Help diagnose MIG welder issue

[RoatanBill]

I've got a 15+ year old Lincoln transformer based MIG welder that maxes out at 88 amps. The best I can weld with it RELIABLY is 1/8".

I've lived with this thing for a long time but can't figure out what's wrong with it now.

SOMETIMES If I START a weld, the MIG wire balls up into a little ball and spits the ball at the weld. Then everything evens out and it welds as it should until it starts that balling up again. SOMETIMES if I START a weld it's as expected. No problem. Some welds are fine. Others have intermittent balling up somewhere during the weld process. There's no pattern to this. If this were a car, I'd say a spark plug (or two) wasn't firing. The sound is not bacon sizzling when it starts to ball up. It's like it's missing a beat.

I replaced the drive roller a few months back because it was slipping, and the new roller worked fine for months. I've tightened / loosened the pressure on the drive roller and nothing helps.

I've played with wire speed. I've watched the spool spin as I press the trigger. I've watched the wire just come out of the tip, and there's no jerking motion I can detect. I clean to bright shiny on everything and my ground clamp is fine; I checked it.

Ideas?

[455dan]

I've got a 15+ year old Lincoln transformer based MIG welder that maxes out at 88 amps. The best I can weld with it RELIABLY is 1/8".

I've lived with this thing for a long time but can't figure out what's wrong with it now.

SOMETIMES If I START a weld, the MIG wire balls up into a little ball and spits the ball at the weld. Then everything evens out and it welds as it should until it starts that balling up again. SOMETIMES if I START a weld it's as expected. No problem. Some welds are fine. Others have intermittent balling up somewhere during the weld process. There's no pattern to this. If this were a car, I'd say a spark plug (or two) wasn't firing. The sound is not bacon sizzling when it starts to ball up. It's like it's missing a beat.

I replaced the drive roller a few months back because it was slipping, and the new roller worked fine for months. I've tightened / loosened the pressure on the drive roller and nothing helps.

I've played with wire speed. I've watched the spool spin as I press the trigger. I've watched the wire just come out of the tip, and there's no jerking motion I can detect. I clean to bright shiny on everything and my ground clamp is fine; I checked it.

Ideas?

Is the screw in contact tip loose? bad contact on the threads will cause loss of voltage to the tip and therefore the wire which will cause the arc to drop out. just went through this with my mig last week.

[duaneb55]

Might help to know which specific machine you're dealing with. Code# will work.

Thinking out loud:
1) Have you ever tugged the machine around by the gun cable? Yes or no, the power cable may have pulled loose from the machine or gun end and making intermittent contact.
2) One or more loose/poor connections in the weld output circuit could be the cause.
3) Could have one or more bad diodes in the weld output rectifier.
4) Check the work clamp cable connection.

[Bluewelders]

A bad or dirty liner will cause problems, usually worse when the cable to the gun has tight turns or coils.

[RoatanBill]

The contact tip is securely tightened. I swapped tips when I changed the drive roller. It was working fine for a while so the tip and drive roller are not suspect.

It's a Lincoln Weldpak 100 with a gas kit. I've replaced the gas solenoid 4 times and Lincoln was never any help. I'm planning on a new MIG box around Xmas and neither Lincoln or Miller are going to see a dime of my money.

My welding cart weighs about 400lbs, so, no, I never attempt to pull the cart with the cables.
I replaced the 120V power cord with a heavier and longer one a few months ago. If anything, the box is getting better input that it ever did before.

I checked the ground circuit and it's fine. I replaced the cheap ground clamp on this box years ago for a heavy brass/copper one that could easily handle twice the power. I also keep the contact surface clean by gently sanding the contact surface to get rid of tarnish periodically.

The gun cable is just 10', so there's little chance of coiling it up. It's always near straight when I'm using it. The new box is going to have a longer gun lead and ground lead.

Although I have several brand new liners from buying solenoid kits, I can't replace the liner because the attaching mechanism is frozen. I attempted to undo the liner a few months ago and gave up because I think I'd break the wire drive assembly is I tried to undo the old cable.

[duaneb55]

Well, the Weld-Pak 100 certainly isn't Lincolns flagship machine and possibly only a half step - one at the most - above the best Harbor Freight offering. If you haven't been able to get the gun liner out it's possible the current one is damaged or extremely dirty.

Did you follow the gun liner cleaning procedure in the unit manual as an option to replacing it?

[RoatanBill]

Gun liner cleaning procedure?

Ah - what's that?

[AGW]

Gun liner cleaning procedure?

Ah - what's that?

[RoatanBill]

After your post I looked up cleaning the liner. That never occurred to me. I'll try it tomorrow.

I also found a video on Youtube that demonstrates the problem I'm having and it's all about a bad liner. I requested "cleaning MIG liner" and the video was one of the options.

Thanks for the suggestion.

[N2 Welding]

Liners are cheap enough. Pull it and inspect for kinks and lay it side by side with a new one so you can trim it to match the original length. On the other hand you might want to make sure the old liner is neither too long or short.

[RoatanBill]

I used my compressor to blow out any crud that might be in the lining, but nothing came out. I tried all the way up to 90 PSI and nothing.

I was ready for that solving my problem, so when nothing came out I decided to go for broke; either fix it or destroy it. Out came the tools and long story short, the fiberglass housing that is the drive mechanism is melted around the coiled liner. I used a Dremel to clean up the opening of the metal liner as there was melted fiberglass covering it with only enough of an opening for my .030 wire. The melt extends into the body of the mechanism and is why I can't get the liner out. I pushed as hard as I could and couldn't get the liner to budge.

That ended any attempt to fix it so I could replace the liner. I just put it back together again and then a miracle happened. It's working perfectly now. All I did was clean up a bit of fiberglass and crack about an inch of liner loose that I could get at and now it works. No more stuttering with glowing balls of melt.

I'll get a new box at year end and retire this one, but till then I think I'm back in business. Thanks for the suggestion.

[N2 Welding]

Good to hear it was an easy fix.

[Rangerhgm]

Nice.....easy fixes are always good

[Broccoli1]

There was a piece melted and a dirty liner and Lincoln was the problem?

[albrightree]

Drive housing melted into liner ? Almost sounds like the metal liner is carrying all the current... never had on get that hot.

[RoatanBill]

Brocoli1:

The liner wasn't dirty as nothing came out.

The reason I won't buy from Lincoln or Miller is because they don't support their products as per my personal experience.
I've replaced gas solenoids numerous times on the Lincoln. I've purchased the entire gas kit just to get the solenoid only to discover the brand new solenoid is dead right out of the box. Lincoln could care less. I tried purchasing just the solenoid thru Lincoln and their dealers and could never get one through that method. I had to resort to Ebay and get the solenoid from an Italian concern that has nothing to do with welding.

My little welder has had an electrical issue since new. I discovered that if the MIG wire spool has the very end of the wire wrapped so that it can touch the housing of the machine as the spool spins, when I pull the trigger the wire melts inside the machine from the drive roller back to the spool. This happened numerous times till I figured out what the cause was. Now I just snip that end piece flush with the spool and the problem doesn't appear. I'm certain these shorts led to the melted fiberglass.

I purchased a high dollar Miller helmet. It died in about 6 months and I don't weld every day. I could never get warranty service on that helmet.

My impression is that both Lincoln and Miller are rapidly losing market share because their machines just aren't that good any longer compared to the competition. They're super high end boxes for specialty welding may still be worthwhile, but their middle of the road boxes aren't competitive. Even if they were competitive, I still wouldn't buy from them given their awful support. YMMV.