Sheave wobble

S

slow-poke

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I recently purchased an old LC-30 milling machine. Swapped the motor and ran it for the first time. All seems okay except the sheave attached to the motor has a noticeable wobble, I would estimate about 1/8".

I transferred the key from the old motor to the new. The shaft diameter of the old and new shafts are the same. There is a thin metal spacer that fits between the sheave and the shaft. It fits quite snug when installed.

Possibilities:
- Sheave has been dropped at some point
- motor shaft is bent, (I could check with a dial gauge, however it looks fine)
- The spacer is incorrect and needs to be a few mils thicker?
- Poor installation, not sure what I could have done wrong, however I never swapped a sheave before.

Advice and suggestions welcome
 
I had a noise after swapping out a motor. It was the motor pulley. I thought I had tightened the set screw, but it had come loose just a little. I re-tightened the set screw and the noise went away. Just FYI, a variable to eliminate. May not be your problem.
 
slow-poke said:
I recently purchased an old LC-30 milling machine. Swapped the motor and ran it for the first time. All seems okay except the sheave attached to the motor has a noticeable wobble, I would estimate about 1/8".

I transferred the key from the old motor to the new. The shaft diameter of the old and new shafts are the same. There is a thin metal spacer that fits between the sheave and the shaft. It fits quite snug when installed.

Possibilities:
- Sheave has been dropped at some point
- motor shaft is bent, (I could check with a dial gauge, however it looks fine)
- The spacer is incorrect and needs to be a few mils thicker?
- Poor installation, not sure what I could have done wrong, however I never swapped a sheave before.

Advice and suggestions welcome
Click to expand...

If the motor shaft is running true, your problem has to be with the sheave. It is possible thast a previous owner improperly used a puller or used a hammer to remove the sheave previously and it is out of alignment. If so, the simplest route may be to just replace it. It sounds like the wrong bore anyway. You shouldn't need to use a shim in the bore.
 
slow-poke said:
I recently purchased an old LC-30 milling machine. Swapped the motor and ran it for the first time. All seems okay except the sheave attached to the motor has a noticeable wobble, I would estimate about 1/8".

I transferred the key from the old motor to the new. The shaft diameter of the old and new shafts are the same. There is a thin metal spacer that fits between the sheave and the shaft. It fits quite snug when installed.

Possibilities:
- Sheave has been dropped at some point
- motor shaft is bent, (I could check with a dial gauge, however it looks fine)
- The spacer is incorrect and needs to be a few mils thicker?
- Poor installation, not sure what I could have done wrong, however I never swapped a sheave before.

Advice and suggestions welcome
Click to expand...


Remove the pulley and check the bore. I had to bore a pulley that was sloppily done with just a machine drill. The bore was oversize and caused a wobble. Apparently someone just drilled a 1/2" bore to 5/8". The scratches from the drill were apparent. I bored to .725 , Loctited a steel plug in the bore and then drilled, and bored to .6255 for the shaft.
The pulley ran without wobble afterwards.
mike
 
4GSR said:
Find you a sheave with a taper lock bushing and replace the old sheave with it. If you shop real carefully on eBay, should be able to pickup one for around $25 for both sheave and bushing. Ken
Click to expand...

Ken,

I was wandering around Princess Auto and found a taper lock sheave and it completely resolved the wobble and vibration. Thanks :grin:
 
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