Thanks for the replies guys, I'll have to see how it affects the plunge depth and I'll get in touch with Plate Engraving Corp. Thanks again.
"Damned LITTLE". Eyeball the exposed threads.
Diameter is whatever it needs to be, but the pitch isn't usually all that far-off what is used on Micrometer heads, and rotation can be but a scant few degrees.
Real-world use even as a new kid I could cut hearing aid PCB traces slick as Owl poop, eight hours a day with that Gorton dinosaurian.
Even by the tail-end of the 1950's a behind-the-ear hearing aid PCB was only about the size -and even shape - of an ignorant kidney bean, flat-sectioned. Mic, reproducer, and Silver-cell battery took up MOST of the space.
My present-day weapon of choice for intricate milling? Salvaged H.B.Preise Panto-engraver with good multi-axis control. All manual.
Wanted basic text and artwork data plates? I can order those cheap enough online, "CNC'ed", hot-stamped, or "Metalphoto", artwork right off the Pee Cee, and fast.
Panto-engraver is for "the harder stuff". Literally, what with die-grinder heads mounted.
Template need not even be metal.