Fixturing A Semicircle

[DIYSwede]

Thanks Rick for a very good walk-thru - very methodical and easy-to-follow write-up!

Apologies for probably stating some redundant and/ or undemanded info here:
The resistance contact measuring method is clever indeed, but shouldn't your entire mill be safety grounded?
I. e. The foundation and table should be grounded together with quill and chuck - and thus measure <1 Ohm.
Most chuck mount contact measuring devices I know of use this very fact to even function in the first place.

Having the quill/ chuck ungrounded developing a fault at live voltage, could mean real trouble.

Being a "concerned electrician" (amongst other duties) in a Arts Uni*, I'm on constant vigil in these aspects.

-Have fun and be safe!
Johan

*I could probably start an entire sub-forum with stories of "When Electricity meets Artist's Creative Juices"...
Saved quite a few BAs and even an odd PhD candidate from blind dates with Darwin (and Dunning-Kruger) thru the years.
"Sheer luck" is not a proper Health & Safety practice in any workplace.