Super frustrating Mig problemo.

Hey guys, here is the skinny. This thing has run well, but hasn't been used in a while. Lately it's been my numero uno, and it's been acting up. Its a Snap On (Blue Point actually) MB120. What it is doing is producing dark porous welds, sparking, popping and kicking while trying to tack. If I am trying to lay a solid bead down it's not terrible, but tack...forget it. I am running about 15-20 on the flow gauge, and the tank is full...argon mix. I have not detected any leaks in the gas line anywhere, brandy new regulator, .025 wire, and welding everything from 1/8" plate down to 18 gauge, its a nightmare. Any ideas? At one point I swear she was a good little welder, but this week has been fighting me and letting me down. It's acting like a gas problem but it's never happy unless Im carefully and I mean carefully steadily laying a bead. Any help or insight would be greatly appreciated.

 

Is your metal clean that your welding (ie rust)

 

Does your spool of wire have small rust spots on it from sitting a while ?

 

First thing I would check is your ground. Make sure the clamp is in good shape and the connections are tight at the clamp and machine. Keep your clamp within a reasonable distance of where you welding, within 4' of where your welding. Next in line, check your gun. Is the nozzle clean and free from spatter? Second is the contact tip gnarly? Take sometime and clean those items up and test the machine again. Still having problems? I would look at the wire next. Is it rusty? I see you live in Jersey, humidity will rust the wire. Net thing I run my welders at about 20-25 cfm on gas, try that and let us know.

 

You might wanna try a new liner, contact tip & a new bottle of gas - just to be sure.

 

My first thoughts are wire speed too fast or a loss of gas near the nozzle. A lack/loss of Argon at the tip can cause the porous condition, as I see you have suspected. Still, take another good look at the gun components to be sure a bad seal is not causing contamination of the shielding gas.
Both of our Millers had bad O-ring seals that caused weld porosity. It can be very frustrating to deal with.

 

Are you using an extension cord?

 

Yes, I was thinking a gas flow problem. My 35+ year old Miller just recently is doing the same exact thing; poor on tacks, fine on continous.

I put the nozzle near my ear, and the gas flow gets cut off depending on what angle the the welding feed cable is, right where it comes out of the welder.

If I support the lead so it comes out straight, the gas flows good. Pull it to either side, and it almost stops. Some sort of blockage on mine, or I'll look at those Orings like you said. Mine has a quick release lead with Orings at the base

 

Had a similar problem; nozzle was clear but there was crud in the fitting where the handle attached to the hose.

 

Maybe the gas solinoid if you hear gas when you pull the trigger it's probaly o.K. unplug your torch from the machine and check the continuity the trigger button is just the on off switch if your still not getting gas its a control card.

 

Ground Ground Ground check it out.

 

Put me down for the ground.

 

ground.....
metal prep....
wire.....
power source
on a 110 unit if they aren't 100% perfect you will have problems
...thanks to my dad for helping me string 220 to the garage

 

could be many things wrong, feed rolls slipping, liner pluged, tip no good, as for the gas an easy way to check is to put the tip into a glass of water and you should see bubbles, porosity is usely lack of gas, spitting is wire speed or power, have you ever checked the contacts?, if your using copper coated wire i would try blowing out the liner, some times the feed rollers can get a coating of copper and start slipping.

 

I have a different Snap-On welder MM140SL, but I had all kinds of problems until I examined the whole thing carefully. Fed up, I took the cover off and found several problems. I swear the thing was the last one built on a Friday after checks were handed out and it was approaching 5 o'clock.

My friend bought this used welder from his SnapOn guy. No idea the history there. For the short time he owned it, he used it very little and sold it to me cheap when he needed some cash. This is my first MIG.It didn't come with a manual. I have had it about 4 years and the performance has been spotty. Sometimes fine while other times making me want to pull my hair out. So I found manual and starting examining some things. I couldn't believe all the problems I found.

1. Wires to the whip microswitch had worn through and shorting to the copper crimped end of the gas line near where it connects into the system. Fixed this with electric tape. Could have been prevented altogether had the crimp not had a sharp edge or some sheath.
2. Wire bolted to the selector switch was very loose. Looks like it was never torqued down at the factory.
3. Controls transformer loose. All the rivets were never completely crimped so the transformer was loose. Replaced these with screws/nuts/locktite.
4. The gas line was pinched internally between panels from the factory.
5. Where the gas line connects to the solenoid was leaking. It was very loose and I could twist with my fingers. The line is not clamped so over time it just isn't holding as tight on the nipple. Cut it off a 1/2" back and reinserted. Added teflon tape to the threaded fittings. I added a cable clamp to keep it from twisting.
5. My gas line had loosened up where it screws on the front causing me to lose gas before it reached the tip.

Other mistakes I was making:
Wire feed tension too tight causing bird-nesting
Using Argon when I should have been using Argon/C02 mix

 

That's gotta be a gas problem!

 

100% argon is not your friend.

MIG welding mild steel should be a 75%argon/ 25% co2 mix.

New bottle of gas, could be labeled incorrectly, not likely but it is a chance.

Talk to your local welding supplier.

Make sure your ground is on a CLEAN area of bare metal.

Your Pal, Gary

 

replace the liner. they gum up over time, specially if you dont use a wiper on the wire and it'll come out in spasms

 

I have the same welder, and I remember a few years back there was a wire inside grounding itself on the inside of the case. I forget which wire it was, but remove the outer shell and take a look. Don't forget to unplug it from the wall!

 

1.check ground cable (both ends)
2.replace tip (for proper wire size. if tip is too big you will have problems)
3.check roller adjustment (again, for .024 wire, are you in the .024 groove?)*
4. check polarity
5.test weld on clean metal, w/ machine plugged in direct to outlet

* not sure about your particular machine, but many welders have the drive rolls grooved only for .030 and .035... you would need to change rollers for .024.

 

Thanks guys! I am going to fiddle more with it, I'll let you know what comes of it.

 

Hey unplug it take the covers off and look at the coils or transformers they loosen up I had Century mig and that is who used to build snap on welders it did this twice and blow it out while the covers are removed it helps them to last longer

 

Gas flow, oxidized wire, liner. My bet is one of these or combo therof.

Kirk

 

Is it possible to have oxidized wire without it appearing such? The wire looks clean, and I did find a gas leak and fixed it, but still welds terribly. I put the nozzle in water and pulled the trigger, which someone told me to do, and it bubbled like crazy, so its pushing out gas, also I upped the flow to about 25-30, but it made no difference. This is playing incessantly with the wire/voltage as well, nothing dials it in.

 

Yes. it can oxidize microscopically. Look at it reaaalll close. Or just swap out another roll and go from there.

 

liner my friend- bsides, its ususally a good idea to replace them periodically anywho

 

i had a miller sidekick XL that the wire feed motor went on, sometimes it welded fine, the next 5 times i couldnt run a bead.