Millar 211,M100 gun. It`s 8 years old . Working great until now. The solid wire is welding to the start of the liner just past the roller. Replaced the liner but the problem stays. My thought is the gun has a short. Ant ideas?
Thank you Eddie49. I`ll check out those recommendations and get back to you. I really appreciate you help. Peace, KenHello and welcome!
For the MIG torch to have a "short", it needs to connect to both the positive and the negative of the DC welding power source.
With solid wire, it is normal and correct that the torch tip, the thick internal power cable in the torch umbilical that goes out to the swan neck and the torch tip, and the liner ( if metallic ) all carry the positive voltage. In fact, so does the entire wirefeed assembly - the drive and pressure rollers, the gearbox, the motor, and even the whole spool of MIG wire. As such, all these components have to be isolated from the welder chassis.
What would not be normal is for there to be any chance of the negative of the welding power to reach any part of that group of components. Both sides of that DC power source are fully-floating, and do not touch except when the tip of the wire meets the workpiece!
The negative side ( which is often incorrectly called the "earth" ) should only be connected to the work return cable, the clamp, and the workpiece. It has no connection to AC mains Earth or to the casing of the welder.
I suspect that the socket for the Miller M100 torch is touching the chassis or front panel. However, that still doesn't explain how the negative side is reaching that place...
Does the work return cable exit through a grommet on the front panel, or via a Dinse socket? Are there terminals to enable polarity swapping for fluxcore wire? If so, check the insulation around those locations and terminals.
Hermetic, thank you for your recommendations. I`ll go thru the gun and see what I can see. I didn`t know there were plastic liners. A great tip. I`ll get back . Peace, Kenfor now try a plastic liner, the liner should not carry current, only the contact tip should be live, current is getting to the liner from some damaged insulation, try stripping the gun to look for bare cables etc.
Hope this helps
Phil
At 8 years old, I`ve only run 3 small spools thru it. It has a front plug in system with a knob to tighten and hold. But... a while back I ran out of gas and put in flux core and welded 20 minutes without changing polarity. Dumb! Will that mistake hurt my machine and gun? Peace, KenHello and welcome!
For the MIG torch to have a "short", it needs to connect to both the positive and the negative of the DC welding power source.
With solid wire, it is normal and correct that the torch tip, the thick internal power cable in the torch umbilical that goes out to the swan neck and the torch tip, and the liner ( if metallic ) all carry the positive voltage. In fact, so does the entire wirefeed assembly - the drive and pressure rollers, the gearbox, the motor, and even the whole spool of MIG wire. As such, all these components have to be isolated from the welder chassis.
What would not be normal is for there to be any chance of the negative of the welding power to reach any part of that group of components. Both sides of that DC power source are fully-floating, and do not touch except when the tip of the wire meets the workpiece!
The negative side ( which is often incorrectly called the "earth" ) should only be connected to the work return cable, the clamp, and the workpiece. It has no connection to AC mains Earth or to the casing of the welder.
I suspect that the socket for the Miller M100 torch is touching the chassis or front panel. However, that still doesn't explain how the negative side is reaching that place...
Does the work return cable exit through a grommet on the front panel, or via a Dinse socket? Are there terminals to enable polarity swapping for fluxcore wire? If so, check the insulation around those locations and terminals.
The change in polarity is to make the flux core weld better & give less splatter, not for the good of the machine. It will do no harm, just may not weld as nice. Some welding wires it makes little difference, others it does. You can stop worryingAt 8 years old, I`ve only run 3 small spools thru it. It has a front plug in system with a knob to tighten and hold. But... a while back I ran out of gas and put in flux core and welded 20 minutes without changing polarity. Dumb! Will that mistake hurt my machine and gun? Peace, Ken
Thank you Cobbler. As you can tell. I`m not the smooth weld on the work piece. I really appreciate you and others in the know. These forums are a treasure. Peace, KenThe change in polarity is to make the flux core weld better & give less splatter, not for the good of the machine. It will do no harm, just may not weld as nice. Some welding wires it makes little difference, others it does. You can stop worrying
Thank you hermetic. I will inspect the gun, [ Millar M100] as best I can. Your input as well as others, is greatly appreciated. Peace, KenYes, you can get plastic liners, but they are not very good! When I got my first MIG, a Clarke, which I still have and working well, it had a plastic liner, I was running a new spool of wire into the liner when the wire appeared through the side of the umbilical and kept coming! this is a major problem with plastic liners!! take out the existing liner, and check it for damage, check between the liner and the contact tip with a multimeter, there should be no continuity, has the wire feed pushed the liner up the umbilical until it has contacted the tip or connection to the tip? If your existing liner is plastic coated on the outside, check it is continous and tape any areas that are damaged. You can buy a new torch and umbilical complete from the net, but the best ones come from Techarc! Does your welder have a eurotorch connector, this would make fitting a new one easier and theyare only about £35-40.
True, but if the wire is welding to the liner as soon as it leaves the roller then obviously a potential difference exists between the wire and the liner. If this is a live torch type welder where the trigger just turns on the feed motor, then perhaps the liner is earthed out somewhere, or the feed rollers are supposed to be isolated from the welder but are not, Can the OP send us some pictures of the welder, and wiring diagram if possible?The MIG wire becomes "live" because it runs through the contact tip. Thus every part of the torch, the umbilical, and the wirefeed assembly that touches the wire is also "live", and, if it is metal, this includes the liner. None of this matters, because all these items are at the same potential. The only other connections there are the wires for the torch trigger switch, and these are insulated. Current can only flow - i.e. a "short" - by contact to the other side of the fully-floating DC welding voltage. This is present at the work return cable and clamp, and that is ( or should be! ) far away, until they meet at the workpiece.