graphite electrodes in EDR - use?

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.

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

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

Clamping sounds pretty doable.

Grant

Brian Laws> Hey Grant,

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

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.

Regards,

Orrin

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.

Grant

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.

Tim

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