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Thread: Has anyone made an EDM/Spark Eroder?

  1. #101
    Join Date
    Dec 2010
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    Finland
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    3,256

    Default

    Quote Originally Posted by PeteF
    Jim, personally I think it's convenient to have all the information in the one place and have a cross-pollination of ideas.

    Thanks for taking the time to find, and then post, your schematics and experience with this.

    Pete
    Ditto on these, keep those pictures etc. in here as this is relevant to the topic in question Helps to have everything in the same place.

  2. #102
    Join Date
    May 2011
    Location
    N.E. Arizona
    Posts
    897

    Smile Back again.

    Hi Everyone,

    OK about keeping everything here, just wanted to ask in case it was getting confusing having to bounce back & forth between pages.

    PeteF: Before I forget again, back in post 38 you asked about the current draw & I mentioned the pump having a ス hp motor. Well, I checked & found it is a シ hp w/5.8 amp FLA draw. So this leaves in the neighborhood of 15 amps for everything else @110V.

    Rich: Back in post 35 you mentioned some cool rotating tips. Thanks for those. At one point I remember someone in the shop suggesting that I should try rotating the spindle. When he mentioned it we had yet to eliminate the transistor failures & once we did, life kept getting in the way.

    I’ve decided that perhaps the best way to go about more details about this EDM is to start pretty close to the beginning. Details keep coming back as I play around w/this again.

    I started this reply last night (5-26-11) & it got too late to finish it – plus I was having trouble as to how to proceed. Then today I found the drawings I originally did in AutoCAD for DOS. The files were last modified 6-2-99. Anyhow, they opened fine w/TurboCAD.

    This is just a photo of the drawing but for those of you familiar w/CAD, you know that once you have a drawing, you have access to any dimension:



    The next photos are of just the main mechanism pretty much as it was used for 95% of the experiments/development. I am showing this so as not to scare off anyone who thinks that you have to build the entire machine just to use it. Most of the holes in the tool bit shown in different views were cut with this assembly propped up over a flat dishpan used to catch the spray.



    For clarity, in the above photo I moved the aluminum collar down to show the bronze bushing that supports the lower end of the ram. This collar is for a shield & came quite a bit later.

    The next photo shows that the end of the ram simply has a standard Parker SS fitting bored on one end for a press fit on the ram. This acts as the collet holder.



    This photo shows the back side & rack that is used to raise & lower the slide assembly. I initially used a cable fastened at the top & bottom of the slide and it was wrapped a few turns around the hand wheel shaft. The vibration of the electrode tapping the work piece was enough to cause slipping and lack of precise control of the slide.


    Continued next post ……………………
    Last edited by jhe.1973; 07-26-2017 at 02:03 AM.
    Best wishes to ya値l.

    Sincerely,

    Jim

    "To invent you need a good imagination and a pile of junk" - Thomas Edison

    "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

  3. #103
    Join Date
    May 2011
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    N.E. Arizona
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    897

    Default Continued ....................

    Found something else too. I had no idea that I still had one of the platinum sample holders that left the impression in the parallel (posted previously @ post 34). This was still in the fixture I made to bend the arms down & it hasn’t been disturbed for over 11 years. You guys are the first to see it. By the way, it wasn’t .003 in thick - it is .005:





    I’m posting another view of the original hole attempts so you don’t have to go back & forth to a previous post:



    This is a composite of top & side clusters to show what I think is important:



    The right view of the 6 somewhat oval holes shows a considerable improvement over the flaring outward of left side holes. This improvement was just from pressurizing the water. So it appeared to me that arc control w/this system is not only electrical but also mechanical in nature.

    Further notice that w/the increase in water pressure a peg started to form in the center from the hole in the electrode.

    I was at this point in the development that my supervisor suggested I contact the person from one of the electronics departments. I ended up partnering with him for the rest of the project and making a great friend for life!

    We heard about a type of EDM machine on campus that was a small, specialized unit for what I can’t remember. This gave us access to a schematic and a starting point for improved electronics. It was while we were discussing this other machine & what I knew of commercial units (wasn’t much) that the EUREKA moment hit me. I felt sure that we needed to keep the voltage low so the point of contact of the electrode would be where the cutting would take place & not the sides.

    Soon after his designing a circuit, we started getting holes like the one in the upper right w/the peg still in it.

    Then came the transistor failures.

    So, guys, What is it that you would like to see next? I still have a fair amount of mechanical details that I can photo & discuss, but so far the discussions (not mine) have been mainly electrical. I can keep going as I am, taking it pretty much as we tweaked it, or jump to just the circuitry.

    Oh gosh, it’s 2:00AM again – no wonder I can’t type w/o a lot of backin gup.

    Those last two words were just as they came out & I got the giggles so I left them ………….. OMG, Not only that, I have no idea of how I just got to italics in my Word Doc.

    Goodnight!!!!!
    Last edited by jhe.1973; 07-26-2017 at 02:09 AM.
    Best wishes to ya値l.

    Sincerely,

    Jim

    "To invent you need a good imagination and a pile of junk" - Thomas Edison

    "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

  4. #104
    PeteF Guest

    Default

    Quote Originally Posted by jhe.1973
    PeteF: Before I forget again, back in post 38 you asked about the current draw & I mentioned the pump having a ス hp motor. Well, I checked & found it is a シ hp w/5.8 amp FLA draw. So this leaves in the neighborhood of 15 amps for everything else @110V.
    Awesome, thanks Jim. When i was asking about the average current draw I was actually thinking abou the current drawn by the spark itself. IIRC you're operating at lower voltages than I'd seen in some other units, hence why I wondered about the current.

    Pete

  5. #105
    Join Date
    May 2011
    Location
    N.E. Arizona
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    Default

    Quote Originally Posted by jhe.1973

    So, guys, What is it that you would like to see next? I still have a fair amount of mechanical details that I can photo & discuss, but so far the discussions (not mine) have been mainly electrical. I can keep going as I am, taking it pretty much as we tweaked it, or jump to just the circuitry.

    Hi Everyone,

    Ok, for me it is easier to keep going w/mechanical stuff as I get this machine cleaned up & ready for whatever comes it’s way. To do the electronics I am thinking of taking the upper & lower units to my friend & spend the day going over them for the component values. Scheduling this may take a bit of time - that & it’s 175 miles each way!

    This first photo shows the SS tray that the table sits in. I just have a scrap piece of plastic in each corner to hold the table up to aid drainage.



    The Rubbermaid container w/blue lid on the right under the table frame is a settling tank for the runoff from the table.

    Next photo shows the coolant system components from the side. By the way, the machine frame is 24 inches square because I wanted it to fit easily through a doorway just in case I need to move it from one shop/lab to another:



    The tray drains into this plastic container about 3 inches below the coolant surface. This is because this tank drains off the surface on the right & I wanted to be sure that metal particles entered below the surface so they would be more likely to settle as the coolant slows & moves across the tank.

    The SS rectangular tank that the plastic tank rests on is the remains of a TIG torch cooler. The motor & pump below is from this unit. The water filter is just a drinking water filter (Kmart/Target/Wal-mart variety).

    You can also see the welder I use now. The frame was built to hold the original welder that was a bit more compact than this one. Now this one just sits on the floor alongside.

    Here I have the set table in place. It is 3/8 thick SS and just rests on the corner pads. The space around it is for the splash shield. The holes are 3/8 - 16 tapped through for clamping & drainage:



    Rear shield in place. Can be any material. I just chose some plastic we had a lot of:



    Continued in next post…………………………….
    Last edited by jhe.1973; 07-26-2017 at 02:20 AM.
    Best wishes to ya値l.

    Sincerely,

    Jim

    "To invent you need a good imagination and a pile of junk" - Thomas Edison

    "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

  6. #106
    Join Date
    May 2011
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    N.E. Arizona
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    897

    Default Continued from above ................

    This shows the front shield in place and the overlap between the two. This has proven to be plenty to keep any spray inside:



    Here is the back of the slide assembly showing the original 6 mounting holes & the 10 holes for adjustment in the column. Disregard the 2 dowel pins. They came later:



    Once the machine was reliable enough to make more permanent improvements, it was obvious that the mounting holes did not provide enough flexibility in height adjustments. I decided to go with a guide along the right side and this is what the dowel pins locate:



    I made the clamps shown and used a piece of 5/8 dia. CRS with the right angle pocket so the screws wouldn’t mar the aluminum column. The column is 2 ス inches square, by the way.



    Continued in next post……………………
    Last edited by jhe.1973; 07-26-2017 at 02:25 AM.
    Best wishes to ya値l.

    Sincerely,

    Jim

    "To invent you need a good imagination and a pile of junk" - Thomas Edison

    "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

  7. #107
    Join Date
    May 2011
    Location
    N.E. Arizona
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    897

    Default Last in this series.......................

    Here is a close up to show how the screws locate into a dimple in the 5/8 rod so that they
    carry the rod up & down as you adjust the slide assembly for height:



    This last shot shows the completed clamp & slide assembly.



    I tried to use SS and aluminum as much as I could for rust prevention. But I was working w/materials on hand so I had to settle for CRS for the flat guide bar & the 5/8 clamp rod.

    When I assemble the slide to the column, I wipe the surfaces w/anti seize compound to prevent the galling that is likely w/aluminum sliding against aluminum. So far, no problems whatsoever.

    For the coolant I use plain water w/automotive anti-rust & pump lubricant additive. I have been using a Prestone product, but today when I hooked up my TIG torch cooler I picked up a similar product from CarQuest and it feels more oily. I might like that better in the EDM, just have to wait & see how it works out.

    Life’s detours keep coming. I have to pull the transmission & transfer case in my Pathfinder to investigate a new noise but I will keep on posting as I can. Just don’t know how this will affect my schedule yet.

    Best wishes to ya’ll.

    Sincerely,

    Jim

    P.S. Last weekend I picked up a digital video camera so I can post a video of this thing working. Of course that is after I go through yet another digital learning curve to figure out how to simply take a video w/o having the camera make my coffee, iron my clothes, nuke my food, answer the phone, etc. AAAARGHHHHHH!!!!!!
    Last edited by jhe.1973; 07-26-2017 at 02:29 AM. Reason: Add P.S.
    Best wishes to ya値l.

    Sincerely,

    Jim

    "To invent you need a good imagination and a pile of junk" - Thomas Edison

    "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

  8. #108
    Join Date
    Jun 2006
    Location
    Austin, Texas
    Posts
    15,631

    Default

    Very impressive work Jim!
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

  9. #109
    Join Date
    Sep 2010
    Location
    Wheaton, Illinois
    Posts
    324

    Default

    Look at machine sales. Elox used to make a good one many years ago. Used an old drill press to hold it.

  10. #110
    Join Date
    May 2011
    Location
    N.E. Arizona
    Posts
    897

    Smile Thank you

    Quote Originally Posted by lazlo
    Very impressive work Jim!

    Hi lazlo,

    Thank you for your comment, but mostly thanks for just letting me know that someone is watching.

    This goes for all of you that have responded to my posts in this thread.

    Not being a speed typist means a bit of time to post/respond. As long as I know that someone is getting something from my efforts I'll keep on going.
    Last edited by jhe.1973; 09-06-2011 at 02:01 AM.
    Best wishes to ya値l.

    Sincerely,

    Jim

    "To invent you need a good imagination and a pile of junk" - Thomas Edison

    "I've always wanted to get a job as a procrastinator but I keep putting off going out to find one so I guess I'll never realize my life's dream. Frustrating!" - Me

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