Thread: lathe vibrate at lower speed

Originally Posted by thorens

i just set up a AL960b type lathe and got a vibration on lower speed setting . at maximum speed it have minimal vibration but noticeable at lower speed setting . the lathe have been leveled with machinise level . anything's I should look at to solve this problem?

cheers
Peter

With or without chuck mounted?
Which speeds in particular?

Originally Posted by Gavin Newman

With or without chuck mounted?
Which speeds in particular?

good day Gavin.
it is with chuck mounted more so with stock chucked .the vibration speed was 640/900RPM.
any idea ?
Peter

Hi Peter,
Are you running of a vfd? If so when you say low speed do you mean low Hz or gearing or both?
Cheers,
Ew

Originally Posted by Ueee

Hi Peter,
Are you running of a vfd? If so when you say low speed do you mean low Hz or gearing or both?
Cheers,
Ew

Hi Ew.
no this lathe is 240v and it is geared head.
Peter

I would say it is the resonant frequency that it vibrates at...

So if you remove the chuck does the vibration cease?

I'm assuming you are using the standard 6" 3-jaw chuck - have you tried it in each of the 3 possible mounting orientations?

So you get the vibration in the 2nd and 3rd speed in fast pulley, any difference if you run it on the slow pulley, especially in the 1st speed (650)?

Originally Posted by Gavin Newman

So if you remove the chuck does the vibration cease?

I'm assuming you are using the standard 6" 3-jaw chuck - have you tried it in each of the 3 possible mounting orientations?

So you get the vibration in the 2nd and 3rd speed in fast pulley, any difference if you run it on the slow pulley, especially in the 1st speed (650)?

yes i do use the 6" 3 jaws .it is D1-4 mount. do you means rotating the back plate to the chuck or rota the back plate to the head stock mount ? i will try it wthout the chuck and see what the different it made and try different setting on the pulley.

Peter

Originally Posted by thorens

yes i do use the 6" 3 jaws .it is D1-4 mount. do you means rotating the back plate to the chuck or rota the back plate to the head stock mount ? i will try it wthout the chuck and see what the different it made and try different setting on the pulley.

Peter

I would try without the chuck 1st to see if the out-of-balance is coming from the chuck or the rest of the lathe. And maybe the motor minus the belt.

I meant trying the chuck to the spindle positions (my 960 6" chuck is direct mount), did you have to fit the back-plate to the chuck or were they pre-assembled?

Originally Posted by Gavin Newman

I would try without the chuck 1st to see if the out-of-balance is coming from the chuck or the rest of the lathe. And maybe the motor minus the belt.

I meant trying the chuck to the spindle positions (my 960 6" chuck is direct mount), did you have to fit the back-plate to the chuck or were they pre-assembled?

will do all that .
i refit the back plate to the chuck as it was having too much runout . may i try re-posiition the check to the spindle first and see what it does.
Peter

ok.
I confirm that the vibration i'm getting is mostly from the chuck .
Peter

hi peter. so wih no chuck its running smooth? is it as bad with the chuck as it was yesterday?

Has this lathe been used by yourself prior to this fault arising?

If you have used this lathe prior to the fault what was the surface finish like on turned stock?

If the lathe was not used prior to this fault surfacing , what type of surface finish are you getting?

One of the many differences between a good and a low cost chuck is, how well it is balanced. Especially if it is a chuck with backplate (as opposed to direct mount). And again especially if it is a cast iron chuck (as opposed to a steel chuck). Maybe this article contains some useful hints:
Lathe Vibration Issues

Originally Posted by azzrock

hi peter. so wih no chuck its running smooth? is it as bad with the chuck as it was yesterday?

Hi Aaron.
yes it run much smoother when no chuck on .
Peter