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hitachi230
17th Jul 2007, 10:16 PM
Hello all
The earth clamp on my Lincoln 225amp welder needs renewing. Browsing the WIA online catalogue I see there is such a thing as a magnetic earth clamp (only I suppose there's no clamp as such, just a piece of magnetic steel) Anyone had any experience with one of these? How long do they last? I thought heat and magnets didn't get on?

Thanks for any help.

Bernie

Wood Butcher
17th Jul 2007, 10:28 PM
I have used one once and had no problems with it, but it was no where near where I was welding so would not have gotten hot. Heat and magnets do not get on. Once a magnet reaches a certain temperature (called the Curie temperature I think) it looses its magnetic properties.

Personally I don't think I would buy one. I prefer the standard spring type clamp but get the ones with brass contacts not aluminium.

DJ’s Timber
17th Jul 2007, 10:29 PM
I had one of these and they are a pain, the spring that keeps the pin pressed against the steel loses its temper and the magnet collects all the little filings and spatter making it hard to get a good contact unless you clean it every 5 mins

Grahame Collins
17th Jul 2007, 10:39 PM
Hi Bernie,
The reason that an earth clamp will get hot is that the connection is poor. Resistance across the poor connection causes the heat build up.

If your magnet earth clamp is attached to a clean surface it will not get hot.

It is poor mechanical (bolted ) connections and spatter rust and other crap under the clamp to surface interface that causes the grief.

Mind you I am not recommending the magnetic clamp.They can be a pain in the rrs. Every bit of stray bit of ferrous material will find its way to the magnet. If you have weld using a DC current near the clamp they can cause arc blow as well.

There is better ways to spend the $30 or so that they charge for the things.



Cheers
Grahame

specialist
18th Jul 2007, 07:15 PM
Probably the best one that I have seen and used is an old G clamp with a hole drilled in the back to hold the lead. They clamp on, no springs to lose tension, and if the fittings are kept tight, never fail.

My 2 cents worth

specialist