Re: stepper edm

Dave

i get the idea that by electrolysis you mean secondary erosion or some other feature that slows the work or robs power.>
something that increases with depth
I think you're seeing the difficulty in evacuating the dirt.
As the cut gets deeper, the dirt has to escape upwards thru a narrow area between the wall and the tool.
Yes, orbiting helps this, and in this bottom cutting scenario, does not significantly reduce cutting area
( Say the circle area is reduced by a few thou on the diameter.)
But a thread is often done with orbitng but in a different way.
Bore a hole with drill (chip machine) or tube electrode (edm)
Make the correct threads on a smaller dia tool that will fir inside this bore,
move the tool in towards the bottom of the bore and orbit the threads laterally into the wall..
Do not rotate the tool, just orbit it.

Regarding the slowness of the cut as it progressed,
hole drilling edms are like gun-drilling,
very high pressure flushing, often hundreds of PSI thru a .010" or less hole
results in a fairly good flow of dielectric thru this tiney chimney we spoke of.
No manufacturer orbits this forming operation.
Everyone flushes the !$#! out if it.
For hobby EDM use a 'paint pot' .
put oil into a spray painting vessel and put air pressure into it, hook the output to the tool.

> 1b. Re: stepper edm
> Posted by: "turbulatordude" dave_mucha@... turbulatordude
> Date: Wed Aug 9, 2006 8:37 am (PDT)
>
> --- In CAD_CAM_EDM_DRO@yahoogroups.com, Thomas J Powderly <tomp-
> tag@...> wrote:
> >
> > Graham,
> > IMO the advantage of orbiting is simplification of electrode
> manufacture.
> > IMO orbiting is NOT faster/b
> > etter than plunging.
>
> Tom,
>
> on my home-brew edm, it took me approx 15 min to drill the first 1/8"
> of a tap.
> the next 1/8" took close to an hour.
> to plunge to a depth of 1/2" took over 6 hours.
>
> As the electrode progressed the
> electrolosys increased geometrically.
>
> spinning the electrode with a bent wire a-la Jon Elson's page
> eleminates almost all of the electrolosys. orbiting would also work
> wonderers.
>

Yes far is safe, if the bore is big enuf, use a plate tool on end of a stem.
or dip a smaller tube in flyback transformer paint (fly dope) to make sure it doesnt cut

> The magical key is that the electrode has to be as far from a wall as
> possible. and that only the cutting edge can be near the work.
>

'better than', very true, but not good.
make an ice cube in plastic tumbler
let it melt a bit so it's smaller, fill the void with water.
try to pour in milk and see the effectiveness of orbiting.
pull the ice up once while pouring milk and see the effectiveness of a single jump
done

But take a deep rib that extends over the edge of a part & I'll just pee on it
Without the tank full!
The surface tension DRAWS the dirt outta the cut.
The dirt doesnt have to fight thru the oil top get out.
If the rib is fully enclosed in stock, it's a whole 'nother ball game
but your mental picture will show you what you can do.

> In the home brew machine, orbiting would allow one to pee on the
> outside with fluid and get much better flushing than with a non-
> orbiting.
>

it all depends on your resources& jump is cheap
orbting is good, but is not always the best solution
a good mental image of waht happens is very valuable

> I cannot speak for the professinal machines, but a rotating or
> orbiting electrode on the home-brew can shave hours off a hole.
>
> Dave

TomP