Single Phase Motor Vibration?

T

Tecnico

(Dave)
Hi

I'm looking for some advice on tracking down a vibration in the 1 HP single phase Baldor motor that came along with my SM 1120 lathe. It's vibrating more than I'm expecting so I'm looking for suggestions to track down the cause & fix it.

Baldor Cat 1310
Spec 35D11Y168

When I say vibrating more than expected I mean when it's (solidly) mounted to the lathe as was the original 3 phase motor, things vibrate and shuffle around on the chip tray and it's noisy. This is with or without the belt attached. It acts like it's out of balance - sort of**

So far I have re-greased the bearings, then washed the bearings out and lubricated (for test) with light oil. With light oil the motor still has about the same vibration and it takes longer to spin down. I don't think it's a bearing issue, they don't seem notchy or too loose either, maybe .001" radial play - hard to measure.

I've put the armature up between centres on the lathe and I see about .003" total runout when indicating on the armature laminate stack and much less on the shaft at the ends near the bearings. Is that enough to be of concern? No foreign material in the holes in the armature and the cooling fan is intact - basically no obvious reason for it to be out of balance.

The last observation is that the vibration is much less when the power is cut and the motor is winding down which seems to point at something electrical/in the fields???? The motor has a start capacitor only, not run.

What to look at next??

Thanks,

D :cool:

P.S. I've seen all the discussion WRT 3 phase and VFDs, it's all good stuff but right now I want to get this thing up and running before going off on another tangent that'll slow the process. That and deals on 3 phase motors don't grow on trees in this neck of the woods.......;):(
 
DavidR8

DavidR8

Scrap maker
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Are you able to check static balance of the armature while it's between centres?
I have a 1 hp Baldor (likely same spec) that came off a table saw. It is completely smooth at all times.
 
Susquatch

Susquatch

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Tecnico said:
The last observation is that the vibration is much less when the power is cut and the motor is winding down which seems to point at something electrical/in the fields????
Click to expand...

Have you looked to see if any of the stator windings or electro magnets are loose? It is not uncommon for this to happen. It's usually the first step toward motor failure. You might be looking at 3ph a lot sooner than you expected.
 
Tom Kitta

Tom Kitta

Ultra Member
Motor is connected to some kind of pulley on which the belt rest, no? See whatever it vibrates with that thing off - just the bare shaft.

Generally motors do vibrate - they key is "how much" is within specs - if possible compare to another motor at least visually or make video and post it for others to see - this way people can tell whatever it is excessive or normal.

Generally you should easily tell motor is running when you put your hand on it. Generally motor should not vibrate even close to the amount needed to say walk off the table.

Replacing bearings is cheap - like $6. You can spend more like $10+ for a pair and get rated bearings - but this should not be needed for a motor. If you were in Calgary I would offer lots of motor options - heck, you could upgrade to 2hp for example. 3ph motors are generally cheap as industry gets rid of them & that are like 1/10 or less in price.
 
T

Tecnico

(Dave)
DavidR8 said:
Are you able to check static balance of the armature while it's between centres?
I have a 1 hp Baldor (likely same spec) that came off a table saw. It is completely smooth at all times.
Click to expand...

There is too much friction in the spindle/tailstock to try and check balance, I'd have to pull at least one bearing to set up on edges but I don't think it's a balance thing because it has a lot less vibration when the power is cut.

Susquatch said:
Have you looked to see if any of the stator windings or electro magnets are loose? It is not uncommon for this to happen. It's usually the first step toward motor failure. You might be looking at 3ph a lot sooner than you expected.
Click to expand...

I'll have to look closer, on first inspection I didn't see anything noticeably loose.

Interestingly for new motors 3 phase seems less costly.....

Tom Kitta said:
Motor is connected to some kind of pulley on which the belt rest, no? See whatever it vibrates with that thing off - just the bare shaft.

Generally motors do vibrate - they key is "how much" is within specs - if possible compare to another motor at least visually or make video and post it for others to see - this way people can tell whatever it is excessive or normal.

Generally you should easily tell motor is running when you put your hand on it. Generally motor should not vibrate even close to the amount needed to say walk off the table.

Replacing bearings is cheap - like $6. You can spend more like $10+ for a pair and get rated bearings - but this should not be needed for a motor. If you were in Calgary I would offer lots of motor options - heck, you could upgrade to 2hp for example. 3ph motors are generally cheap as industry gets rid of them & that are like 1/10 or less in price.
Click to expand...

The bare motor with no pulley, sitting on the bench, vibrates pretty well so it's not anything to do with accessories. Comparing this to a 1/2 HP motor I stuck on to compare vibration the 1/2 HP is hardly noticeable as expected.

Yeah, bearings are not expensive and I have scoped out supply but I'm not inclined to spend the $30 for name brand (not keen on no-name Chinese if I'm going to the trouble to replace them) unless I think that's the only problem.

We need a teleporter to bring some of that good western gear out to these parts.......might even be cheaper to mail a motor than go shopping here.:(

Thanks for the feedback!

D :cool:
 
Tom Kitta

Tom Kitta

Ultra Member
So here is practical test - put the motor on your desk, connect power. Let it get to full RPM over a second or two. Now disconnect power. Does it vibrate? If yes, it suggests a bearing or simialr mechanical issue is the problem. If not, then its electromagnetic issue - such as uneven air gap.
 
T

Tecnico

(Dave)
Tom Kitta said:
So here is practical test - put the motor on your desk, connect power. Let it get to full RPM over a second or two. Now disconnect power. Does it vibrate? If yes, it suggests a bearing or similar mechanical issue is the problem. If not, then its electromagnetic issue - such as uneven air gap.
Click to expand...

The bare motor with no pulley, sitting on the bench, vibrates pretty well under power so it's not anything to do with accessories.

The vibration is much less when the power is cut and the motor is winding down.

Talked to (an older) gentleman at a motor repair shop and he doubted loose windings but would diagnose for $100. He thought that .003" runout on the armature laminations was a lot.

D :cool:
 
M

mbond

Well-Known Member
Premium Member
In my opinion, .003" is tiny. You likely have a short somewhere in the windings. The result would be a repetitive cycle of armature decelerating and accelerating. Causing a vibration around the line frequency - nominally 60Hz. Could your vibration be at that frequency?

If that's the case, it isn't easy to fix. You have to rewind the motor and it is probably better to get a new one
 
Tom Kitta

Tom Kitta

Ultra Member
I have one of these growler things to check motors. Never actually used it - but I have it.

With 1hp, these things are cheap enough to just scrap this one if something is off and get a new one - unless its something crazy like special C face etc. You should get 1hp to 1.5hp used motor for under $100 or at most $100.

Agree that if it is going away when turned off it is electrical in nature and could be a short in the winding.
 
W

wmetfab

Well-Known Member
Hi,
I priced a new Balodr 1 hp at the motor shop ive dealt with for over 40 yrs it was over $700!
They offered me a chineese knock off for around $400.
If anyone has an option or knows good place to get one let us know.
I found a 3600 Rpm on vanc island for $100 all I've found so far

I need 1 hp 1725 single phase reversible.
 
YotaBota

YotaBota

Mike
Premium Member
Might be worth giving Lenmark a call.

I bought a 3/4hp for my SM9 a few years ago from them for $100 NIB. I pled poverty and asked them what they had that might be surplus or old stock. He found a motor in my specs and asked me how much I could spend, I said $100 and he wrote up a bill that included tax.

@Tecnico - I think I would gamble the $30 and put new bearings in the motor. If it doesn't fix the vibration you could always pull the new bearings and them them for a future project.
 
T

Tecnico

(Dave)
I’ve been through the windings and no shorts, winding to winding or to the case and no open circuits in the windings. Of course that wasn’t running and not with a megger. (Man, iPads hate that word, keeps changing it)

Yes, I’d say the vibration is 60 Hz.

The guy I talked to thought he could get me a motor for $300 and had no used. I saw some about that much on line. I’ve seen used motors on kijiji for $100 but they were 1/4 HP lol!

I’m thinking seriously about throwing some bearings at it as a long shot, there may be a bit of play in the back bearing. Not really much else to do without going into the windings.

I might also look at a DC motor from a treadmill, I have a couple of 2.5 HP on the shelf. Of course that’s more work to set up a power supply……..

D :cool:
 
Susquatch

Susquatch

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wmetfab said:
I need 1 hp 1725 single phase reversible.
Click to expand...

1HP motors are everywhere for 50/60 bucks. Just do a Kijiji search.

Pretty sure I have one you can have. Shipping won't be cheap though. You will have to adapt the mounting. Where are you?
 
Susquatch

Susquatch

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Silly question.

Can you hear the contactor closing as it spins down?

It is possible that the contactor isn't opening as it spins up so the start winding is staying engaged and throwing things off balance a bit cuz it's fighting the run windings. Normally, you can hear it make a clicking sound as the motor slows down.

If it has two capacitors, the run cap might also be defective. They don't normally cause vibration but stranger things have happened.
 
T

Tecnico

(Dave)
YotaBota said:
And even with the vibration you can still use the lathe for making the sleeves and stuff for the DC conversion. :)
Click to expand...

Even better, I still have the Myford so I've got that covered. I'd probably have 60 Hz chatter over anything I'd do with the 1120 and that motor.;)

D :cool:
 
Last edited:
T

Tecnico

(Dave)
Susquatch said:
1HP motors are everywhere for 50/60 bucks. Just do a Kijiji search.
Click to expand...

Hah! Maybe they grow on trees in southern Ontario but in these parts not so much!

Susquatch said:
Silly question.

Can you hear the contactor closing as it spins down?

It is possible that the contactor isn't opening as it spins up so the start winding is staying engaged and throwing things off balance a bit cuz it's fighting the run windings. Normally, you can hear it make a clicking sound as the motor slows down.

If it has two capacitors, the run cap might also be defective. They don't normally cause vibration but stranger things have happened.
Click to expand...

The centrifugal switch is working. I actually set up an experiment to isolate the (only) start cap while running to verify whether it made a difference - as expected, no effect.

We do this stuff to learn, so far I'm learning everything that doesn't identify the problem, LOL!

Back to the shop.

:cool:
 
W

wmetfab

Well-Known Member
Susquatch said:
1HP motors are everywhere for 50/60 bucks. Just do a Kijiji search.

Pretty sure I have one you can have. Shipping won't be cheap though. You will have to adapt the mounting. Where are you?
Click to expand...
There are a lot of used motors on Kijiiji. Too many.
1 hp... 3 phase 460v or 3600 rpm.
Lots larger or smaller.
The one i want seems to be elusive.
Ill keep looking
 
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