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How much power is needed to MIG weld 1/4" steel in a single pass?

6.7K views 6 replies 6 participants last post by  smawgmaw  
#1 ·
I am in the process of buying a MIG welder and once I've built up my expertise, eventually want to build a driveway gate and a tandem axle trailer. That being said, the trailer obviously requires critical welds, and I want to make sure I have enough power to make sure the weld is penetrating the 1/4" steel correctly, and preferably in a single pass.

The unit I'm focusing on now is the Lincoln Power MIG 215 which is $1,170 at www.weldingsupply.com, the cheapest place I could find. The Lincoln brochure states that the maximum thickness for MIG on mild steel is 5/16" with a footnote stating that they recommend multiple pass welds on 1/2" material.

I had originally considered the SP-175 ($607), but the chart in that brochure states that the maximum gas-shielded MIG welding thickness is 3/16". The SP-175 can weld up to 5/16" with flux-cored, although the footnote states that would require multiple passes. There is no mention of multiple passes on the MIG capability.

The Power MIG 255C ($1,635) and clearly will do the job, based on the brochures comment that the maximum thickness for MIG on mild steel is 1/2" although they again say that they recommend multiple pass welds on 1/2" material.

The question I would like to have answered is - if you are a proficient welder and were making your own trailer out of 1/4" steel, would you do it MIG, and what sized box would you use?
 
#5 ·
Out of the units you have listed, my personal preference would be the PM 255, because of the added control over the weld puddle and arc that the variable voltage feature provides. Plus, the 255 offers quite a bit more power over the 215 for any thicker material that might come along in the future. The PM 215 however, is very capable of producing sound welds on 1/4" in short circuit transfer mode. The higher output power of the 255 however, gives you the option of using spray transfer on 1/4" and thicker.
 
#6 ·
Either the PM 215 or the MM210 would be a good choice. MAid difference would be color. ;) There is no reason I can think of not to use either one for 1/4" in a trailer application.
 
#7 ·
The PowerMig 255c is more expensive and would probably cost more to repair after your warranty ends. This is something you may also want to consider. Also, look at what the max thickness you will be welding and the thickness you will be welding the majority of the time. Do you really need the larger machine and are you willing to pay the extra? If you do, go for it. If you dont, save the extra cash for supplies.