I needed a break from micro-machine design...
Back on this. Machine shop is swamped so I still don't have my quotes. But, it gives me more time to save money to pay them...
I needed a way to accurately rout for the VTA lock disc. Similar to the Michell "Finger Nut".
Anyway, this locates in the counterbore for the tonearm, and I will rout around the
outside of it, to create a circle of appropriate diameter, on center, and of proper depth. The edge of the disc will peek out the side of the plinth, just above the sub-plinth, for loosening and tightening. Not quite VTA on the fly, but at least you don't have to reach under the table, or prop it up on blocks, while fine-tuning... I will have a "wall" thickness of 0.165" on the back of the plinth, but it should be enough in Birch ply. I'll reinforce it with cyanoacrylate in that area, after I'm done with the routing.