Re: USB and ncPOD system

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Lester Caine <lsces@...> wrote:

> My thought had been - what happens when you turn the spindle
> by hand. Impossible with a single pulse, but given a high res
> encoder you would get the tool moving back and forth as you
> rock the chuck given the ideal interface hardware :)
> Mach3 can't do that, and I doubt EMC2 could ( unless you can
> leave it IN a screw cutting pass), but all the calculations
> say that it is quite practical.

Funny you should mention that. At last years CNC workshop, Chris
Radek (one of the EMC developers) had a Sherline lathe with a
spindle encoder, and was demonstrating threading. He turned off
the spindle power during a threading pass, and as the spindle
slowed to a stop, so did the tool. He then turned the spindle
manually and the tool followed it.

Single pulse per rev for threading would only work if your
spindle drivetrain is robust enough that the speed doesn't
change during a threading pass. For light cuts on a heavy
machine that's easy. Heavy cuts on a light machine, not so
easy. Using a real medium to high resolution encoder lets the
tool track speed changes as they occcur, not just once per
revolution.

Regards,

John Kasunich