Z axis mystery solved

[HuFlungDung]

I souped up one of my knee mill retrofits today, by changing the spindle drive pulleys into an overdrive ratio.

So, everything went well for a few hours, although the spindle did warm up pretty good after all day. Suddenly, I got a Z axis drive fault.

"Oh great, the top bearing got too hot and seized the spindle in the housing", I thought.

So I let it cool off overnight, came in in the morning, and right away, a Z axis drive fault, whenever the spindle went down about 4 inches. So, I tried moving the axis down manually, and yes, there really was something hitting!

So I opened up the quill box, and be darned if one of the bolts attaching the spindle yoke to the ballscrew had worked loose, and was standing on its end in the bottom of the housing, right where the ballscrew nut would bottom against it.

The other bolt was loose a bit too, but strangely enough, I had been feeding in a Z+ direction all day, so never noticed the slack.

Am I lucky, or what?

[balsaman]

Quite the detective work Hu!

Eric