AL960 funny noise

[rfurzer]

I have been doing some low-speed screwcutting and notice that there is a vibration as the lathe slows down after switching it off. I did not particularly notice it before when doing higher speed work but it does it as the lathe slows from any speed when I checked it today.

It seems totally normal when actually running with no significant vibration even at the slowest setting.

I wonder if it is the spindle bearing

Am I worrying about nothing?

P.S the AXA toolpost is going very nicely

[.RC.]

Often you find high speed shafts/gears will resonate and vibrate at a certain speed, and they will not vibrate at any other speed...

[Dave J]

If it seems fine when running, I don't think it will be the bearings.
I would change the belt first, most of these machines are supplied with cheap belt's.

Dave

[rfurzer]

The advice about the belt jogged me into action. I had just replaced the belt as the stock one is a bit short to easily get into the slow pulley (in fact the size specified on the belt is right- It is actually a size smaller than marked!).

To get the belt onto the slow pulley it is necessary to remove the 120/127 gear (I hope that the designer has been sent to the salt mines).

Anyway, I have just had a bit of a play round and found that the noise is coming from the gear train. I had not properly adjusted the mesh when I put the 120/127 back on

Properly adjusted, all is sweet.

[Dave J]

Good to hear you got it sorted.:2tsup:

Dave

[Gavin Newman]

I agree, the belt change is one of the few niggles with the 960B, I tend to leave mine in low position as the slowest speed in high range is too fast for screw cutting and I do a lot of that and parting off. The size marking on the belt is confusing. According to the local bearing & belt bloke, the Taiwanese & Chines measure the belt length at the bottom of the pulley groove whereas the poms and yanks measure it halfway up the side of the pulley sheaves - hence the different markings.

When I set the mesh for the 120/127 gear I use a piece of thin paper between the gears to set the gap. It' an old trick but it works for me, I generally use a bit of newspaper.