graphite electrodes in EDR - use?

OK, I got a couple of bars of solid graphite rems about 3/4" square by 10" long. This stuff feels wimpy to me. I don't want to clamp on the leads from my battery charger. I'm considering drilling and tapping the ends for 1/4-20 brass allthread, and using 2 brass nuts up on the end. Then I'd crimp 1/4" lugs on the ends of a couple of pieces of wire and attach those to my 2 electrodes, then bolt the other ends together using another short piece of brass allthread and 2 nuts, then I'd catch the clamp from the battery charger to that. How do you guys actually attach power to graphite electrodes?


Reply to
Grant Erwin
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Hey Grant,

I don't know what EDR is, as I haven't followed the start of this project. But "attaching power" to carbons used for EDM (not your EDR), they are all attached to some isolatable current carrying platen to which the "cable" is solidly attached, so that there is no need to move the cable at any time. The carbon is then attached to this platen, either though bolted, clamped externally (ie easy to do to with rectangles or rounds), or crazy glued to a special holder for easy change/replacement.

Take care.

Brian Laws>OK, I got a couple of bars of solid graphite rems about 3/4" square by 10" long.

Reply to
Brian Lawson

I'd stick with your idea of drill and bolt, or a bracket that will clamp onto the carbon block. That way you can get nice large wire connections in place that can transfer larger currents without tiny little hot spots that only reduce the power useable. If you don't already have lugs on your cable, clamp a short piece of 1/2 inch diameter copper water pipe straight onto the wire with a vice or an anvil and "FBH". (f______ big hammer!)

It's the cheapest cable clamps you can get and they are almost always available in the junk metal bin. You can drill them to suit almost any screw, bolt or combination of multiple bolts. They are also great for automotive battery or starter connections.

Hope this helps, Peter

Reply to
Bushy Pete

My TLA "EDR" is shorthand for electrolytic derusting. (My TLA "TLA" is shorthand for "three letter acronym".)

Clamping sounds pretty doable.


Brian Laws> Hey Grant,

Reply to
Grant Erwin

Aha. I didn't realize what "EDR" was, either.

I do a lot of the swab-type derusting, with a 1" x 3/4" x 8" slab of Poco 3 I cut off an old EDM electrode. My power supply (a 4-amp battery charger) runs at 2 - 4 amps on this work, and I use a really big bulldog clip to carry power.

I've also used the small battery clamps that come with the charger. Both work perfectly well at 4 A.

-- Ed Huntress

Reply to
Ed Huntress

Grant, I started out fancy by drilling a close-fitting hole in the graphite and inserting a copper wire with the insulation stripped back a bit. Then, I sealed it with glue.

All that is not necessary. Now, I simply allow the electrode to stick out of the solution a half inch, or so, and attach the alligator clip from the power supply.



Reply to
Orrin Iseminger

Ah. That makes sense. I may wind up going that way yet. On another issue, I wonder if there's any way to "soak up" the bubbled off hydrogen. For example, if there were some common household chemical that freely dissolved large amounts of hydrogen, maybe you could soak a rag in it and drape it over the bucket.


Reply to
Grant Erwin

Well, you can use manganese dioxide (it's the black stuff in "dry cells" BTW, for exactly that purpose), but that would be a rather lot more inconvienient than just letting it vent. Platinum catalyst might do it, but you need just as much, only it costs 5000 times more (count on a few pounds of powdered Pt). You got hydrogenophobia or somethin?? It dissipates way faster than is ever flammable y'know.


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Reply to
Tim Williams

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