Re: [CAD_CAM_EDM_DRO] Orbiting Ram Edm

Hi Jared:
If you have a simple orbiter (rather than a CNC EDM that can run
spherical orbits) you have to distort the 'trode as you suggest to
accommodate the orbit plus the overburn in X and Y, but only the overburn in
Z.
For basically 2D parts it's not too bad, but it can be a real killer on 3D
parts with goofy surfaces that have to be geometrically accurate (shutoffs
in plastic molds are a good example).
I do all my design in Solidworks and jigger the shapes to accommodate the
'trode geometry as a separate configuration of the part.
I then just bring it into Masterscam and cut as if it was a conventional
milled part.
That way I avoid the distortions in Z that accrue from faking the cutter
diameter on surface milled shapes.
(tip comping an undersize ballcutter is a not- too- bad fake on shallow
surfaces, but it will screw you up good on steeper surfaces if they have to
be accurate)
It's WAY easier to pony up the cash for a CNC EDM that will do spherical,
but I don't get enough moldwork to justify having one, so I fake it.
(I also farm out any EDM work that's out of my equipment's league)
For this class of work, there ain't no shortcuts (not yet, anyway)
Cheers

Marcus
PS: the newest version of Masterscam is supposed to have an electrode
programming utility...I'll believe it when I see it!!

----- Original Message -----
From: "J" <jaredts@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Monday, September 30, 2002 6:36 PM
Subject: [CAD_CAM_EDM_DRO] Orbiting Ram Edm


>
> I machine graphite electrodes for orbiting ram edm machines using cnc
machining centers. Anyone have experience compensating for the orbiting of
the electrode? The electrode has to be smaller in the x-y plane but not in
z to orbit out to the correct size. The only methods I know of are
physically modeling the electrode smaller or using a bull nose endmill and
lying about the diameter. Seems like some software should exist to
compensate. I am currently using Mastercam for toolpaths.
>
> Jared