5.95mm/.2345" Ball Bearing - Where Did I Come From?

Had one of the compression washers break on the stack of our 770M, so I decided to tackle the leaking seals on the power drawbar while there. No issues tearing down or rebuilding the PDB, or reinstalling the compression washers. However, while putting things back in their place, this little ball bearing was hanging out in the mix of random dust bunnies and rogue chips that were vacuumed out. It certainly meant for a .25"/6mm home of some sort.

tl:dr - Is this an important part?!

@Felicia_Plunkett That’s certainly a strange one.
How does the machine sound motion wise? Do the axes sound normal and move accurately?

Yes, everything is spot-on in the accuracy department, and the sound is similar to the mill pre-fix.

I am at a loss on this one. Where would a bearing that size be in this machine, if it would be there at all?

@Felicia_Plunkett The only balls around that size on 770’s are the ballnut, but even those are slightly bigger. If you have a borescope or other flexible camera I’d take a look at the seals of the ballnut, but even getting a good look at them is a chore. I think it’d be highly unlikely that the ballnut could have an issue that results in a bearing ball falling out without A) many more balls falling out or B) seeing some sign of the issue, either noise or backlash.


Norman, this is exactly what I was hoping to hear!! Thanks so much for y’alls time, and if anything comes up I will be sure to come back like a bad boomerang.

Thanks again!!

Enclosure door catch?

There is a prize if you also find the spring?