Bill
I don’t understand.
You draw an arc at 222 mm.
You figure out where (on the 222mm arc) the counterweight will fit (when in the arm rest) inside the dust cover when closed
You drill a proper sized hole.
Lewm
Then, you ascertain the specs for THAT ARM
overhang _____
inner null point _____
outer null point _____
The makers have specific recommendations
ANY protractor with a variety of lines can work for any cartridge.
No math, no calculations, just twist the cartridge (retaining proper overhang) and make the best compromise of the two null points you can and tighten the screws.
It’s ridiculous how long it took, how much persistance was needed, to get the simple answer.
Now, if anyone asks, we can help them mount a non-rega cartridge in a rega arm!
I like helping people, that’s why I was hell bent on getting the simple measurements.

