Chinese 300W DC spindle - is the spindle shaft grounded?

[HankMcSpank]

So I had a look in my bearing drawer, which was totally empty bar one 8mm ID bearing - result......except there's no electrical continuity between this particular bearing's inner & the bearing's outer casing....



('scuse the crud - it's been a drawer for a couple of years!)


....and it ain't a ceramic type either! (i dunno you just can't get the bearings nowadays!).

Therefore I guess we can consider this case closed....clearly some bearings (even non ceramic ones) are open circuit whereas others seem fine (which could make sourcing ones that do have electrical continuity a bit of a lottery!)

Edit: Oh, BTW (as suspected) whilst 'neat', an 8mm ID bearing isn't a tight push fit....do you reckon a 5/16" (7.94mm) ID bearing fit ?