From: none@none.com99   
      
   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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