[78-L] runout spirals

[Michael Shoshani]

On Fri, 2010-10-08 at 08:53 -0700, DAVID BURNHAM wrote:

> There are two possibilities - either the recording 
> stylus, after the music is finished, is activated by a cam to go through the 
> eccentric groove motion to create the trip groove, and then moved ahead a 
> millimetre or so and so activated again, or, the recording stylus disengages and 
> a separate cutter, mounted on the same assembly is brought down to engrave the 
> trip eccentric.  

I'm thinking the separate machine theory as well, but here's the kink in
the works: the eccentric grooves on VEs are different sizes. If the dead
wax is larger, the eccentric pair is really large, but if the dead wax
is small, the eccentric pair shrinks. If they used a cam on one of their
machines, it would have to be adjustable in some way.

Early Capitols and I believe some early Deccas are cut with an eccentric
runout spiral. This would indicate shifting the wax or lacquer disc
somewhat while the spiral and locked groove were being cut, I think...

MS