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Adding adjustment to MIG for sheetmetal


Guest Perry

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Guest Perry

Hi yall,

I had this idea a while ago but haven't tried it yet. I have a "Powermig" 110 amp that has 4 settings for heat. The lowest setting is just a bit too much for sheetmetal now that I started connecting the ground in a really positive manor in an attempt to clean up weld quality. I looked around the web for a good explanation of how the MIG works trying to figure out a way to add a lower setting or make it adjustable with a knob but came up with very little usable info.

I have the idea of lowering the input voltage using a variAC(I have lots of high current ones at work). This would give me good resolution on the adjustment and I should be able to turn the heat down as far as I want to. Any comments?

Does anyone have a good link that gives a MIG schematic so I can figure out what the heat is adjusting? I assume it is changing a transformer tap for the output voltage. anyone tried cutting the input voltage of a MIG before?

Perry

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I know on the typical cracker box type, inductance is the means of changing the output current. This way, the voltage stays the same but the current is adjusted. If this was the case, a variac would be something to consider, but a 2kva to 3kva variac is not cheap, even used or on ebay. Have you got the option of thinner gauge wire to run in your machine, or perhaps increase the flow of the shielding gas to carry away the heat faster?

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Guest Anonymous

Totally unrelated except for the Variac, but just for trivial knowledge if your asked, Eddie Van Halen used a Variac on his marshall amps to get the famous 'brown sound' he used. You'll thank me at Rock Trivia Pursuit... tongue.gif

 

Regards,

 

Lone

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Guest Anonymous

On my 2 heat settings "Crudsman" from Sears, I only use .023 wire and when doing sheetmetal, I place the ground faraway from the weld area to reduce the heat. A weak ground tends to lower the heat. Would a quality rotary dimmer switch work on the heat setting??I also use the argon mix with no substitutes

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Guest JAMIE T

Do what Dave said. Use a long extension cord. I've welded on my 240 with a Lincoln 135. I played with the wire speed and voltage for about a minute, and was able to run a bead WITHOUT burning through. Not just tack here and tack there, A bead. I was welding a plate on it to pull a dent out of the quarter panel(like on a frame machine, only not).

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Guest Perry

I'll give the variac a shot next time I need to weld sheetmetal. The long extension cord is doing the same thing, the variac gives you the effect of an adjustable extension cord. You can also clamp the ground farther away from the weld for the same effect.

I am using .023 wire, argon/c02 mix for steel, a vise grip as a clamp ground. I have a "powermig" 4 setting welder. with the l;owest settings and welding .070 sheet I can either weld or cut depending on how fast I move. It is very difficult to get a clean bead. I can weld thicker stuff real easy. Hopefully this will help. Thanks for the comments.

Perry

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Guest Perry

Ok, looking over the posts again I realized this wasn't clear, I want to plug the welder power supply into the variac. This will lower input voltage for the whole welder.

Perry

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If you try lowering the input voltage be sure to keep a fire extiguisher handy. flamedevil.gif I would also make sure I know where the breaker to the welder is in case you need to get to it quickly. Reduced line voltages generally cause things to overheat.

 

My solution would be to buy a better welder.

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Guest JAMIE T

A long extension cord will not lower the voltage(signifacantly). It will reduce the amperage getting to the welder. Keep the volts, lose the amps.

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