Building a Pulse EDM machine

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!!
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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.
 
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.
 
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.

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.
 
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.

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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.
 
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.

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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.
 
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.
 
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.
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