I'll usually touch off the cutter on part of the work surface that's going to be cut, but if I'm concerned about marring the surface I'll use a feeler gauge, feeling for a slight drag.
Person could have a lot of effort invested in a high-precision part, go for the
last surface or complex feature that actually could be make or BREAK "get paid" ELSE "scrap and start-over" - wasting all the prior investment in it.
Slab it into a sandwich.
Same alloy, either side.
Mill away adjacent.
Don't even
touch the "money."
Adjust with depth mic. Even gage blocks.
The scrap doesn't get to "vote". The money-piece rules the day.
Your mill will not HOLD across that modest span?
Pilgrim?
You are bidding the wrong sort of work for a wore-out manual mill, aintcha?
Just grip yer own guts in yer front teeth, bite down HARD, and do the best you can.
Know the many helpfuls. Use the bestest fit, any given tasking.
No
ONE PERFECTLY MAGICAL WAY
to it!
Any mill-hand walking has used MANY methods to git 'er done.
It's a mill. Go figure they can do more than just the one thing?
T'was ever thus..