Mig Wire Spool Tangle

[JohnAspinall]

I'm wondering if anyone can figure out what the problem here is. Nearing the end of a 2lb spool of 0.030" steel wire in my (Miller 211) welder, and the wire is hanging up on the spool. A closer look shows that the loop of wire that is one turn away from coming off the spool has trapped the outgoing wire underneath it. Pic should make it clearer.

When I clear the problem, it happens again a few turns later.

At first I thought this was too little tension on the spool, letting it unwind too much and creating loose loops. But cranking the tension up didn't do much. I also backed off the tension, which didn't do much either until the whole spool was starting to unwind which was clearly bad.

So, suggestions?

 

[Ken_Shea]

John,
No familiar with the Miller 211, does it have a feed tension on the wire it'self or just on the spool of wire?
Seems that it may be hanging up as it goes through the liner creating a small loop then feed continues but now wire tightens on the crossed loop. Presume the tip is clean.

 

[JimDawson]

Normally I would say that's a tension issue, but you have already addressed that. If possible have somebody watch it while you're welding, or just stand there feed wire until it fails again and see what is causing it.

 

[Franko]

I looks like there is an overlap that's made a knot. If that's the case, you'd need to pull the spool off the spindle or pull the wire out of the liner and drive wheels to untie it. I can't think of a way a knot could be made while the spool was rolled, but it could have happend if you took the spool off recently and and somehow the tag end was threaded under a loop when you reinstalled it.

 

[JohnAspinall]

Good questions:

I looks like there is an overlap that's made a knot. ...

It's like a slip knot, where the outgoing wire tucks under the next loop, then comes out again the same side. I've had the spool off completely to make sure the wire started out wound properly.

No familiar with the Miller 211, does it have a feed tension on the wire itself or just on the spool of wire?

Just a spring loaded nut squeezing the spool.

Seems that it may be hanging up as it goes through the liner creating a small loop then feed continues but now wire tightens on the crossed loop. Presume the tip is clean.

Yes, that was kind of my model of what was happening. But the spool is "upstream" of the drive rollers, and liner is "downstream". I can't figure out how a disturbance downstream in the liner could be felt at the spool. Making a birds nest at the entry to the liner would be more likely, I'd think.

Yes, I tried it with a clean tip.

Thanks for the feedback, I'll keep experimenting.

 

[Franko]

Good questions:
It's like a slip knot, where the outgoing wire tucks under the next loop, then comes out again the same side. I've had the spool off completely to make sure the wire started out wound properly.

The slip knot couldn't have happened while it was spooled up. It had to have happened when you changed the wire. The only way to untie the knot is to pull the tag end of the wire out of the stinger and feed roll and untie it. Or, you can remove the spool and untie it.

 

[turnitupper]

This exact thing has happened to me when changing spools. You snip off the wire blob at the torch, release the rollers and wind back the spool thinking that you can grab the wire as it leaves the liner because you don't want to put your filthy hands on the shiny spool. As you see the end of the wire emerging you have just enough time to see the first layer of wire turn onto something ALIVE. This is the time to slap your dirty paw over the spool to kill it. A clean piece if material held on the roll remedies this and negates the need for ungodly adjectives. Rewinding the spool is when you get your wires crossed.
John

 

[RJSakowski]

The slip knot couldn't have happened while it was spooled up. It had to have happened when you changed the wire. The only way to untie the knot is to pull the tag end of the wire out of the stinger and feed roll and untie it. Or, you can remove the spool and untie it.

A single half hitch knot cannot happen if both ends of the wire are contained. However, two half hitches in opposite directions can. Think of the way your bandsaw blades are coiled; they are a closed loop and you can't tie a half hitch in one but the coils definitely overlap.

Such an occurrence can happen if the wire is momentarily loosened. As the spool diameter decreases, the torque created on the spool by the roller drive decreases but the torque applied by the drag on the spool spindle remains constant. This in effect reduces the tension on the wire allowing it to unspool and windings to cross, creating the knot. Additionally, as the diameter of the spool decreases, the force created by the coiled wire trying to unwind increases, adding to the effect. A slight increase in the friction caused by bending the torch cable or by the wire sticking in the tip or hitting the work would be enough to momentarily upset the balance of forces and create the knot.

I would try increasing the tension on the rollers and on the spool.

In more than sixty years of dealing with auto-tied knots, I am convinced that rope, fishing line, string, cable, and wire were the first sentient entities in the universe.