unstable arc

[the black box]

hi

ive recently brought a swp 160c mig welder and im am using murex 5kg 0.6mm wire and 5% co2 argon mix. i cant maintain a stable arc at all it sounds like a machine gun which would suggest that the wire speedis too fast but ive triedall speeds and all voltages tried swapping the wires over inside but made little difference. my gas is set to around 10lpm- 20lpm and im getting soot around the splatter and on the contact tip but i can hear and feel the gas coming out. i tried using it on the house mains direct with no difference. the wire occasionally binds on the contact tip when it hot but realese when it cools slightly. im really at a loss ive tried everything and am starting to come to the conclusion that it is faulty. i have done an ok ish weld with it but it was very difficult and normally the weld seems to sit on the surface. do you think it could be that ive got to have a 16a supply ive blown the fuse once on number 5 out of 6. would really appreciate any help on this as im at a loss

cheers
rob

ps im currently learning at college and have been doing tee, butt, and lap with great success and has past acid etch examination and bend tests will get pics later of one of my butt welds and the splatters that this is currently producing.

 

[Tigman]

Have you got a good earth ? What thickness you welding , is it clean metal !

 

[WindWalker]

Is it a brand new machine or bought second hand?

What size steel are you trying to weld? Saying you've blown a fuse already on number 5 I assume it must be 3mm plus? Have you tried it on the lower settings on thinner material?

If second hand it may be worth servicing the torch with a new liner (for .6/.8 wire) and a new tip. Is the feed roller set to the right groove for .6 wire? Worth checking the gas diffuser in the torch as well and make sure the shroud is clean.

Not sure what wires you mean when you say you have changed them over inside. The torch polarity?

As Tigman says, check for good earth and make sure metal is clean.

 

[NotANormalCoder]

Can you confirm model details - SWP do a 170C and a Varmig 1600 (plus some newer models that I've tested but don't know the release numbers for). Both these models have gas/no gas capability, so check you have polarity correct - Negative earth, Positive torch.
If it's set up correctly, release wire drive tension and check that motor speed varies with turning speed pot. If it doesn't, it sounds like failed pcb - If poss, return to dealer under warranty. SWP are quite good and will normally collect/return FOC if it's their problem. If it's second hand, this is probably why the last owner got shot of it, but fixing it shouldn't be expensive.
Dave

 

[the black box]

thanks for the replies it is the swp 170c mig welder. i now definately have a negative earth and positive torch. im currently trying on 6mm, 2mm and 0.8mm all with the same results. it is a brand new machine as for the earth i am connecting the clamp directly to the work piece and it seems a good secure connection i am cleaning the metal where im welding but not where the earth is should i be doing this.

 

[Tigman]

If it's painted yes and if it's really rusty yes again !

 

[the black box]

this might be the route of the problem as it is not completely rusty but does have surface rust and one pannel is painted on one side. so i will clean the metal down completly and try again

 

[Tigman]

Hope it works for you , I'm not familiar with your machine but don't give up , try all the settings and adjust the wire feed from slow to fast as you go , just needs fine tuning by the sound of it !

 

[the black box]

excellent thanks for your help definately will not give up on it i have a 79 fiat 126 to restore and other projects will get some pics up soon of some of my welds

 

[Tigman]

Good easier to diagnose too!