Mig torch liner

Should be able to pinch the wire with 2 fingers just after the feed rolls, and have the wire slip. That's about all the tension you need. Particularly so with fluxcored wire, which is essentially a metal foil with flux inside, like a sherbert straw.

As for the liner arcing out... I've seen it a few times, but it's not super common. Most times the operator uses the torch like a hammer, and the insulators at the nozzle or torch neck are FUBAR. Liner welds itself to the torch neck or euro block, and it's goodnight Irene.

I'll put up some pics tonight, if i feed the wire out of the torch liner it feeds ok so i feel the issue is in the liner or torch handle area.

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Originally Posted by loanrangie

I'll put up some pics tonight, if i feed the wire out of the torch liner it feeds ok so i feel the issue is in the liner or torch handle area.

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I replaced my liner, eventually to find it was the pinch rollers instead.

One roller is mounted firmly.

The other roller is on a plastic backing, secured in place by three screws, which had slipped over time - undid the three screws and pushed the plastic mounted roller back toward the other roller and re-tighten the screws.

Liners can kink. Especially the coiled steel type. Remove liner, run fingers along it to check for kinks. Get kinky with it [tonguewink]
Most manufacturers don't reinvent the wheel with their liners. So basic rule of thumb for this kind of thing is to supply the torch model if known, otherwise ID the torch, or give the machine model if the torch is a standard fit to that model. Then you'll likely either get a tweco or binzel liner of the right wire dia and torch length.

Feed issues- Check liner, rollers, then correct contact tip size.
I actually knew a bloke who swore by running oxy tip cleaners thru his mig tips... don't be that guy. Not only does it chew the inside bore of the C/tip up, but it creates swarf which exacerbates the problem of a clogged liner. If you haven't yet, give that darn torch a birthday and give it some new consumables, or better still, get a new torch if the machine is holding together well.

Just to be sure, HOW do you know it's a feed issue? What symptoms are you seeing, or what measure are you using?
Simple stuttering / juddering of the wire feed while welding of the weld could be volts too low, or even intermittant loss of the circuit if you've got an intermittant issue somewhere else... Could be the feed motor control board a dodgy burnback function (if applicable) or a number of other things...

Mitch, we were taught to take the tips out to clean them, then blow them out. I totally get why you wouldn't do it whist still connected,, but off the unit? Mind you, we only did this a few times before replacing anyway due to increasing the orifice size.
Yeah/nay?

Nay.
Contact Tips are a consumable item. You could, but you probably shouldn't mess with them. You might get away in a pinch, but not a viable option long term. In a workplace, the boss would be crazy to be paying his employees to down-tools and dick about cleaning a tip while fabrication grinds to a halt over the cleaning of a 60 cent part.
Tips can get covered in spatter, but you've usually got bigger problems by this stage, and probably should have considered investing in some anti-spatter spray or nozzle dip well before this point in your mig welding life. There are some new generation ceramic based anti-spatter sprays which by all accounts are the bee's knees. Will vastly increase consumable life.


The basic contact tips are a copper alloy. They are also the only point in the gun where the voltage is transferred to the mig wire (which then does the 'welding' bit). They also get darn hot. So eventually the copper anneals, gets soft, and the smooth bore of the tip wears (ovalises) and the wire no longer feeds correctly. In extreme cases, the wire could momentarily lose electrical contact with the tip, you get micro-arcing etc.. all bad news.
MIG wire, as part of its production has a cast and helix (like a memory), so the wire feeds not straight thru the tip, but spirals. This is the mechanism thru which the tip wears.