Lathe motor vibrates entire machine

[zeeprogrammer]

Thank you Gary for bring this up. And thanks to all the responders. I've been having similar issues and this thread is very helpful. 

[10KPete]

I've had a 'noise' in my 10K since I rebuilt it around 10 years ago. It's something in the lower drive unit that seems to be contacting the sheet metal somewhere under there. At least I'm sure that's what it is. It's nothing serious or out of balance but it sure is annoying.

This thread is pushing me to get under there and find/fix it.

I hope it's easy.....

Pete

[gerritv]

My approach would be more direct;

Mount motor, if no shaking
      Mount pulley to motor, if no shaking
           Mount belt to next pulley/idler, if no shaking
etc.
It could e.g. be a pulley with out-of-centre hole thus acting as an out of balance flywheel. Or a really badly made v-belt, with lumps.

You have already eliminated the motor itself from your previous investigations.

Given the simplicity of the drive train it doesn't seem worthwhile doing the 'binary search' approach that otherwise works so well.

gerrit

[Mcgyver]

I'm having a hard time following the story here.

25 years ago the motor ran smoothly off the lathe but created a huge amount of noise on the lathe, even without the belt disconnected.  Correct? 

That seems clearly a resonance and natural frequency problem....very small bit of vibration at the motor happens to be at the stands natural frequency, and like solders not breaking step on a bridge, the energy builds up and the magnitude of the wave increases.  To change a natural frequency, you have to change the stiffness of the stand (natural frequency is function of weight and stiffness) But how did we get to today and what is today's problem? 

you specifically say you took the belt off and it still did it - why are we considering chucks and belts if that's the case?

confused. 

[Stuart]

Your not the only one

Ok first is this a single phase motor ? Or three phase

Has the belt pulley been removed for testing ?

My first step would be motor mounted on lathe correctly , without the pulley , what happens , if you still get vibration it’s the motor ,if ok then put the pulley one and test

You have to start with only one variable at a time test and add each single component

If the motor is three phase how are you supplying it with power proper three phase from the power company or are you simulating it from single phase

If it’s single phase then these are not the smoothest device and it could just set up a resonance as mentioned by others
 One last point is the motor being powered with the same frequency as the name plate

Stuart