Sputtering MIG Gun

[johnnycanuck]

Today I'd been fab'ing a small table made out of 14 ga. tubing and angle with my Hobart 140 for a couple hours when I noticed my arc was starting to sputter. The nice buzz was gone and in it's place was an intermittent phffft sound. I was getting blobs of molten metal but no good pool. Checked my ground, the brass nozzle, replaced the contact tip, checked the surface prep, increased voltage setting, adjusted wire feed rate...nothing helped. The last thing I did was hold the gun up and pulled the trigger to verify I had continuous wire feed. Finally asked Google and found suggestions to check the house circuit for low amperage, circuit board could be bad...all kinds of unlikely things.

Finally went back and started laying beads down on some spare stock and I noticed the wire was moving in-and-out from the blob and it hit me to try loosening the nut holding the spool. Sure enough, the buzz was back and I had a nice hot pool again. I think as the 10 lb. spool diameter was shrinking it was taking more and more tension to rotate it and eventually the drive roller started slipping. Guess it was just subtle enough that I didn't see it when pulled the trigger to verify my feed. I think it had been happening a bit all morning but worked well enough that I kept going. I better go step on that table.

Just thought I'd throw this into the ether in case other numbnut runs into a similar problem. Funny how things creep up on you slow enough you don't see a problem happening.

[John T]

Sounds like a gas issue.

(Unless you are using flux core)

[Mikel_24]

Sounds like a gas issue.

(Unless you are using flux core)

He already solved the problem and was just informing us. It is stated at the end of his post. Too much tension in the nut holding the spool.

Mikel

[Welder Dave]

Have seen where the tension nut on the spool starts turning with the spool either loosening or tightening the spool tension. It can be a PIA.

[opa]

this is very helpful information. i never would have thought of this, and i will keep a look out for it happening to me. thanks!

[N2 Welding]

Funny how things creep up on you slow enough you don't see a problem happening.

If you are using the same wire size and settings all day long then yeah I'd think you would not only see the difference but also hear it when it is changes. If you are constantly changing out spools with different wires and diameters for different jobs then it will keep you on your toes as to getting the settings dialed in every time. .02¢ good catch.

[tapwelder]

Check rollers(correct) and pressure on wire. Also was your cable wrapped overlapping? Gun angle could have been an issue. I think your "cure" may be inclusive if anything changed after the nut adjustment especially if you were getting stead wire feeds. Sounds like roller presser? Also, check to see your tension nut is assembled properly if you suspect it is tightening.

[John T]

I had a Lincoln SP125+ that would loosen up.
If I recall it had some kind of hokey plastic nut to tighten the spool.
I replaced it with a nyloc nut and warsher
that did the trick.

I think it was a common problem with those Lincoln SP models.