Help! Spindle Bearing Noise

[petriej]

We have a YCM60 w/ AB Bandit 4 controller that gets use nearly every day. The oddest thing happened the other day.

I was writing a tapping program in G-code. (The onboard G84 does nothing but turn on the spindle for about 30 degrees of rotation.) Nonetheless, I wrote the program and after a test run of the program, the spindle started making the strangest noise.

I have never reversed the spindle before, and even at only 500 RPM with zero load it is making noise.

So does anyone have a similar experience? Is this the spindle bearing? Any thoughts? Anyone here change out a spindle bearing on an old YCM60??

I wasn't even in material when it happened, so I am just wondering what the deal is?

Also, does anyone know good feed/speed for roll forming 4-40 in Aluminum?

[philserveng]

this could be bearings, but you should also check drive the belts. to properly check the bearings release the belts and rotate the spindle by hand, is the noise still there ? do the bearings feel rough.check for runout using a 0.001mm indicator, check for lift in the bearings......there should be less than 0.002mm. by the way, have you got a poor surface finish?

[petriej]

Surface finish has degraded a tiny bit. But we are also running higher feedrates. Surface finish is now the cut lines from the tool. It was previously clean.

It seems to be the bearing on the top of the head at the drive pulley - I moved the quill to the end of its stroke and the noise stayed in the same place.