Setting up MIG for flux core--ran into a snag with wire feed

[2stroke1971]

I have an old MIG unti, "Brokand GmbH pocket MIG". It runs on 110.
I reversed the leads--that is to say I opened up the welder and reversed where the grounding clamp and the heavy cable headed out to the gun were bolted to.

Now, testing with a meter confirms that the ground clamp is indeed positive and the electrode/gun tip is now negative. So Im good there.

However, now the wire feed motor will not run. There is a switch on the gun that starts the wire feed. There is one black wire on that switch and it runs back to the sweeper on the wire speed adjuster, then thru the coil and back to the feed motor as a green wire.

Wire color aside, that was the positive lead for my feed motor before I switched the leads. With the gun originally positive, the feed switch on the gun simpy caused that one wire to conduct with the rest of the gun.

I disconnected the lead that went from the sweeper out to the feed switch and put a jumper over to where I put the ground clamp (now positive) and if course the motor ran. all the time with power on that is since I bypassed the feed switch.


Sooooo..... I no longer have postive voltage on that gun block for the feed switch to send back to the motor. Im thinking I could swap some motor leads, that is interrupt the ground wire to the feed motor and send it out to the gun block, and jump the hot lead over to where I moved the welders ground clamp (which is now positive)

nice, got a headache now.

any input appreciated.

[Willie B]

Most cases there is no need to fuss with the polarity of the feed motor. Check your manual, if you don't have one it may be available on line.
I've never had a MIG I needed to change polarity in the feeder motor.

[danielplace]

If what your saying is so then feeding the motor a constant positive and using the switch to connect the negative should do just like your thinking and make the wire drive feed again.

[smithdoor]

Most welders today have chart or table.
If do have one try internet for chart on your machine first.
Some heavy duty welders do not have charts and you do this from wire speed and voltage

If can not find it will take time but write down your settings.

I have an old MIG unti, "Brokand GmbH pocket MIG". It runs on 110.
I reversed the leads--that is to say I opened up the welder and reversed where the grounding clamp and the heavy cable headed out to the gun were bolted to.

Now, testing with a meter confirms that the ground clamp is indeed positive and the electrode/gun tip is now negative. So Im good there.

However, now the wire feed motor will not run. There is a switch on the gun that starts the wire feed. There is one black wire on that switch and it runs back to the sweeper on the wire speed adjuster, then thru the coil and back to the feed motor as a green wire.

Wire color aside, that was the positive lead for my feed motor before I switched the leads. With the gun originally positive, the feed switch on the gun simpy caused that one wire to conduct with the rest of the gun.

I disconnected the lead that went from the sweeper out to the feed switch and put a jumper over to where I put the ground clamp (now positive) and if course the motor ran. all the time with power on that is since I bypassed the feed switch.


Sooooo..... I no longer have postive voltage on that gun block for the feed switch to send back to the motor. Im thinking I could swap some motor leads, that is interrupt the ground wire to the feed motor and send it out to the gun block, and jump the hot lead over to where I moved the welders ground clamp (which is now positive)

nice, got a headache now.

any input appreciated.

[2stroke1971]

Thanks for the replies.

I got it working. I ran a wire from where I moved the "now hot" ground clamp lead to over to the sweeper on the speed control, and sent the negative side of the motor out to the gun block.

I havent tested it yet, leaving tomorrow for a week and have to get some stuff ready for that.

This welder came from a dumpster....I tried a couple years ago and the wire feed was terrible, kept jamming up. I shortened the conduit along with the sleeve and everything else to avoid a bad spot. Could never get it to stick well, lots of splatter.

Fast forward, I changed careers 3 years ago and have been doing a lot of welding at work, mostly TIG. I re examined this old MIG, and did some reading... and there were some other things wrong, like the feed roller. It had a smooth one on and I didnt think anything of it before.

The feed is nice and reliable now. Ill post an update when I test it!

Thanks guys!!

[2stroke1971]

Not a lot of luck with it....didnt play with it much though. Couldnt get a nice continuous burn going. The highest setting kept throwing my breaker and I got disgusted with it. Its been in the shed in a time out since. Ive been looking at buying a mig ...but I feel like I should try this one some more before I do.
I need to find another circuit to plug it in on.

[danielplace]

That will happen on some models. There was another guy that had same issue. If I remember correctly it is because the trigger switch was using the negative lead as one of it's wires then the switch in polarity tied the switch to positive so when you press trigger you are feeding another positive to the motor so it does nothing since it already has a positive and needs a negative to run. Two positives won't make it run. And if it has a contactor the positive side is dead unless the contactor pulls in so the switch would have a wire doing nothing going nowhere but to one side of the contactor. That positive isn't even positive as it is your weld output and isn't even hot until the contactor closes the same way the motor runs unless it is one of those hot all the time units.

[BD1]

Usually there are different rollers for flux core. Most are knurled.


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