Re: [CAD_CAM_EDM_DRO] PC ports, Encoder resolution and EDM PSU info

Jon;
some time ago in the Model engineering workshop magazine was a project about a edm machine, and for what I can remember it used
stepper motors for lifting the electrode up and down,everything was described, power supply ,mechanics,and even the pcb was
available.
regards
mariano


Jon Elson wrote:

>
> dave engvall wrote:
>
> > > Tim Goldstein wrote:
> > >
> > > > played with EDM by hooking up a 48 V 10 amp transformer through a
> >
> > > > bank of power resistors and then a cap.
> >
> > It is my understanding that one really needs a base voltage of about
> > 28-32 V at reasonable amperage plus a spike of approx 90 V to
> > breakdown the dielectric.
> > I've done a little fooling around but after modeling the process using
> > the POCO CD am convinced that one need a good supply with
> > var. pulse freq.
> > If anyone has plans for a supply I'd give it a try. I have a handful
> > of 15 A igbt to try on something.
>
> I made a mini-EDM system for burining out taps, etc. I did a couple
> broken taps
> using about 30 VDC, a 30 Ohm resistor and about 3 uF of capacitor right
> across
> the EDm electrodes. There might be a small spike from the inductance in
> the wire,
> but the behavior I saw was an arc that repeated about 50 - 100 Hz. So,
> I believe
> the cap drains energy into the arc, the arc is suppressed by the EDM
> fluid, the
> resistor charges the cap back to near the raw DC supply voltage, and
> then the
> EDM fluid breaks down and a new arc forms.
>
> There were no semiconductor switches at all, and it worked quite well.
> Now, you
> might be able to get stable cutting on a much wider electrode, or faster
> cutting
> with electronic switching of the arc, but it is not necessary to make
> the process
> work. This may well be necessary for wire EDM, to prevent welding the
> wire
> to the work, or just burning it away.
>
> Jon
>
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