Re: [CAD_CAM_EDM_DRO] Re: Wire EDM

> --- In CAD_CAM_EDM_DRO@y..., "turbulatordude" <davemucha@j...> wrote:
> > Gotta love Google
> >
> > did a Google search for "Jon Elson EDM"
> >
> > and got this url
> > http://www.artsci.wustl.edu/~jmelson/edm.html
> >
> > pretty cool huh ?
> >
> > My question is.... can you use an ARC welding machine ?
> > seems the power is there. I just don't know about the power
> > regulation.

Sure, if you want to weld! The trick to the RC scheme I used is very limited
energy. Just enough to vaporize a tiny speck of metal. The commercial
EDM systems use very fast electronic switches to turn off the current after a
very short time (microseconds) of arc. This blasts away a lot more material
per minute, because the electronic switch can reset a lot faster than the RC
circuit charges the capacitor.

> > It also seems that there is a reaction zone as the electrode
> > approaches the part the flow begins to increase until metal starts to
> > move. then as the proximity of the electrode and part increase,
> > there is a point where there is a small enough gap that the arc jumps
> > with no restriction and a short circuit is created. then you need to
> > pull back and start again.

That's how a tap disintegrator works, but it is a pretty rough process.
Controlled approach and retract would take days to remove .1" of metal.
The RC scheme combined with rotation of the electrode works pretty
well for making round holes. What you want is a steady infeed of .001"
every 10 seconds or so, with the RC zapping at at least 100 times a second.

>
> >
> >
> >
> >Well I would not use an arc welder.....
> You should use an adjustable pulse generator...
> Mine varies from 5Khz to 52Khz......
> and my pulse width is adjustable from 750ns to 2.25us
> the width is the on time....
> the generator sends this out to an hp2601 opto,
> which in turn is applied to current amplifiers via switching logic...
> switching logic is used to enable 22 parallel current amplifiers,
> which is switching -200vdc when in open gap....
> more info is available...
> John Elson rig is crude but effective

VERY CRUDE! Yes, I admit it! I was just fooling around with the
process when I needed to burn out some broken taps. I intend to
build a pulse generator some time, but EDM is not a process I'd use
very often.

I don't think I'll need as much current as your system, however!

Jon