Re: [CAD_CAM_EDM_DRO] Re: EDM part examples from DIY machines? (sink and wire)

I have an ancient 'electron drill' sinker (about 1947). If anybody
has a wiring diagram, I would appreciate it, it has a meter missing
which doesn't seem to affect its operation. I only use it to
remove pins used to hold VW roller bearning crankshafts
together. I use hollow metallic tubes which I think have
tungsten in them. Copper is also available. Due to the
erosion of both the pin and the tube, I get a tapered hole.
Carbon blocks are also used as a 'bit'.
Since there has to be a space for the making and breaking of
the arc, the hole will be bigger than the bit. Since the bit is not
rotating, it is possible to get more erosion on one side, but this
is largely corrected by the fact that it is a tube and not solid.
I have thought about having the 'bit' not only vibrate, but rotate. \
As it is, if the tube/'bit' gets too ragged at the end, I just grind it
off to true it up and continue. The Tube/'bit' is consumable and
it depends on what you are cutting and the make up of the 'bit'
is. I picked the machine up from the scrap bin (there were two
of them) and rebuilt it (mostly just cleaned it up) and tried different
'bits' . There are several suppliers for the sinker material. I had
not used the machine for sometime and forgot what the cutting
fluid was. I ordered some from a EDM supplier who sold me
fluid for a wire machine. I thought it was rather expensive.
It was also almost explosive when used in a sinker machine.
I use water soluable oil and water for a cutting fluid. Someone
may want to comment on that. The electron drill has an automatic
feed which works quite well, but I don't understand why. It has no
electronic control, it is just a dc motor that interprets the voltage
current in the arc circuit. It has a rheostat to fine tune the speed.
I hope this has helped, and maybe it will elicit some more coments.
bob mcknight



To: CAD_CAM_EDM_DRO@yahoogroups.com
From: "turbulatordude" <dave_mucha@...>
Date sent: Mon, 17 Oct 2005 21:48:12 -0000
Subject: [CAD_CAM_EDM_DRO] Re: EDM part
examples from DIY machines? (sink and wire)
Send reply to: CAD_CAM_EDM_DRO@yahoogroups.com

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--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Mike Mueller"
<mueller914@y...> wrote:

>
> I just recieved 2 plans for building a wire-EDM and a sinker-EDM.
>
> I was wondering if anyone had picture examples of parts made/modified
> with such a machine.
>
> What kind of tolerance could one achieve? For the sinker, if I had
> a .25" diameter electrode, will it make a .25" hole or will it be
> larger or ???
>
> Sorry for the silly questions...
>

The electrode will cut a hole that is about 0.003" larger than the
electrode.








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