RE: [CAD_CAM_EDM_DRO] Re: Sherline Spindle Pulse disk for threading

200 lines is 200 pulses per rev. At 3000 RPM (max for most lathes)
that's 50 Revolutions per second or 50 * 200 or 10,000 Hz or one pulse
every 100uS.

If the job of the micro is to accumulate counts from the spindle and
compare against a reference value and then use the difference to change
the spindle speed, you have a nice closed loop motor speed controller.

If you can calculate a new carriage motor speed from that value and also
regulate the lead screw then you have the basic tracking closed loop
system. Engage the half nut when the threading indicator is on a line
and you're good to go. Simple ELS.

But if you want that tool bit to enter the thread at exactly the same
point on each pass cutting 0.002" deeper each time, errors in
positioning while trying to maintain speed become more difficult. Not
impossible. Just difficult and depending on the processor, outside the
time capabilities.

John Dammeyer


Automation Artisans Inc.
http://www.autoartisans.com
Ph. 1 250 544 4950

> -----Original Message-----
> From: CAD_CAM_EDM_DRO@yahoogroups.com
> [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of turbulatordude
> Sent: Friday, November 09, 2007 10:47 AM
> To: CAD_CAM_EDM_DRO@yahoogroups.com
> Subject: [CAD_CAM_EDM_DRO] Re: Sherline Spindle Pulse disk
> for threading
>
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Geert De Pecker
> <geert.de.pecker@...> wrote:
> >
> > Bill,
> >
> > I'm currently playing with the same idea. Not yet done, but you
> can find
> > my intentions here: http://users.skynet.be/gedp/FILES/index.html
> encoder.
> >
> > Optics will come from an old mouse (ir led and phototransistor).
> >
> > Just need to turn some kind of holder. Easy alu piece.
> >
> > Disc will be cut from a cd protector (like you find on blank cd
> spindles
> > to protect the cd's below. Looks like regular cd, but without
> coating).
> >
> > For the marks, I think to print it on transparent en glue this to
> the
> > disc. Maybe will have to darken the stripes with a marker or so.
> >
> > Hope this helps
> >
> > Geert
>
> Hi Geert,
>
> looks like you have a LOT of lines. have you calculated the
> feedback rate and spinle RPM?
>
> I think we did this on the ELS group and software would have a hard
> time keeping up to more than about 6 postions per revolution.
>
> Dave
>
>
>
>
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