Re: [CAD_CAM_EDM_DRO] Auto tool changers

Hi Drew,

OK, I saw the slots, and I now see three holes on the circumference, Are
these the ones? Yes, three photo interrupters could give a direct
readout of the positions. the "edge" encoder I mentioned was to be used
as an index. The PIC can "find" the index on startup, and keep track
of the 6 positions. I understand that ENCO already has this type of
encoder setup on the spindle (I think I've got one coming!).

Bill tells me that the turret "drops back" into the detent, so I'm
guessing that a "ratchet" effect is in play here, and one would only
have to insure enough steps to get a little past the next detent
position, and then allow the mechanism to drop back.

I suspect that the original DC motor was just shut off, and the detent
took over, therefore, the stepper implementation should do the same.

Instead of a PIC, a Cybernetic Microsystems CY545 stepper controller
could be "programmed" to the the job. A little more costly then a PIC,
'tho. (I've just been talking to them again).

Interesting project! I wish there was a (simple) way to "model" the
mechanism, so that the driver/code could be worked on. The worm gear
data would have to be known, and other details of the mechanism, or the
actual hardware.

Alan KM6VV


Drew Rogge wrote:

>
> The six positions consist of three slots and three holes.
>
> It might be more interesting to do somekind of BCD encoding
> or something which would allow the PIC to know what position
> the turret is currently in. That way you wouldn't have to
> always start the turret in the same position when the PIC
> powers up. Or I guess you could have somekind of a home switch
> the PIC could read.
>
> I'm curious how one would prevent the stepper from continously
> pushing back on the "stop" too hard and/or for too long.
>
> Drew
>
> Alan Marconett KM6VV wrote:
> >
> > Hi Bill,
> >
> > Perhaps if a simple encoder disk is added to the turret. 6 slots (one
> > to the edge), would allow two photo interrupter sw's to report the
> > position of the turret. A PIC could then drive a stepper (even a simple
> > unipolar driver), and do the "rotate past, drop back to lock" sequence
> > that you've said is required to change the tools. I have a Sears/EMCO
> > 5" lathe (no CNC... yet), would this fit on my lathe? How much? I'd be
> > interested in a swap of some kind to get a mechanism to work with (kinda
> > putting the cart before the CNC horse!).
> >
> > It only looks like three tool positions in the pix?
> >
> > Alan KM6VV
> >
> > wanliker@... wrote:
> > >
> > > In a message dated 2/21/2002 11:09:26 PM Mountain Standard Time,
> > > johnhe-uk@... writes:
> > >
> > > > I'm thinking of three of four
> > > > tools. I've looked but not found any prices on the internet
> > >
> > > If you go to the following URL, there are pictures of the guts of an EMCO
> > > COMPACT 5 CNC/PC TURRET.
> > >
> > > http://www.grifftek.com/c5cnc/c5cnc.html
> > >
>
> --
> Drew Rogge
> drew@...