Getting ready to pull out the gas shielded Miller wire feed MIG welder to plug weld my new rear floorpan into my '72. I'll be practicing on some scrap metal first, but would like some opinions on MIG settings to start with. Specifically shield gas pressure, wire feed rate, and current settings. Plus since the car is on jack stands, and I'll be welding overhead, any helpful hints on how not to get splattered, burned, or otherwise tortured while under there would be helpful. I have the shield, gloves, and I'll wear leather wherever possible. Don't have the luxury of a rotisserie for this one.

Your best bet for wire feed and amperage info should be with your welder as the settings may vary with different setups. I use a Hobart Handler 140. Inside the door there is a chart with recommended settings based on type of metal, material thickness and thickness of the welding wire. I found this chart to be an excellent starting point for setting up the MIG.

I believe floor pans are made from 18GA steel, so the settings for my Hobart using .030 wire are: heat setting 2, wire feed 30.

I set my regulator to 20PSI for the shielding gas on nearly all indoor work.

Welding upside down sucks. I would add a set of earplugs as well to your safety equipment. A friend of mine had some weld spatter fly into his ear and burned through his ear drum. As far as technique goes, try to position your body as far away from the welding area as possible and reach with one hand to the area you are welding.

Good luck with your project and keep us posted.

Yeah, it all depends on the welder. I find that there is no hard/fast rule for this stuff. There are just too many variables. Even things like the outside temperature and length of the extension cord can play. (At least in my experience.

Start with the least amount of amperage possible, and work with wire speed from there. You'll find the groove after 10-15 rosettes. Then the next 90-100 will be a lot easier.

Just make sure you move around a lot. (one side of the car to the other.) Just like when you torque down a wheel. one corner, then the opposite, than the opposite, than the opposite.

Also: If you can put the car at an angle at all, that'll help. If your jackstands are on the "3rd click" on one side, and "6th click" on the other, you'll have more of an angle. Just make sure you stay safe!

Not a fast job...but not a hard one either.

Good luck & take pics!

Thanks for the recommendations. 30 psi for the gas seems a bit high from what I recall from past gas shielded MIG work, but I'll start low with my scrap welds and work my way up until I get a clean spot. The protect the ears thing is definitely something I will do! I will try to post some pictures this weekend of how it goes on the 100 or so plug welds!

12-15 on a flow meter should be fine depending on your nozzle size. You may want to get a spot welding nozzle for your gun.

Get a welding jacket. I'm out of these but your local welding supply store will have these. I've been on fire while welding under a car on my back. It's kind of exciting but can go wrong really fast.
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I have a Millermatic 135 and it has a table inside the wire wheel door with suggested settings for different wire size, metal gauge, and gas type.

I've found the suggested settings need some adjustment and added the custom settings to the table. YMMV.