I am having a strange problem with my MIG welder. the machine is a Miller Challenger 172. I am using only Miller parts in it and have never had any problems, till now.

the contact tip keeps unthreading on it's own, even when I give it a little tweak with pliers. It will work itself out and then I end up melting it because it gets to close to the weld. I normally never put it in with anything other then my fingers before and have never had this problem. It happened with a older tip the first few times, I figured it was just to beat so I replaced it and the problem continues.

any ideas?

sounds like you need a new tip holder. The best place I have found on the net for mig gun parts is here:
http://www.welding-direct.com

Here is my Millers tip holder and tip.

It's actually called a diffuser, not a tip holder. Generally I use some pliers to tighten the contact tip, finger tight leads to loose tips and arcing through the diffuser.

Rene

Originally posted by tRusty
It's actually called a diffuser, not a tip holder.
Rene

I think it's called both!:flipoff2:
http://www.welding-direct.com/2pactipholdi.html

OR

http://www.ramweldingsupply.com/products-view.mcic?s=836

Originally posted by Old Scout


I think it's called both!:flipoff2:
http://www.welding-direct.com/2pactipholdi.html

OR

http://www.ramweldingsupply.com/products-view.mcic?s=836

Don't confuse the issue with facts...:D :flipoff2:

Rene

Thanks guys!

I will replace the....umm.....that piece;) I don;t see what else it could be but the threads in it seem tight and I would think tweaking it with pliers it should stay in there. Plus it never did it before!

seems like the issue would be an expansion and contraction cycle thing. not really a thread or tighness issue.

MJ

I've never had one come loose after snugging it with pliers, not once in 15 years of welding and fabricating for a living.

Rene

time for bigger pliers then:)

That's hilarious OS... ummm you forgot to mention the molecular composition of the valve springs in your sig novel....:flipoff2:

We had that happen in our shop on 2 different welders in the same week. I still to this day believe it was something with the wire as the problem went away and hasnt come back. New diffusers and even a new liner didnt stop it from happening.