On 3/26/2025 8:41 PM, Bob La Londe wrote:
I've got a book around here somewhere on making a simple EDM sinker for burning out broken taps and bolts, but from what I understand the
electrode is eaten up as is the material. So far I haven't broken off a
tap in something I couldn't recover that was so precious as to be worth
a day or 3 making such a contraption. Well, not since i bought the book anyway.
Those type machines typically use a copper rod or copper tube.
It is my understanding that complex difficult to machine parts (square
inside corners) are sometimes made by EDM using a machined graphite electrode. How quickly is that electrode eroded? Does it erode.
Somewhere bouncing around in my head I have some misconglomeration of thoughts telling me I might have heard or read about using graphite
electrode EDM for making mold cavities. Now I have no intention of
starting an EDM shop, but I am curious about the process. I often have customers send me jobs (most I turn or explain away) that want sharp
inside corners in a mold cavity. A lot of them I can explain that if
they can live with a tiny radius I can do it, but if it has to be sharp
I can't, because or course its never for something with a flat bottom
that I can broach.
I'm not sure I even have a grasp on what questions to ask. When I turn somebody away I like to be able to suggest to them where to look for
somebody who can solve their problem.
I have seen some amazing videos of sinkers, and wire EDM, but I'm not
sure I've seen anything do what I am thinking of. Sinking a positive
into a piece of stock and getting a matching cavity.
George Bulliss, the admin at The Home Shop Machinist forums, has a great
reply to my query in post number 5.
https://bbs.homeshopmachinist.net/forum/general/2115731-edm-mold-making
--
Bob La Londe
CNC Molds N Stuff
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