On 2008-01-11, wrote:
I just bought a used welder which is larger than my old one. The
seller only sold the welder, not his cables. The cables on my old
welder are fine, and are supposedly made for all welders. At least
that is what I thought. For some reason the plug on the Ground Cable
on this new welder is thicker than the Hot one, so the standard cable
plugs fall right out.

I suspect that is intended to reduce the chances of accidentally
interchanging the ground and the hot. Is this a fancier machine with
switches to change the polarity at need? Or an AC machine, where it
does not matter what polarity is used?

Yesterday I stopped at our local farm supply
store. They carry a good selection of welding items, and they did
have the thicker plug. I was just going to change it, when I
discovered that I can not figure out how to remove the old plug. I
dont want to break it, because I may want to use my old welder in the
future again.

Did you bother to buy the plug, or did you leave it in the
store? Examining the new plug might give you clues as to how the old
one is fitted.

The cable end has a molded kind of material that is shaped like a
piece of plastic pipe about 3/4" thick and 3" long. There is no set
screw in it, no hole in the side of it, and it does not seem to be
screwed on. Tapping on it does not seem to slide it back. How the
heck do these things come off? I'm guessing there's a set screw under
that molded "pipe" insulator, to take the wire out of the brass plug,
but first I need to get that insulator off and I have no clue how.

Anyone have any idea????

Well ... I've seen lots of high current connectors, and the
possibilities a

1) Wire soldered or crimped into connector, and the plastic sleeve
molded on.

2) Wire soldered or crimped into connector, and the plastic sleeve
screwed onto the connector body. Grip the pin, and turn the
sleeve counter-clockwise (viewed from the cable end). (Check
whether the sleeve has a smaller minimum diameter at the cable
end than at the pin end. If otherwise, then it may unscrew from
the pin end instead, so you rotate it the other way.

3) Wire soldered into connector with a two-part sleeve screwed
around an increased diameter part of the pin.

4) (2) or (3) above -- but with the setscrew which you expect
(which I think less likely for the kind of current which you
need to carry.

Note that I have seen some connectors with covers like (3) above
which were two-part in the metal, too. The pin is female
threaded in the back, and there is a sleeve which slides on over
the wire and which is then soldered in place. The sleeve has a
matching male thread, so it is screwed into the pin after the
soldering is complete, and then the two halves of the sleeve are
screwed together over that. (Obviously, the cable end of the
plastic sleeve has to be slid onto the wire before the pin is
screwed in place -- and (depending on sizes) perhaps before the
metal sleeve is soldered to the wire.

5) One of the many other possible ones.

If you need to keep the cable so it can go back into the old
welder's connector as well, I would suggest that you buy the male
connector to fit your new welder, a short (perhaps one foot) length of
cable, and a female connector to fit the connector on your old cable, so
you have adapted it to the new welder.

I note that you have cross-posted this, but I don't see signs of
what I would have considered the best newsgroup for the purpose, SEJW
(sci.engineering.joining.welding). They certainly have experience with
the connectors used in welders.

I've not read that newsgroup, as I do not have (yet) a welder,
though I have lots of experience with various styles of connectors,
including some high-current ones.

Good Luck,
DoN.

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