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Building a Pulse EDM machine

Discussion in 'MARK FRAZIER' started by mark_f, Feb 9, 2017.

  1. NEL957

    NEL957 United States Active User Active Member

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    Mark
    Very nice, love seeing your progress and ingenuity. You are a true craftsman and I love reading all about it, even if I never build one. I will have had the best teacher.
    Thank you.
    Nelson
     
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  2. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    Thank you , Nelson.
     
  3. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    This is the almost completed ram.
    Ram assembly8.jpg I still have to mount the depth stop limit switch on the right side. (you can see the wires sticking out. I also have to make the electrode holder ( I'm still working that out). I works just as it should.
     
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  4. rwm

    rwm Active User H-M Supporter-Premium

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    Very nice! Watching intently!
    R
     
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  5. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    Thank you.
     
  6. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    I got an email with a reply but it isn't showing here. The email mentions losing the thumb screw on the DRO. Actually I tapped it out and put a bigger thumb screw. The thumb screw is needed. This is a depth stop. Once the electrode is in place, you put the switch on the ram in "setup" and move the DRO to trip the depth switch by watching the depth LED. Then zero the DRO and move it to set the depth to burn. Then lock the thumb screw so it can't move. When the ram reaches the depth, it trips a limit switch and stops the burn.
     
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  7. frugalguido

    frugalguido United States Iron Registered Member

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    I really like your build, first class all the way! When your done it will look and work like a commercial purchased unit.
     
  8. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    The photo here is the "depth stop switch" Shows the switch mounted for the depth stop. I mounted a third limit switch in series with the down limit switch. (the diode across the down limit switch goes across both switches).
    depth stop switch.jpg


    This photo "Plastic Work Tank" is my new plastic work tank. I got it from U.S. Plastics. It is 16" W X 12" D X 8" H with 1/4" wall and bottom thickness. It is made of polypropylene. I chose this because it will stand up to EDM fluid and also kerosene.
    plastic work tank.jpg


    The next photo "ram and control is the two units as is right now. The ram is almost finished.
    ram and control.jpg


    The next photo "ram assembly 8" is the ram assembly to date. The only thing left to do is the electrode holder. I am still working on the design for it. I an leaning towards a bronze holder mounted in a nylon block. it will be similar to what Ben describes for electrode orientation and will have through the tool flushing.
    Ram assembly8.jpg


    The photo "ram cover" is the cover I had engraved to match the control panel.
    RAM COVER rendition.jpg

    The last photo is the bulkhead fitting for the work tank drain. It is made of PVC with a Viton seal. It has threads for 3/4" pipe fittings.
    work tank drain fitting.jpg

    I chose this machine to build for its quality. I also chose to order everything new (instead of scrounging for parts) and order the parts list provided by Ben Fleming. My reason was to see what the cost would be to build Ben's machine as he designed it. My conclusion so far is that even buying everything new, this machine is a bargain. At this point I have About $600 invested plus $150 worth of custom engraved panels. These were for looks and not a necessity. The total cost with the rest of the materials will about $1000 including $125 for 5 gallons of EDM fluid.


    I searched machines to buy (new and used) and a machine of this caliber runs $5,000 to $10,000, therefore, in my opinion making Ben's machine a bargain.
     
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  9. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    I got most of the electrode holder made today.
    electrode holder 2.jpg The brass fitting is pressed into the nylon block. I still need to drill and tap for a set screw to hold the electrodes.

    electrode holder 3.jpg

    electrode holder.jpg The top is tapped for 1/4" NPT. I will install a plastic push connector here to attach through the tool flushing.
     
  10. DAT510

    DAT510 United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Hi Mark, Great Build!

    Out of curiosity.... How will you be centering the electrode on the Part? Will the Ram assembly be mounted to a X-Y slide assembly?

    Best,

    Chris
     
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  11. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    The work tank will mount on an X Y table (from Grizzly) to move the tank into position. The ram will mount on a column behind the tank so it can be adjusted up and down.
     
  12. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    The oil filter for the flushing circuit will mount on the side of the tank. A clamp plate holds it securely in place. ( I ain't drilling no holes except for the drain in this $113 tank!)
    Filter.jpg Filter2.jpg
     
  13. JohnnyTK

    JohnnyTK Canada So New Still Setting Up Shop! H-M Supporter-Premium

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    Mark what a great build, cannot wait to see this in action.
     
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  14. FOMOGO

    FOMOGO Puerto Rico Active User H-M Supporter-Premium

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    Really nice work on the EDM Mark, and I agree, for $1000 it's a bargain. Looking forward to the trial runs. Mike
     
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  15. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    I drilled a hole .125" off center for an electrode alignment pin. All electrodes and holders will have a .125 pin through the center to go against this pin. this is so an electrode can be removed for repair or replacement and put back in the exact same position. I make make several .500" shafts with a .125 pin for making electrodes.
    alignment pin.jpg
    Every electrode will mount to a .500" shaft that goes in this chuck. The shaft can be drilled to accept an electrode or one can be soldered to the shaft. There will be a few shafts with a fixture on the end to clamp or hold electrodes. One will look like a miniature machinist vise. another will have a square slot with set screws to hold square electrodes. There will be a third one that has a miniature V block on the end to hold round, square or other shaped electrodes.
     
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  16. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    While waiting for parts to finish building the framework for my EDM machine, I got to thinking. I hate it when I build a machine and can't use it because I need to make tooling for it. So, I decided I better start making tool holders for this machine. I looked on the internet and found some I liked and want to make. This one was available to by for the tidy some of $300. WOW!!
    FullSizeRender - Copy (4).jpg

    FullSizeRender - Copy (6).jpg

    FullSizeRender - Copy (3).jpg

    I made it for free from scraps in my shop. I made several shafts from .500" diameter drill rod, drilled them for a .125" dowel pin. I can mount different ends on these shafts for different electrodes. This one will have two 8-32 thumb screws put in the empty holes. This holder will hold round, hex, or square electrodes making it pretty universal. You can see in the last photo, the reason for the alignment pin. Every tool holder shank will have the same pin through it. This allows an electrode to be removed for repair or replacement and re-installed back in the exact previous location. This is similar to the commercial system called " system 3R. They are terribly expensive to buy, so I will be making them.
     
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  17. ghostdncr

    ghostdncr United States Active Member Active Member

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    I'm really enjoying this build, Mark! Yes, 3R makes some incredible tooling and while their stuff is also incredibly pricey, scour their offerings for ideas. Many sound tool holding ideas can be gleaned from what they offer. The V-block example you posted above is an old favorite of mine that I borrowed from 3R twenty-plus years ago, cutting mine onto one of their standard 20mm machinable holders. Another version I used extensively also used one of the machinable holders with half the diameter ground away about 30mm up from the bottom to leave a flat surface. an 8-32 hole was tapped about halfway up this flat and above and below were set 1/8" dowel pins on offset centers. I used this holder for most any blade or rib-type electrode up to around 4" in width and found it to be extremely repeatable. Pretty sure I've still got both holders and can post pics if you'd like.
     
  18. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    That would be great.

    I saw that holder with the half flat and two pins while surfing the net for ideas. I don't remember where now and when I saw it, I had no idea what it was for. Guess I should look for it again.

    Another I like is a tiny tool makers vise fastened to the end of a shank. The vise is 2" long , 1" wide and jaw depth is .400". jaw opened to 11/16". The commercial version is almost $1000. I found a vise for $30 and will make one.
     
  19. ghostdncr

    ghostdncr United States Active Member Active Member

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    Here is a photo of the modified 3R tooling I mentioned yesterday, Mark. From right to left, the first two are identical on the business end with the offset dowels for positioning blade electrodes. You'll notice the shank ends are different, with one being round for the standard 3R 20mm holder and the other being ground square. The square-shank tool was used with a 3R ram fixture that looked somewhat like an angle plate and had clamp screws to press an electrode down into the notch of the angle. One of our EDM's was fitted with this base so I ground up this holder for use on that particular machine.

    Third from the right just has a drilled and reamed hole for holding a copper tube. We had one high-volume job running almost constantly that involved many 1/2" holes tapped into an Inconel casting. Taps frequently broke off in this material and I kept this holder loaded and ready to go at all times for clearing the broken taps and saving the very expensive castings.

    Fourth from the right is my little V-block holder, which works splendidly to hold any size round or square electrode that will fit into it.

    The aluminum "arm" on the far left fits onto either of the two blade holders on the far right. I made this for some job I only vaguely remember, but it involved burning a blind slot up inside a bore of approximately six inches ID. It worked out very well, but any error made in setting the ram's upper stop limit would've gotten rather loud and expensive, I'm thinking.
     

    Attached Files:

  20. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    Thank you for the photo. That blade holder looks like the 3R one I saw on the net. I guess you make the blade and drill the pin and bolt holes in it. The pins keep it from moving.

    I plan on making several more of the shanks with the pin in them just to have around to make any needed electrode holders.
     
  21. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    There is a 100 CFM fan inside the cabinet blowing OUT over the power resisters. I installed a second fan on the outside of the inlet vent blowing IN. This gives a better circulation through the cabinet.

    FullSizeRender - Copy (7).jpg FullSizeRender - Copy (8).jpg IMG_0598.JPG IMG_0596.JPG
    The local Radio Shack near me is going out of business and right now everything left is 90 % off. I got two of these $26 fans for $3 each. I have a second PC board for this machine and I bought most of the components and controls to build another EDM control box. I have spare parts or if someone decides to build one of these I can save them a few hundred dollars.
     
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  22. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    I started to lay out the flushing system. There will be two available flush nozzles to provide flushing for the cut. The brass fitting will supply fluid for through the electrode flushing. I am going to make one change here. The right end of the piping is going to turn down into the tank and have a ball valve. This will be the pressure regulator for flushing. Fully closed will give full pressure of about 6 to 9 PSI. By opening the valve a little , the pressure can be reduced , bypassing excess into the tank. I can not plumb the inlet yet until I get the pump I will use. A lot of folks put the filter and pump in the end of the tank. It is less messy to change filters that way, but I want all the space I can for the work area. I will just put a small pan under the filter to change it.
    flushing.jpg This is system is only for flushing. There will be another pump in the storage tank to fill the work tank and continuously circulate the fluid through the work tank, another set of filters, and back to the storage tank.
     
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  23. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    This part of the design is a work in progress. I am kind of figuring it out as I go from what other people have done. I know what pump I want to use, so I am plumbing for it.
    flushing2.jpg
     
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  24. JimDawson

    JimDawson Global Moderator Staff Member Director

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    Mark, that panel looks great, very professional. :encourage:
     
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  25. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    Thank you , Jim. I am proud of this build. It is the most complex and costly ( but still a bargain) build I have done to date. I am anxious to test run it.
     
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  26. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    I removed all the PVC plumbing and replaced it with copper pipe. The PVC was too bulky and I didn't like the way it fit. The copper is a much better fit and I like it better. (You have this when you design by the seat of your pants)
    flushing3.JPG
     
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  27. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    I have been working on the plumbing schematic for my machine. I want to keep it as simple as possible, but still have all the features I want. The storage tank and filter will be under the bench the machine will sit on. The containers for the felt bag filters are insanely expensive, so I devised an inexpensive design. My filter will be made from a 2 foot length of 6" diameter PVC pipe. I have all the pieces on order and the cost will be about $50 instead of $400.
    machine plumbing schematic.jpg
    I found a Little Giant magnetic drive pump brand new on eBay for less than half the price they sell for. It will pump the fluid. There are a lot of parts on order , coming next week.
     
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  28. NEL957

    NEL957 United States Active User Active Member

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    Mark
    Does it require all that filtering, I understand the flush must be clean but that clean? I wish you mentioned the second filter because I have some of the filter from the processor that are brand new. I put them up thinking I would use them some time, wrong. Too many pipe dreams.
    Looks real nice and can not wait to see it working.
    Nelson
     
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  29. NEL957

    NEL957 United States Active User Active Member

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  30. mark_f

    mark_f Global Moderator Staff Member H-M Supporter-Premium

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    Actually yes. Mr. Fleming said that good filtration will make a bad edm machine look good. Bad filtration will make a good edm machine look bad. I remember how dirty the oil gets real fast. It requires really good flushing at the cut and really good filtration to get a good burn. You can not over do the filtration. I will be using a 5 1/2" diameter X 21" long felt filter bag rated at 20 microns to filter the oil and the spin on filter is only filtering the flushing. These bag filter housings are insanely priced from $400 to $1000 in the size I desire. Sooooo ..... I will build mine. I have everything to build the housing. I am looking for perforated steel or aluminum sheet metal to make the filter basket that holds the filter bag in the housing. Depending on bag life, I may go to 10 micron filter.

    The home depot filter is not big enough. I would be changing filters constantly. Also those elements are not the best for the oil.
     

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