Thread: New (to me) Swatys

Originally Posted by tintin

i was told by an old machinist that granite inspection plates were made completely flat by rubbing two together. i guess they cancel out each others imperfections. not sure if it was true or not.

Old masochist here. The plates were made by using three of them and a certain order of lapping the surfaces was required to prevent dishing of doming.
Process developed by Whitworth (England) in the early 19th Century and still a final arbiter of flatness to this day.
Good read...for a machinist:
Surface plates.doc
Any side thrust will put pressure on the opposing side. And a figure 8 or similar motion is used while rotating the plate.
So not all old masochists have all the information. I was taught by a real old timer and can't do 1% of what he could.
~Richard