Most EDM fluid is a petroleum product. If you don't keep your work submerged, it can and will burn. It won't however carry electricity. Stick your hand in the tank while it's burning. If you wet your pants, change the fluid. :)
=====================
see
Sequel to the Inexpensive EDM, A EDM Gregrich, Arnold Volume
15 Number 6Nov 2002Let the group know what you make.
Unka' George (George McDuffee) .............................. Only in Britain could it be thought a defect to be "too clever by half." The probability is that too many people are too stupid by three-quarters.
John Major (b. 1943), British Conservative politician, prime minister. Quoted in: Observer (London, 7 July 1991).
Back (I think) in the early '70s, Popular Mechanics had an article on a home-built EDM that used household 60Hz and light bulb ballasts to make a simple sinker machine. I built one, and had reasonable luck plunging shallow plastic worm moulds in steel and aluminum with graphite tooling. It wasn't a precise machine, and had no controls except a crank to lower the master and a selection of different bulbs to change current. It ran under kerosene.
LLoyd
============ Sounds like the same machine in the HSM article. I collected all the parts but have never assembled it.
Rather than using the square tube slide HSM described I planned to make an insulating piece to mount a cheap drill chuck and use the Emco mill for actual movements. Did get the insulating piece machined though. Looks like a good way to "drill" hex holes and splines using a spare key of the right size for an electrode.
Anyone using diesel rather than kerosine for dielectric? Diesel is cheaper here.
Unka' George (George McDuffee) .............................. Only in Britain could it be thought a defect to be "too clever by half." The probability is that too many people are too stupid by three-quarters.
John Major (b. 1943), British Conservative politician, prime minister. Quoted in: Observer (London, 7 July 1991).
Stinks worse, too!
If you're gonna fill up the shop with petro-fumes, you might as well make it smell right!
LLoyd
yeah I know, just giving the cons. It is cool to burn holes in hard metal, like I sunk a 1/8 hole through a high speed tool at an angle. But considering all the hassle & expense, not worth it IMOP.
Tony
Yes, the Ram/tank and the power supply sit on a bench.
>
Maybe you can come over and figure out why my ram on occasion jogs the electrode into the table :^)
Tony
If you can power it up, do so. Try to make a cut with a thin (.010 or .020) brass rod, about 2-4 inches long. Use the lowest power setting and the shortest duty cycle you can. Negative polarity. Turn the feed all the way down, the ram should drift up. Set the voltage in the middle, and slowly turn the feed up until the ram comes down and makes contact with the work (submerged, of course). Any hunk of steel will do. It should not deflect the rod. Adjust voltage to achieve 70-80 volts. Now slowly increase the feed, increasing voltage as needed to maintain 70-80 volts. If you can get to about 75% or better of maximum feed without the rod bowing more .005-.010 as it bounces, the valve is in good shape. If you can't get past 50%, it needs to be fixed. 50-75% is okay for slow burning, but for hole popping or fast cutting, you'll probably get a lot of arc-outs, and unreliable cutting.
circuit
intelligent
mending
All expenses paid, and £900 a day I'm yours with a 5 day minimum
AWEM
And fuel oil is cheaper here (diesel has added taxes). We used Shell Diala AX oil for our EDM, back when I was carving carbides. It's probably just a purified kerosene, cost was $5 or $10 a gallon. We rarely needed to change it, but our cuts were generally small (.040 inch hole .200 deep), and our (science lab) projects were generally one-offs.
For tools, we tried graphite, but standardized on tungsten wire. I always wanted to try pencil leads, they should be good for this work.
I don't think so. They're mixed with a clay or polymer binder and conductivity is poor. Making adequate graphite for EDMing is an expensive, time-consuming process.
-- Ed Huntress
PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.