EDM

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Ive done business with these folks before. They will often take significantly less if the item doesnt sell on Ebay.

Shrug

Ask for Yavone

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Reply to
Gunner Asch
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I ran D10s for a few years, very accurate EDM machines with sensitive heads. Less than 1% electrode wear can it do! At the company I EDM-d fine blanking tools in production, to close tolerances. Julius

Reply to
Protagonist

What type of finish does one get with EDM? Any pcitures on the web? Is this something that the average guy could have in his shop? Any bizarre requirements?

Peter

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Reply to
Peter Grey

That particular one, a Charmilles D10, will give you a very nice, random finish -- maybe something like 8 microinches Ra in steel, to take a guess.

Of finishes? Maybe. Try Mitsubishi, Charmilles, Agie, Sodick websites. You might also try Google Scholar and look for an engineering article on something like "EDM surface finish," without the quotes. There have been lots of photomicrographs published over the years.

It's possible. Some people do it. You need a good reason, though, IMO.

Don't tell your house insurer. He'll run screaming as he tears your policy to shreds. They do catch on fire if you get a little loose with your shop hygiene. They also catch on fire sometimes, anyway. And don't put one in a basement shop. Your whole house will stink of hydrocarbon fumes.

Don't consider running any dielectric fluid except the best grades of commercial stuff, with flash suppressants and so on. Invest in a heat-triggered fire-extinguisher bottle (they're sold on the EDM aftermarket). Resolve not to leave the thing running untended. Really. And then buy another fire extinguisher.

EDM is great stuff. It's no more dangerous than the character running it, which is to say, you have to understand the machine and how many kinds of foolish mistakes can cause a fire. There are quite a few. But a D10 would be a hell of a nice home-shop machine for someone who uses his head and who takes the time to learn before throwing the switch.

It's a specialized tool that gives you extraordinary geometric machining capability in exchange for *very* slow metal removal rates, messiness, and some fire risk.

Their primary use in commercial work is in making injection molds and other production tools. Before putting your money down, though, read about the process so you know what you're getting into.

-- Ed Huntress

Reply to
Ed Huntress

I've had an EDM in my home shop for several years. Its great for that stuff you can't do any other way. Inside splines, square holes, burn taps, simple molds (pour in resin). I only use it three or four times a year and I've never gotten proficient at it. Run it good enoough to just burn something is simple; good enough for an injection mold with great surface finish and little electrode wear is quite another.

Karl

Reply to
Karl Townsend

SNIP>

Not sure what you mean by "shop hygiene", but poorly filtered dirty EDM fluid does seem more prone, but maybe that's because the currents are higher?

Commercial EDM oils don't instantly "catch fire", but rather start with little puffs of wispy flames of hot vapours bubbling up in a flooded tank operation, or surface flames-ups for a few seconds in surface flooding burns. Left long enough, there will be a fire, but not instantly. That's why most EDM's have a "flame sensor" in the safety circuit, providing some bozo hasn't jumped it out or turned it to face away from the work area.

Kerosene is a greater real hazard, and it "stinks".

Water as a dielectric won't catch fire, but doesn't carry heat and swarf as well either.

Take care.

Brian Lawson, Bothwell, Ontario.

Reply to
Brian Lawson

I don't know what, specifically, makes dirty dielectric more prone to fires. But I was talking more about spills and films of dielectric oil on the machine. They spread the fire quickly.

Two caveats: First, most EDM fires appear to start when the work is NOT properly flooded and submerged -- something that neophytes are prone to do. Second, a lot of small-time EDMers have used kerosene for EDM fluid, and some probably still do. Someone who doesn't know the story, told that kerosene is an effective EDM dielectric (it is), might be inclined to try it. It also makes a great fire starter and a fast ride to burning your shop down.

Here's something a European EDM sales exec once told me, that I'll never forget. He was in charge of his company's business in developing countries in Asia. "I never have trouble finding the EDM shops in a city in that part of the world," he told me. "Just before the plane lands, I look for the columns of smoke..."

They may have a completely fireproof oil-based EDM dielectric now (I have no idea), but the ones I have experience with were flame *retardant*, and not flameproof. They're hard to get started but they will burn.

The commercial dielectrics doubtless have improved since I was involved in EDM, but we used the best stuff that money could buy. Running our machines 'round the clock, the kerosene or related smell built up, despite the deodorizing and odor-masking stuff they put in it.

Well, actually it does conduct heat much better than oil. But you need a power supply designed for it, and it has its limitations in sinker-type EDM work. I doubt if you could run a D10 with water...at least, for very long.

-- Ed Huntress

Reply to
Ed Huntress

Thanks for the info. I don't think this is something I'll jump on, but the thread is interesting.

Peter

Reply to
Peter Grey

With the right EDM fluid, polished, mirror finish. Great advantage for molds for polishing time and ease. Also, EDM don't care about material hardness. Some times though materials, like titanium, carbide can be EDM-d with great ease, vs. conventional machining. I bored 1/16" (+/-.001")holes through 1" thick Titanium in 1-2 hours, using cooper-tungsten electrode. I have over 10 years experience with EDM sinkers.

Julius

Reply to
Protagonist

Not with that machine you won't.

I've got a hurco edm with computer controlled orbiting head I'd get rid of if anybody is interested.

Reply to
Dave Lyon

The ones with the optional power supply would do a nice job ( about 12 Ra) but compared to todays technology you wouldn't be able to afford the time. Fully configured, a D-10 had three seperate power supplies in a single cabinet as well as a little "add on" box that had to be plugged in.

When these machines came out, they were the cats ass. They would make a great home machine today and they might be good for someone with little need for EDM but compared to the latest and greatest they are an electromechanical Rube Goldberg device.

I would not, however, want to have to get one fixed. Repair parts probably cost more than the used machine would and you'll have one hell of a time finding a service technician that knows what's up.

Reply to
John R. Carroll

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The seller of this EDM states: "This system appears to be in fair to good cosmetic condition but has not yet been tested." No statement they intend to do so.

In straight language I think this means "As is". This means they have no firm idea (at least no guarentee) this machine will work. This, of course, is not uncommon.

Since you seem to know something about these folks do you feel they would take the machine back if it should prove too expensive to refurbish? Or perhaps offer to compensate after a certain amount of money has been spent? Or would they allow testing "on-site"? Most folks would rather not get left "holding the bag" any more than the machinery dealer would.

dennis in nca

Reply to
rigger

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You should also check to see that the 380V Main Power transformer is included. They were delivered both with and without this. If it has the transformer from the MTB it will be easy to spot as it's part of the machine if I recall correctly. It's been a while since I saw one of these.

Reply to
John R. Carroll

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Its a fair amount of money..so give her a call and ask. It cant hurt a thing.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Reply to
Gunner Asch

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That's a clean little machine Mark. In 1978 this was the state of the art in sinker EDM power suply technology.

If it is 100 percent it's worth the asking price but if it needs any work at all it's not worth much more than a grand or 1,500.00 at the most. The transformer, BTW, is in the lower part of the magnetics cabinet and the little box on top of it is the microfinishing power supply/servo control set up.

It looks like a 10 Amp (current to the electrode) supply with both high (180) and low (90) voltage. That means you can do "no wear" roughing. It could be 25 amps but I can't tell from the photo's. You have to be careful with these machines if you do because they will actually build material on the electrode if you aren't careful when you run no wear. When that happens you end up with some really nasty DC arcs. Big, deep, nasty holes blown in your part.

The flush unit also has both pressure and suction which is very handy. It takes suction to get the best finishes because your spark gap is usually nearly zero. The gage on the tank is the gage for both.

These things usually have a base that everything but the pumps and tank are mounted to/on. I dont see that in the pictures. You could bench mount the thing pretty easily though. This would definitely be something cool to have for gun porting and other home shop applications.

Reply to
John R. Carroll

That's true, for Charmills, very difficult to get service and expensive. We had to get guys from Chicago to fly out. Even than some young guy showed up with a voltmeter, no experience, spending lot of time on the phone how to fix the thing. Julius

Reply to
Protagonist

Ed and whoever else wants to chime in,

I'm starting in to make an edm, following this guy's approach:

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is really a well thought out book and a nice simple edm design for the home shop. Not like I have a specific task in mind for it, but it looks like a fun project.

I have been a bit concerned about the fluid. Since I'm an electroniker, I have to ask--what kind of power supply works best with water? If you can, give me the electrical particulars; timing, dutycycle, voltage etc.

Thanks, Steve

Reply to
Steve Smith

That machine looks like a great project, Steve. One or two other people who have stopped in here were building those things. I'll be really interested in how they work.

As for water dielectric, you'll need to get an update from somebody else. As with many things, my info is historical and fading fast.

Here's some 20-year-old info: Water dielectric allows fast cutting but it's hell on electrodes. As of today (20 years ago ), it was restricted to wirecut and to fast hole eroding, with wire-like electrodes that you plunge with a lot of flushing. The water has to be deionized, although there have been a variety of snake-oil additives that supposedly speed cutting and which allow a lot of current flow.

I don't recall how wire EDM or hole-poppers were set up in terms of power supply parameters. That's stuff I've long since forgotten. IIRC, the machine you're working on is an RC relaxer circuit. If you want to try water, there are only a few things you can adjust, so I'd just have at it.

Wirecut is a lot older than many people realize, BTW. Andrews Engineering had a wirecut attachment back around 1958 or '59. Charmilles may have had one earlier, and I know that Elox was working on it at least by 1960.

Agie put the pieces together with CNC and made the whole thing practical, around 1971 or so.

Excuse me for going off on an historical tangent...

-- Ed Huntress

Reply to
Ed Huntress

I have an older Hansvedt EDM, its very safe to use in a home shop,, but it may not be practical for most. I don't have any odors, or fires.

With the tank and all the equipment they take up alot of room. They are expensive to maintain. (If you need to replace the EDM fluid expect to spend about $800 for a fluid change for the good stuff.) The hydraulic systems can be expensive to repair. The dielectic pump is a special design, positive displacement that can handle abrasive particles in the stream.

They require alot of tweaking, lots of knobs to turn. Also, the finish can be less than expectations. I had to make my electrode holders. And drilling graphite electodes to provide proper flushing makes me cringe when I get the dust on my lathe. Have had some workpieces damaged due to arcing. Also, my machine has a quirk of jogging the electrode into the work once in awhile.

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Reply to
Tony

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Synthetic EDM fluid is available from Germany, green colored. Expect to pay 3x the price of regular fluid. Some one brought a sample once from a tool show, but my company never got into it. Julius

Reply to
Protagonist

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