RV Mudflap Bracket - TIG welding

[jakeru]

I TIG welded a cold rolled steel angle for a wide, continuous mudflap onto the frame of a pretty big recreational vehicle yesterday.



This RV is used to tow a trailer for a roadrace car. The trailer was getting "sandblasted" and the purpose of the wide rear mudflap is to keep this from happening. You can see the thick rubber "mudflap" off to the right in this picture.




We figured out where it should be positioned, and clamped it.

Then I marked it's location with both a tungsten carbide scribe and also a gray sharpie that it good for writing on black things




Then it was time to prep it for welding. That includes unclamping it, then giving the cold rolled some solvent (nonchlorinated brake parts cleaner out of a spray can is what I use) and paper towels just to remove the oil (so easy!)

The paint/undercoating on the frame, however, had to be removed in the area where I would weld, however, and for that I used a 4.5" angle grinder with 80 grit flap wheel and light pressure, being careful to not remove all of the scribe lines so I would not lose the position. I did follow that up with a quick solvent wipe as well. I removed the paint about 1/2"-1" away from anywhere I'd be welding:





Then, I TIG welded the bracket onto the frame. The materials I didn't measure thickness of exactly, but guesstimate the cold rolled was about 1/8" thick and the frame was about 3/16"-1/4" thick. I set my machine (Everlast Super200P) up in DC, started at around 150 amps but eventually bumped it up to 200 amps peak current. I dialed in about 4 seconds of downslope and used my torch switch to regulate the current level. It worked just great. You do need to vary the peak current and the downslope settings a bit to get them dialed in for what you're working on, but the result was very controllable heat without having to do strange footpedal contortions while laying down doing this work.





The owner was really pleased with how the welds came out, and I was too. (clean, no spatter, good penetration, good aesthetics, etc.) Some of these welds were tricky because of being on my back, and also at times only having one or a couple of positions where I could put my head to see what I was doing.

I did this outside and it was pretty gusty, so what I did there was put on a big #8 gas lens, and pumped up the flow to about double of what I would normally use, (and eventually had to bump it up to triple, so was running about 38 cfh at the end!) It actually worked great. I felt the wind blowing pretty hard some times when I was welding and the puddle stayed shiny. The wind only "got to" the puddle once, and that was before bumping the flow up to 38 cfh.