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good desigh for homebrew edm?

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  • good desigh for homebrew edm?

    Electronics is not my thing so I would like some advice on plans for a homebuilt edm. Anyone build one from the book sold on this web page? My intended use would run toward broken tap and screw removal, no production.
    Thanks
    hms50
    hms

  • #2
    Langolis' Build an EDM is the best explanation I've seen so far. The book has all the info for a complete "system", power supply, feed, & mechanics. As an electrical engineer, I found little to improve upon electrically. Mechanically I used materials from the junk box, but my junk box may have been somewhat better equipped than Langolis'.
    Wes
    Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
    ~Practitioner of the Electromechanical Arts~

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    • #3
      Apppears Village press has stopped printing this one, got the below via google: Note spelling is "Langlois"


      TITLE: Build an EDM Electrical Discharge Machining, Removing Metal by Spark Erosion
      by Contribution by: Joe D. Rice, Robert P. Langlois, Clover McKinley
      ISBN: 0941653528
      Publisher: Village Press Publications
      Publish Date: 01/01/1997
      Binding: Hardcover
      List Price: USD 39.00



      Store Book Price Shipping Charge Sales Tax Total Cost in USD Order Processing Time Shipping Time Click
      to Buy Save the Info
      Powell's 18.00 3.50 0 21.50
      1 copies available

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      • #4
        Go back to the opening page of this BBS and select "Store". Under Books, Shop Projects, is Robert Langlois' "Build an EDM" for $18.00. 8 1/2" x 11" Softcover.

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        • #5
          This one has been on my back burner since the artical came out. I'm having a hell of a time finding capacitors in the right voltage and Mf also transformers.
          I'd appreciate any help especially any dumpster diving sources as my funds are limited.
          Thanks guys.

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          • #6
            Rustybolt:
            try 1-800-digi-key or www.digikey.com or www.digikey.ca


            [This message has been edited by Thrud (edited 12-17-2002).]

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            • #7
              For transformers and capacitors:
              C and H Sales
              PO Box 5356
              Pasadena, CA 91117
              (800)325-9456
              www.candhsales.com

              For transformers:
              Surplus Center
              PO Box 82209
              Lincoln, NE 68501-2209
              (800)488-3407

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              • #8
                RE scrounged parts, ......they can work, but in general, parts made for the purpose are always better.

                Electronics isn't that different from machining, parts are like tools.

                The capacitors take a beating, being charged fast and discharged like a photoflash. The construction is diffrernt for high ripple current parts, and even more so for arc discharge parts.

                The others will work, maybe for years, maybe for minutes.

                I would save bux on the less important parts........

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                • #9
                  Thanks for the info guys,
                  I've ordered the book and will give it a good read. An EDM would be a great addition to any shop and at least in the photo it seems like it would fit in most!
                  Have a wonderful holiday season!
                  hms50
                  hms

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                  • #10
                    Thanks from me as well.
                    Mery Christmas everyone!

                    Comment


                    • #11
                      Thanks for the info Sprocket. Book is on order as of 30 seconds ago.
                      I figure I owe Village Press a Christmas Gift as well as my self.

                      Especially Merry Chrismas to Neil and Villagepress. They been giving all year long to me.
                      Steve

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                      • #12
                        I built one of these as noted in a previous post. One change I made was to use a 1 kva 220/480 volt primary, 120 volt secondary machine tool control transformer. I connected the primary, configured for 220 volts to the 120 volt line. This yielded 60 volts on the secondary, perfect for the application. Machine tool transformers are heavy but rugged. The 1 kva (kilo X volt X amp, I don't know why they don't rate these things in Watts, volts X amps =Watts)is somewhat of an overkill, but I wouldn't go less than 750 va.
                        Also, I purchased new capacitors rather than having an old one die on me at an inconvenient moment. As others have suggested, I paralleled smaller capacitors to get the values I needed.
                        Wes
                        Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                        ~Practitioner of the Electromechanical Arts~

                        Comment


                        • #13
                          wes: one question, one comment.
                          Question: is it your feeling that the 60 volts ac output is better than a higher voltage? what makes you think so? Is that two questions?

                          Comment: Transformers are rated in volt amps (or Kilo volt amps) because volts times amps does not equal watts when a capacitor or inductor is in the circuit. in theory, you can be drawing the maximum amps and volts and be producing zero watts. Look at the "pole pig" out side your house and you will see it is rated in KVA. It tied up to power factor. It is also why you cant measure the load on an inducton motor by looking at the amps it is drawing.

                          another question: have you played with different values of capacitors? what is affected if you do?
                          Steve

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                          • #14
                            The available energy per spark is affected by the capacitor and the voltage.
                            Directly with cap value, and by the voltage squared. So about 80 volts would produce double the energy of 60 volts.

                            This isn't always what you want. The more spark energy, the more the hole is oversized from the electrode.

                            BTW, paralleling smaller capacitors is a really good idea, because the ratings for current tend to drop off slower than the value. Thus a bunch of smaller parts are good for more ripple current than a few larger parts of same type.....so they last longer.

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                            • #15
                              <font face="Verdana, Arial" size="2">Originally posted by Oso:
                              The available energy per spark is affected by the capacitor and the voltage.
                              Directly with cap value, and by the voltage squared. So about 80 volts would produce double the energy of 60 volts.

                              This isn't always what you want. The more spark energy, the more the hole is oversized from the electrode.

                              BTW, paralleling smaller capacitors is a really good idea, because the ratings for current tend to drop off slower than the value. Thus a bunch of smaller parts are good for more ripple current than a few larger parts of same type.....so they last longer.
                              </font>
                              Are you saying for example;instaed of one 2000mf capacitor you could use 4 500mf capacitors of the same voltage rating?
                              How would you wire that up?
                              (Keep in mind unless it has to do with wiring up a motor I'm a complete cretin.)

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