Building a Pulse EDM machine

Mark_f

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I am back and starting a new project. I am building an EDM machine. I often thought it would be nice to have a version of an Electrical Discharge machine to burn out a broken tap or drill.I did a little research and found there are many "spark eroders" and EDM machines out there that are home built. My research showed me that a decent EDM machine may be worth the investment. Back in the early 80's, I set up and ran a large industrial EDM machine and know what they are capable of doing. In my research, I ran across a couple of books by Ben Fleming on building an EDM. He also has a yahoo group dedicated to building and using an EDM.
While his simpler machine would make an excellent "tap burner" and be a lot less expensive to build, I have opted to build the pulse machine as it is higher quality and more versatile.
So ....... get your popcorn and hang on.

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Welcome back - will be following.
 
The first thing was to get a design. Ben wrote a very good book covering the building of his version of an EDM machine. I ordered the book for around $30. I was impressed when it came. It is not a pamphlet.... it is a real high quality book. He also offers a printed circuit board as an option to make construction easier.

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I opted to by the printed circuit board at an additional cost of about $55.
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This board came with a 9 pages of instructions including a complete parts list and very good instructions for building this control board. Also the list contains a source and all part numbers to order.
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The board instructions are very concise and step by step with instructions for testing. Ben has done an excellent job on this and has made it so almost anyone can build this.
I went online and ordered all the components to build the pulse control. The cost was about $290. With the electronics and transformers the cost to build this machine will be about $450. I feel this is reasonable considering a comparable machine commercially would cost several thousand dollars. I have materials on hand in in my scrap box to build the actual machine.
The electronics parts are supposed to arrive tomorrow.
 
This ball bearing drawer slide wil be cut down to 10 to 12 inches long. In the plans and most builds I have seen, this was cut fairly short and uses 4 of the ball bearings on each side. I intend to leave al 24 balls on each side. I picked through the slides at the store until I found one that was tight and smooth. By leaving it longer, I feel it will have better stability.
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The drawer slide will hold the ram assembly and let the servo motor move it as needed to keep the spark gap constant.
 
As I scrounge for needed parts to keep from buying everything, a friend gave me a new aquarium pump to use for a dielectric pump. It has a capacity of 400 gal / hour. This should be plenty strong enough for the purpose. It is a magnetic drive so there are no seals to leak and it is submersible should I choose to go that route.
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It has 1/2" inlet and outlet.
 
YES Welcome Back. Looks like a fun project. At the present time, I don't need one, but I'm sure as I follow your progress, I will absolutely
NEED to make one.
;)
CHuck the grumpy old guy
 
I've wanted one for some time and knowing how you are soooo good at what you build I'll be watching and trying to build one from your findings.Guess this is the push I've needed. Yes Welcome back !!
 
Although the machine can be built in a less expensive version, I have opted to build the more expensive version. If you only want a tap burner, it would suffice to build Ben Fleming's RC version machine. However, I always want to go for better. This pulse machine will be much more versatile and has the ability to to more intricate work with better finishes.
I used the parts list from Ben and ordered ALL the control parts new from the suggested supplier. Scrounging old electronics devices such as televisions and computers, I probably could save some money but this was mush easier and I have all the correct and new parts. The electronics order came to $317 including shipping. I also ordered the three transformers at a cost of $157 including shipping.
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This pile of bags is the close to 100 components to stuff the PC bord and build the complete control for the EDM machine.

Following the book, I listed all the controls for the machine and made a layout for the front panel.
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This is a drawing of the panel with switch and control knob locations. Yhe two large boxes in the center represent the meters for volts and amps.

The following drawing is the one that will go to the engraver.
EDM FRONT PANEL5.jpg
The panel will be lasered onto an aluminum panel that is anodized black and the lines, numbers, and letters will be silver. This fancy panel comes at a price of $100 but will make a very professional looking machine. It will look "store bought" :grin:. I expect the final price of this machine to be around $600. I saved a lot of money scrounging for the materials to build the actual machine part. $475 of the cost is buying all the electronics new, which I felt was worth the time saved and the ease of building, but a good scrounger can cut this cost in half. While this sounds expensive, I looked at New comparable machines and they run close to $10,000.
 
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