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Machinable Copper bar

I need to make up four 3/4" BSP copper tails (so 1.041" o/d) for the ends of the feed pipes for my induction furnace but my recent experiences machining copper were very mixed, with apparently identical looking bars varying from horrid sticky stuff to nice crisp working almost like brass.

What copper specification should I be asking the supplier for to avoid the sticky stuff bearing in mind that these items carry significant current so need to be highish conductivity , but also need to be mechanically able to take a thread being tightened without stripping? They will be brazed to thick walled copper pipes using Harris Phoson silver / copper / phosphorous rods.

Alternatively if someone has a bar of suitable material of just over an inch diameter and about a foot long then don't be shy, get in touch and I will convert it into pictures of Her Majesty that can conveniently be further converted into your favourite tipple !!!

AWEM

Reply to
Andrew Mawson
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Andrew

Have you thought of trying this with a coventry die head? The chasers can be ground to suit copper, & you might have better luck than with an ordinary die ground for steel. I've got some spare 3/4 BSP chasers which you or I could regrind. I've also got some 2" copper bar which I doubt that I'll use the whole of in my lifetime, but my attempts to machine it have been pretty awful so it's probably not the stuff you're looking for!

Cheers Tim

Dutton Dry-Dock Traditional & Modern canal craft repairs Vintage diesel engine service

Reply to
Tim Leech

stripping?

Phoson

chasers

chasers

Tim,

Thanks for that. Yes I will do it with a diehead - far the easiest option and I have the chasers.

If you have 2" copper bar then at todays prices you can probably retire

AWEM

Reply to
Andrew Mawson

The grade of copper used for EDM electrodes has to machine easily to get a good finish replicated after sparking, so this one would probably be the one to go for. Not sure what the grade would be, but I'm sure that Kevin Steele would know exactly what it is if you paged him.

Peter

Reply to
Peter Neill

Did someone call? Yes, indeed it does machine very nicely, none of the burrs you usually get with copper and it isn't "sticky" either. It's refered to by different people as different things, free cutting copper, telerium copper, "telco", etc.

It's quite expensive, but then so is any copper. the cheapest supplier we've found is a company called RDK (let me know if google doesn't reveal anything and I'll look up the number when I'm at work tomorow).

It is definately worth the extra over normal copper, as it machines like a dream compared to any other grades -we'd never use anything else at work.

Regards Kevin

Reply to
Kevin Steele

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