Re: emc for wire edm control

[celgo-at-eject.co.za]

----- Original Message -----
From: "Dave Engvall" <dengvall-at-charter.net>
To: "Multiple recipients of list" <emc-at-nist.gov>
Sent: Thursday, March 13, 2003 7:25 PM
Subject: Re: emc for wire edm control


>
> Michael,
> Oh, Ouch! If an '8' can do it then it doesn't take much processor power.
> That is 12 bit code done in octal. Not too many instructions.
> I might still have a book on an 8 around here someplace.
> PDP/16 code is pretty straight forward.
>
> Dave Engvall
>
> On 3/13/03 8:43 AM, "Michael Coffey" <mdynac-at-prodigy.net> wrote:
>
> >
> > Ray Henry wrote:
> >>
> >> Marcel
> >>
> >> I have done a bit of work here and with Roland Friestad planning for
such a
> >> retrofit.  He has a two axis Agie wire EDM that is a few years beyond
factory
> >> service.
> >>
> >> We had planned to use an analog signal for wire current but your
approach
> >> also sounds interesting.  This could simply be a voltage up signal
> >> optocoupled to a parport pin and read by tkio.
> >>
> >> One way to achieve the reverse path is to simply record the positions
of each
> >> axis for each motion loop.  This is how we ran the first backplotter.
The
> >> second plotter does the math to make a vector from a whole series of
points.
> >>
> >> With a file like this, when the parport pin goes low/high the grapical
> >> interface could abort the running program, switch to mdi mode, and
issues
> >> each point back in the recorded position file as a g0.  Repeat this
until the
> >> pin clears.  Once cleared, we could restart the cut at the activeline
when
> >> the short happened unless we crossed position into a previous block of
code.
> >> If that happened we would need to decrement the activeline by 1 and
restart
> >> there.
> >>
> >> Cutter comp may cause a few problems but a few tests with the
backplotter
> >> should show a good approach here as well.
> >>
> >> Ray
> >>
> >>
> >> On Wednesday 12 March 2003 12:18 pm, Marcel wrote:
> >>
> >>> Hi
> >>> I want to know if its possible to change emc to control a two axis
wire edm
> >>> machine. A wire edm machine need to be able to go back when the
cutting
> >>> voltage is low (shorted) and only start to go back to the cutting
direction
> >>> when voltage is high Regards
> >>> Marcel Gombault
> >>>
> >>> This email was scanned by the ICL anti-virus solution.
> >>
> >>
> >>
> > Not all Wire EDM's "back up" during a shorted condition.
> > For example, most Japax wires go into feedhold during short,
> > and then continues along the contour after the short is cleared,
> > usually by flushing,
> > Sensing the voltage at the gap is the best way to achieve this.
> > A simple, yet precision comparator/opto circuit works nicely here.
> > Setting the circuit to output at, say 20 gap volts, is a good starting
> > point. Then tweak it for best performance...
> > In my opinion I would get the machine up and burning using this
> > approach, then delve into the more complex task of actually making the
> > machine backup in a shorted condition.
> >
> >
> > I am currently working on a retrofit for wire/sinking/hole popping EDM's
> > Both servos and steppers.....
> >
> > I have several old 2-axis "blue" Andrew 330's and 630's with servos,
> > these macines do backup during short, a DEC PDP8\a is the heart of the
> > axis motion on this beauty.
> > Does anyone know how to dis-assemble pdp8\a a code???
> >
> > and an old Japax 4-axis machine with steppers, this machine feedholds
> > during short
> >
> > Hope this helps....
> > Michael
> >
> >
> >Hi Michael
 I  would like more information regarding the sinking/ hole popping as I am
currently bussy with components for cnc applicationd
(http://web.eject.co.za/celgo/
>
>
> This email was scanned by the ICL anti-virus solution.
>
>

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