makes it look like it.

Kevin, try taking the belts off the motor, then turning it on. If the vibration is coming from the motor you will still have the vibration. If not then it’s your belts or arbor that needs the work. The link belts will cut down on your vibration some.

-- Tim -- http://tmuli.com

There’s a possibility you may have a bent shaft, so when you add the pulley,

the weight of the pulley amplifies the vibration..

You can check this out with a dial indicator, if you have one.

Otherwise, you can also just view it while turning it by hand.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

Tim, this is all happening with the belts removed.

Dick, I hope you are wrong because that sounds expensive. I couldn’t tell any movement by looking at the shaft. I may try the dial indicator tonight just in case.

Copperjock, it has a cast iron pulley on it now. The machinist would need the rotor and pulley seperate from the motor to put t into his machine.

GaryK, I don’t know, maybe I am being too picky. I have always heard that Unisaws shouldn’t vibrate much at all. I can stand a dime on the cast iron top and it will not fall over through starting, running, and stopping the motor. With the pulley on it, a nickle will not stand. I can get a nickle to stand on my Ridgid contractors saw even. I may have to try to get a video of it and that might help.

-- Kevin, Wichita, Kansas

I think you’ve about got it narrowed down, Kevin. Check it with the dial indicator and if its good, toss the pulley.

-- Tim -- http://tmuli.com

Did you ever check your blade, it could be out of balance.

Sorry! forget about it I just re-read your last answer.

-- -** You are never to old to set another goal or to dream a new dream ****************** Dick, & Barb Cain, Hibbing, MN. http://www.woodcarvingillustrated.com/gallery/member.php?uid=3627&protype=1

I just got off the phone with the machinist. He said to pull the rotor and bring it and the pulley in and he’d balance them together.

I think I’ll go ahead and bring the arbor and that pulley in at the same time just to be sure.

-- Kevin, Wichita, Kansas

For some reason this sounds like it’s getting a lot more complicated that it should be.

-- Gary, East TX -- The longest journey begins with a single step.

I agree completely. More complicated and more expensive than I would have guessed.

-- Kevin, Wichita, Kansas

Just think all I wanted to do was put new belts on it to start with.

I would have bought new pulleys, but I never found any for a Unisaw. I found plenty of the single pulleys for a contractor type saw, but no steel pulleys for a three belt Unisaw.

-- Kevin, Wichita, Kansas

Have you called Delta?

-- Gary, East TX -- The longest journey begins with a single step.

I would carry the pulley to an electric motor shop and let them sell me a new one. I have never seen a motor that had to have the stator balanced that didn’t wear out bearings every week, regular use mind you.

A pulley is easily warped or worn by heat which usually goes back to a belt issue, loose, too tight, worn, sized wrong, ect. If the pulley is worn then you may as well replace all of them as they will have problems also.
Just out of curiosity, why is a machinist working on your electric motor? Seems to be the wrong trade no matter which end he is grinding on.

-- .

I did contact Delta and went to the local Delta store. They both claim to have very little problems with their cast iron pulleys. They were willing to order new pulley for me. I thought I’d try this electric motor store in town first because a few of the guys in our local woodworkers guild recommended them.

The electric motor store told me they also could order me new pulleys but that they usually sent them to this local machine shop to get balanced instead. It would be cheaper since my pulleys show no sign of wear.

In talking with the electric motor shop and the machinist they both thought I should take the pulley and shaft to the machinist together and he could balance the pulley to the motor.

I don’t know what I should do. I have had a lot of suggestions by different parties.

-- Kevin, Wichita, Kansas

Just to make this clear to everyone that might be jumping on late I’ll update you.

The problem has been narrowed down to the motor and motor pulley. All belts, arbors, blades, mounting brackets, ... have all been checked and removed from the issue as of right now.

The saw has virtually ZERO vibration in it when the motor is running with the pulley removed.
The saw vibrates much more than it should when the pulley is on the motor.
The motor has brand new bearings in it. It made no change in vibration.
The pulley was balanced at a machine shop. There is no difference in vibration.

The machine shop and electric motor shop have suggested that I remove the rotor and bring it along with the pulley and key back to the machinist so that he can balance the pulley on the rotor. There maybe a difference between my rotor and his shaft that he balanced the pulley on.

If I can figure out how, I will post a video tonight of the saw running with the pulley and without so you can see what I am talking about.

Thanks for the continuing help on this. Eventually we will get it licked I bet.

Why haven’t i just bought a new pulley already? I don’t know if it will help or not and I’ve already invested a lot of time and money into this one.

-- Kevin, Wichita, Kansas