Need Help!- How to change spindle ball bearing ?

[calor]

Hi,since a while the spindle of my CNC Vertical Center have some problem :
I apply an effort on the spindle ( X or Y ) and i measured the displacement with a fine micrometer gauge = between 0.15 and 0.2 mm of space.
Ball bearing is probably worn out or damaged.



Brand : KRYLE
Model : VMC 500 B
Year : 1991
Table : 750 x 450 mm
Spindle attachment : BT-40

Could you have a scheme or a plan of this kind of spindle ? i'm able to change the part but i don't have any plan of this machine. Someone can help me please ?

[mc-motorsports]

Can't help you with prints, but I do suggest if you don't have A LOT of experience rebuilding spindles, send it out for repair. I've seen where quite a few shops try to repair spindles them selves and it ends up costing WAY more money to recondition the spindle. Most of the time it's not as easy as just replacing the bearings. Bearings have tolerances like everything else and usually the thickness of the bearing can vary as much as .1mm from the same manufacture. Then if you use bearing from another manufacture...??? Everything has to be refitted to precision tolerances, bearing spacers may need to be reground to tolerances or .002mm flat and parallel ect. You generally need .03mm pressure for holding the bearings in place, too much will distort the bearing which can lead to problem, not enough and the bearing is loose or liable to spin. Then your going to need to balance the complete assembly and regrind the taper, and so on.

[bob1112]

I would agree it depends on your level of mechanical aptitude. This is not as easy as swapping axle bearings but it can be done. We have done it 3-4 times now. You can save some money if done right but can lose in the long run if some goes wrong or not fitted right.

[calor]

Thank you for all your replies and advice.
Finally the problem don't comes from the ball bearing but from a little space between the nose and the ball...I'm pretty sure because the sound at high speed RPM is close from usually. ( a damaged ball beatring made much noise at high speed ).
I will certainly disassemble all the nose spindle and post you some pictures if you found that interesting.

Thank you

[Mazaholic]

I agree with everyone else,replacing spindle bearings are not for the do it yourself people.
The bearing are usually made of ceramic and require a high level of cleanliness,and require a preload...Preload is not something you can do by feel,also the spindle may require a break in period..the rebuilder has machines for that,they mount the spindle in a machine and hook up oil lines and the machine runs thru a cycle to break the spindle in.

[mc-motorsports]

I've rebuilt thousands of spindles. Every one of them we just run it using a universal drive using the parameters for the motor/encoder and run it at 25%, 50%, 75% and 100% speed for 1/2 hour increments, let it cool down, balance it cold and then back to max speed until it hits max temperature and check the balance again. That part is easy.