MM251 snafu

[TXBuster]

Rock, or anyone else with an idea.

Hoping to remedy this without losing several days for Miller to get it fixed.

I have about five rolls of .030 hard wire through a pretty new MM251. Welder started popping and acted as if it wasn't feeding properly(like rusty wire). Took the opportunity to install new liner(correct length/no burrs), and tip. Welder still acts up intermittently.

Changed out drive rolls and checked allignment. Still probs.

Bead looks and acts as if you cut voltage by 1/3 and kept welding. It does not seem to be heat/time related. No kinks in the gun. Wiper installed on the wire. Can pull wire off the roll, through gun/ liner by hand with minimal effort. Am using same roll of wire and cylinder of 75/25 gas I was using previously. Tension is set right.

Any service bulletins, Tech. advisories, known quirks, etc.

PS- I guess I forgot my manners... This is a very informative forum with an intuitive bunch of folks. I may not say much but do quite a bit of looking.

[bjdenommee]

TBX

Check your cables, for the correct polarity.

Bernie

[Paychk]

Hello from another newby

I would start by checking the connections on your ground cable and the cable feeding power to the wire feeder mechanism. Don't forget to check both ends of each cable, if you have to open the welder to check the leads where they connect to the transformer, you may want a service technician to do this. If these aren't really tight, you can get the symptoms that you describe. This is because the resistance changes due to the heating of loose connections. This is the basic; anything beyond that and you may need a tech anyway.


BTW

Is the new liner the correct diameter? You may have gotten too big a liner and the wire can start bouncing around internally causing the sputtering.

[Roger]

You have discribed what happens when you loose shielding gas except for the holes in weld bead like swiss cheese. So that probably isn't the problem.

[bluesman2a]

Hey Tx: I had what sounds like a similar problem with 251. Are you getting a lot of spatter and very large adhesions near the weld (berries)?

If so, you might wanna check the threads I had on the 251 a while back search on my name and spatter.

The final resolution to mine was 2 different boards, and I believe the control circiut was ultimately the culprit. Rock and Mike helped me out greatly with my situation. Pictures can also help if you have the capability.

[TXBuster]

I read the thread to the post Bluesman2a suggested. I don't have excessive spatter- just what seems like low voltage for the wire speed. I can make 3-4 welds that look/sound great, then a string of bad ones, and back to good ones- ALL WITH THE SAME SETTINGS. I would think that would eliminate issues such as gas, stickout, run-in, technique, wire type/size, etc.

The changes that I made were made after the problem arose; the new liner, etc. didn't create the symptoms.

The connection issue that Paychk described could be the culprit. I'll check and get back with ya'll. Something I forgot to mention in my initial post is that I fab balcony and stair rails, and decorative fence panels with this welder. Lots of starts and stops with short runs. Could it be an accelerated wear issue on some of the internals??? Thanks, Bodie

[vipermanz]

i had this same problem before, i changed the tip and it made it better, then i moved the ground clamp closer, fixed it

[Big Nate]

Originally posted by viperchild
i had this same problem before, i changed the tip and it made it better, then i moved the ground clamp closer, fixed it

I would think he replaced the tip when he changed liners. BTW, a 251 amp machine is less likely to need the ground clamp 2" away from where he is welding. unlike the 110 machines

~Nate~

[Hobart Expert Rock]

TXBUSTER...........IF YOU GET THE CHANCE CAN YOU TELL ME WHAT THE OCV IS ON THE MACHINE..........THEN TELL ME WHAT YOUR WELD VOLTAGE IS AND THE GAS AND SIZE OF THE WIRE. I WILL ALSO ASK MIKE, MARIE, DOUG, AND KEVIN TO CHIME IN HERE ON THIS......................ROCK................
[email protected]

[Hobart Expert Kevin]

TXbuster,
A loose connection could definately cause what you are seeing.
If you don't find any loose connections that remedy your problem please give me a call @ (920)831-4898. I have an idea on what may be going on considering your application.


Kevin
[email protected]

[vipermanz]

Nate, when i moved the ground clamp closer i took a grinder and exposed fresh metal, maybe that's what helped me out.