fixing a mig welder

[builder bob]

hello my school has a broken MIG welder and i kneed to get it fixed to be able to make the bike i want. i know it is 200 amp and auto feed but not to much else at the moment. i've never welded but want to learn. are there any common problems that happen on arc welders?

 

[DS13]

I know someone is gonna ask for em so take so of the nozzle and the insides.

 

[ML-TOYS]

You said mig and also said arc, which one is it ?

 

[Rustydog2010]

Autofeed? I'll bite -

I assume its a MIG. Check that it has wire in it. Have a look to see if the wire is being pulled though the feed rollers. That'll be when you pull the trigger. Then have a look at the nozzles.

We really need more info broseph.

 

[Doc Sprocket]

You said mig and also said arc, which one is it ?

Technically MIG is an arc process. The proper term for MIG is GMAW- Gas Metal Arc Welding. That said-

In order to determine where the fault lies, you need to test it! There's several things that could be wrong, but just looking at the machine is not likely to tell you much. The most common problems with wire feed welders are basically maintenance items. The contact tip could be too worn to use. The cable liner may be too dirty, or kinked. The drive rolls could be worn, or the tension could be misadjusted. The wire spool tension could be misadjusted. Heck, somebody could have reversed the polarity.

The more expensive but less common ailments could be a bad transformer, rectifier, or drive motor- or any number of components in between. You need someone who knows how to weld give it a try, and report the problem...

 

[builder bob]

Technically MIG is an arc process. The proper term for MIG is GMAW- Gas Metal Arc Welding. That said-

In order to determine where the fault lies, you need to test it! There's several things that could be wrong, but just looking at the machine is not likely to tell you much. The most common problems with wire feed welders are basically maintenance items. The contact tip could be too worn to use. The cable liner may be too dirty, or kinked. The drive rolls could be worn, or the tension could be misadjusted. The wire spool tension could be misadjusted. Heck, somebody could have reversed the polarity.
The more expensive but less common ailments could be a bad transformer, rectifier, or drive motor- or any number of components in between. You need someone who knows how to weld give it a try, and report the problem...

Ok I'll try and take it apart next week. The engineering teacher kind of knows how to weld. I will try and take some pictures. No body there can do much past getting an arc so when I asked what the problem was they just said it was broken.

 

[builder bob]

You said mig and also said arc, which one is it ?

My school has both but I guess I wrote that confusingly. I ment arc welders in general that time but the mig welder is the one that is having problems. Also, how do you tell what the current should be set at because they keep getting it wrong. All the welds look like A bird was pooing liquid metal all over the place.

 

[Doc Sprocket]

My school has both but I guess I wrote that confusingly. I ment arc welders in general that time but the mig welder is the one that is having problems. Also, how do you tell what the current should be set at because they keep getting it wrong. All the welds look like A bird was pooing liquid metal all over the place.

That could be a combination of bad settings, dirty metal, and/or a lack of welding skill. I'd have to see it.

I can't believe you guys have a machine sitting there collecting dust, and nobody knows how to use it or what's wrong with it. Just one more thing wrong with the educational system...

Before you start taking stuff apart- stop. You don't really know what you're looking for, and you may not be able to figure out how to take it down or put it back together. You have GOT to find someone who knows what they're looking at! Too bad you're not in my area. I bet I could save it.

 

[builder bob]

not knowing how to use the welder isn't the worst of it! we have a 3 axis cnc router and a cnc lathe neither of which anybody knows how to use, and two metal lathes!

there is a welding shop near by that might be able to do something but the place is so nasty; they're using a huge building with no ventilation, no windows and they don't open the door. the building is so full of smoke that you can see the path where someone walked! there's another place that I've never gone to where they make metal art. problem is i don't know any one who works at those places.

 

[Doc Sprocket]

not knowing how to use the welder isn't the worst of it! we have a 3 axis cnc router and a cnc lathe neither of which anybody knows how to use, and two metal lathes!

Honestly, that's just sad.

As for the welding shop, if I was anywhere near it, I'd peak. Where's this company's health and safety???

 

[DaiSan76]

Depends on how thick the metal is, but lets say you have a piece of 3/16ths. You want to start at about 18.5 volts and 195 wire speed. From there you can adjust the machine to your welding style. For flat and horizontal you want your wire speed about 10 over your voltage, and for vertical and overhead you want it even. eg: my typical overhead setting is 18.5 volts and 184 wire speed.

Does it feed wire when you pull the trigger? If yes, then does it try to arc, or not at all? If you have wire feeding, but it doesn't arc well the first thing you should do is make sure you have the right contact tip in. It may be something as simple as that you have a .035 tip with .030 wire. It could also be that the nut that holds the wire spool on is tightened too much, and doesn't allow the wire to move.

 

[builder bob]

Honestly, that's just sad.

As for the welding shop, if I was anywhere near it, I'd peak. Where's this company's health and safety???

Ya it's horrible. I have no idea what's up with the shop, there just poisoning themselves, I actually couldn't breath in there.

 

[builder bob]

Depends on how thick the metal is, but lets say you have a piece of 3/16ths. You want to start at about 18.5 volts and 195 wire speed. From there you can adjust the machine to your welding style. For flat and horizontal you want your wire speed about 10 over your voltage, and for vertical and overhead you want it even. eg: my typical overhead setting is 18.5 volts and 184 wire speed.

Does it feed wire when you pull the trigger? If yes, then does it try to arc, or not at all? If you have wire feeding, but it doesn't arc well the first thing you should do is make sure you have the right contact tip in. It may be something as simple as that you have a .035 tip with .030 wire. It could also be that the nut that holds the wire spool on is tightened too much, and doesn't allow the wire to move.

All of those are possibilities that I'll check next Thursday, they also are probably the cause because no one can rely use any of the stuff at my school. Can you use a MIG welder on aluminum, or is that TIG? Or both? I'm also pretty sure that it's a Miller welder.

 

[Rustydog2010]

Can you use a MIG welder on aluminum, or is that TIG? Or both? I'm also pretty sure that it's a Miller welder.

You can use a Mig to weld aluminum, but you will need a spool gun and wire to do so. Using the mild steel wire in it wont work overly well!

Tig can also weld both steel and aluminum, it just depends on the filler rod you use.

 

[builder bob]

then i was right again and the shop teacher was wrong! hahaha! now he can't complain about us not being able to weld an aluminum golf cart back to gether!

 

[mckutzy]

Tig needs AC, pulse helps and HF. AFAIK.... aluminum can apparently be also done with DC with pure helium. It is like O/A with electricity. TIG like any welding needs skill, but more so.

 

[DS13]

then i was right again and the shop teacher was wrong! hahaha! now he can't complain about us not being able to weld an aluminum golf cart back to gether!

Welding aluminium is not an easy task. Especially if u can't even weld steel to start with.

 

[Doc Sprocket]

then i was right again and the shop teacher was wrong! hahaha! now he can't complain about us not being able to weld an aluminum golf cart back to gether!

Where'd they find this guy? Can he at least read a tape measure? Man- every time I look, I lose a little more faith in the North American educational system(s). No bloody wonder nobody's getting into the trades anymore...

 

[builder bob]

he's a very good wood worker and he's good with engines but doesn't know to much about welding

 

[Doc Sprocket]

That may be the case, but I fail to see the logic in hiring a guy to run an operation when he cannot use the provided equipment. My logic works thusly-

I am stuck assuming the machine was purchased by and for the school because it was deemed a useful teaching tool, with an eye towards imparting a skill set on the students. I'm also stuck assuming that this occurred at a time when the class instructor was a fellow who knew how to weld. Fast forward any number of years, and now a new class instructor was hired. One who does not know how to use such a machine.

From a business perspective, this is totally illogical. Someone does not no how to use the provided equipment probably should not hold such a position. The guy is, after all, running a machine shop- and sooner or later, you're going to have to weld something in said shop!

To further this- even if he did get hired without said knowledge, why the heck hasn't he taken a course, scoured the 'net- whatever- in order to educate himself especially considering that he is charged with educating others!!!