Ok, went to BOC this morning and traded in my Pureshield Argon for a cylinder of argoshield light.

It's eliminated all the spitting and the welds are much cleaner, but I'm still getting the occasional problem of the wire melting back into the torch.

I'm thinking now that it must be a wire feed problem, if I just sqeeze the trigger the wire feeds slowly, but if i really squeeze it hard then the wire feeds much more quickly. Is it meant to do this or have I got a faulty trigger?

you don't say what MIG welder you have.

can't say I'm an expert but it may be possible that on some models the wire feed speed is dependent on the trigger pressure but I somehow doubt it.

Take the torch apart - 2 screws - and insdie there will be a springy piece of copper that makes contact agasint a brass block - the gas vavle - wel, at least on the Clarke MIG I have it is like that.

Clean both contacts with fine wet'n;dry and try again.

If it continues to do that, take a look at the motor, especially if it is an old Clarke model.

I posted about this a month or so ago.

Had similar symptomto yours excpet in my case the wire would either feed or not and seemed to be related to how I pressed the trigger.

Sounds like a faulty trigger, it is just an on off switch. What size wire are you using and have you got the feed roller the right way round, there should be two different size grooves in it and if you are using the wrong one it will affect the feed.

I expect the feed motor is low voltage DC, and thus will be much more affected by any resistance in the switch contacts than a mains ac motor

I agree with the others, you need to inspect/sort out the switch

John

Thanks guys, it's a SIP handymig, and inside the torch is how 02gf74 describes. I'll take it apart and clean it up tomorrow.

I'm using 0.8mm wire btw.

if its an sip then it will be wire feed.

if you look on www.mig-welding.co.uk there are some good mods you do to improve it.

sip's are very well known for suffering from wire feed problems.