[78-L] VARIABLE MICROGRADE 78

[Michael Biel]

From: Kristjan Saag <saag at telia.com>
> The Variable Micrograde method, patented by Deutsche Grammophon in
> 1946, had nothing to do with variable pitch. It was the cutting
> speed that was varied, producing variable distance between grooves.

There are Language problems here.  In Technical English, "Variable
Pitch" DOES mean variation in the distance between the grooving with
changes in lines-per-inch. "Cutting Speed" as you use it in this
circumstance would mean the variation in the rotational speed of the
feedscrew moving the cutter head forward.  When it turns faster the
grooving gets spaced wider apart, slower moves them closer together.  In
all instances the rotational speed of the DISC remains constant!!  Both
terms are leading towards the same result. 

Mike Biel  mbiel at mbiel.com