On Fri, 05 Mar 2004 17:34:18 -0400, you wrote:
Better tracking of the spindle speed changes that may occur. The
variations depend on the machine, the spindle and quite a few factors, so
for some there is an advantage, for others there is none.
Art - I know that my setup with a big DC motor and VFD is "lumpy"
below about 350rpm, (with my mid range belt setting) when timed over
short periods but is stable when timed over a long sample time. It's
the nature of the beast <G>.
Am I going to get any advantage fitting this multi slot sensor?
I can easily change belt ratios and get smooth spindle speeds at
100rpm with the motor doing 1000rpm.
Currently I'm running 1:1 ratio, the 500-1000rpm range works great, I
can turn, thread, face, bore just about anything that fits in the
lathe and take up to .5mm cuts in steel without any barfs if I get the
feedrate right.
The EMF feedback in the VFD works pretty good, really abusing the
lathe looses no more than 50rpm (at 700), but it takes some tweaking
to get it not to over/under compensate and it changes somewhat
depending on the stock material.
I don't let it do that sort of thing normally, 200mm/min and .25mm
roughing cuts in Aluminium suits me, I drop the feed to 100mm/min for
steel - slow but steady, and I'm still using last years inserts <G>.
--
Steve Blackmore
