Series 1 CNC Loose Z Axis

[keebler303]

A while back I noticed some free play in my Z axis while drilling some hardened material. It seems like the whole ballnut assembly can be pushed up 0.020" or more. The picture shows the top of the ballnut assembly. The whole thing moves up and down in the casting when I push up on the Z. The bearing locknut is tight, couldn't loosen it or tighten it when I tried. What is going on?

Thanks
Matt

[machintek]

Maybe the bearings are bad or someone replaced them putting in the wrong ones or not putting them in correctly.

George

[keebler303]

Are these AC bearings? Maybe the spacer size is incorrect so the bearings are free to move axially? How does one go about holding the ballnut still while trying to loosen the bearing locknut on top?

Thanks
Matt

[cnc4cheap]

Matt,

That type of head is very finicky and warrants a qualified technician for service work. It could very well be that an unqualified person has been into the head and possibly reloaded the ball quill with the wrong size or grade of bearing balls.

C4C

[keebler303]

C4C

Thanks for the reply, the play is not in the nut itself but rather between the nut and the casting (bearings). I can see the whole nut move up and down when I push up on the spindle. I've been too busy running the machine to take it apart. It doesn't really seem to effect anything unless I'm plunging into something hard or using a big drill bit. For all the smaller stuff, the weight of the quill seems enough to keep it in the right place.

Matt