First welding repair on Bodhi
 

After 10 years of whining about rust, I finally learned how to weld and just completed my first welding repair on my 87 300D. I took stick, MIG and TIG courses this summer (I'm out of work, so seemed like a good time to branch out), which I really enjoyed and picked up well. This thinnest material we worked with was about 11 gauge, so when I went home and tried thin sheet metal, it burst my bubble a bit. ;) I'm definitely struggling with it and planned to mess around with my 240D before touching this one. But I decided to address a "pinhole" in the trunk pocket that I thought I could fix with a little putty and, well, you know how rust is. Turned out to be a huge hole. I decided to just jump in and try a welded repair. Didn't have to be pretty, and it isn't! But the rust is gone, and solid metal again.
I had to do three different patch pieces because of the location ... basically a corner alongside a pinch weld. Fitting the pieces was a bear, and where I ended up with gaps, I blew through. Then I figured out about sticking a piece of copper behind the gap and that helped. Mostly I got things to line up pretty well with a lot of effort.
It was not an easy first job since it involved a lot of awkward positioning while welding, and I couldn't see a darn thing. Plus I just made a lot of beginner mistakes with settings and so forth. I used MIG with .025 wire and 75/25 gas.
Here are some pics. I'm looking forward to trying more (probably on the 240D next) and learning to make them a bit nicer!
First five pics: rust; cut-out rust; welded-in piece that is the inner side of the pinch weld (viewed from exhaust tunnel); bottom piece viewed from trunk; and outside piece. Both the bottom piece and outside piece bend down or out to form the outside of the pinch weld.

More pics: 1) lap weld holding the bottom of the outside piece to the bottom piece ... I believe it was spot welded here originally but I decided to zip the whole thing up. This was the last part I welded and I think the nicest (improvement). :) 2) different angle of outside piece, so you can see how I tried to make pinch welds. 3) inside the trunk, after priming. 4 and 5) LOTS of seam sealer.

Finished look. I didn't grind or use any filler because once the wheel is on you can't really see this area anyway (and it's very hard to get the grinder in there). I put on primer, then seam sealer, then undercoat, then a light coat of gray paint to sort of blend with the rest of the wheel well (the undercoat was black). I skipped the undercoat inside the trunk.
Aside from the lumpy bits, I think I did OK recreating the shape of the area. It's not a concourse job but I am proud I finally learned to weld on a car, and can't wait to fix all the other spots.

Nice! Welding definitely takes practice. I TIG welded Aluminum in HS for my FIRST Robotics team (we were Crush 1011) and it took a lot of practice to get acceptable welds. I used any time after school I could get to practice. TIG welding Aluminum needs AC current and it was loud so my teacher didn't let me practice if there were other students studying for the conceptual physics class we all took. :(

Cool, I did do some TIG in class on 1/8 inch steel and aluminum and I think it was my favorite process. I have not been able to try it at home because even though my machine will do TIG steel I can't really budget the gun and pedal kit right now. Maybe a Christmas gift. :)

It is the best process but also the hardest to do correctly and the most involved. For most stuff I'd choose MIG because you still get nice clean welds even if they aren't a stack of dimes. It's funny, the robot team was in the opposite situation as you. We had a TIG machine and a MIG machine, and we didn't have a spool gun for MIG welding Aluminum. That's why we just used TIG. :D

Bodhi, great work! What welding machine are you using? I took basic stick welding at my local community college winter before last. I was the resident geezer in a room full of 18-25 year olds. Only one other guy older than that. I was the only guy wearing a respirator also.... After one ~2 hour session early in the course welding without one, I blew my nose and it wasn't pretty.... Wore one from then on. I really enjoyed the course.

We dabbled at MIG, but no TIG. Would like to learn TIG.

Rgds,
Chris W.
'95 E300D, 449K

I have a Lincoln 210 MP which will do stick, MIG and TIG. Only thing it does not do is AC, so I can't TIG aluminum (but I can get a MIG spool gun). It's a really cool machine. It was not super cheap but for the price it does a lot, and will allow me to continue expanding my skills.
I've been wearing a respirator even though I'm not doing anything heavy now. I'm trying to keep the ventilation good but obviously I don't have any kind of extractor. I have been putting a couple fans pointed away to draw the fumes off a bit, and put the car near the garage doors and had them wide open. I also had a lot of fire extinguishers, a squirt bottle, a hose ready and a bucket of water nearby. I'm an elaborate worrier, but I think it's a good thing in this case.
Also, I know what it's like to be the odd duck in the class, since I was the only woman in mine! I was a bit worried going in, but everyone was really nice ... no one seemed to care about age, gender, background etc. It's a great skill to learn at any stage, and I'm glad I did it!

Definitely make sure you have lots of ventilation. If not, you'll end up with Parkinson's disease. :( That's what plagued my grandmother after a life of welding as a trade.

Metal workers verse, "What the welder giveth, the grinder taketh away"

Excellent repairs. Sounds like you had better equipment than I had to work with. I did the repairs to my 240D with a Harbor Freight flux core mig unit.

Obviously, I needed to do quite a bit of grinding, which didn't bother me. I'm happy with the results I got. But, your work is more than a hair cleaner than mine. :thumbsup2:

Thanks! I haven't tried flux core yet, but from what I've heard, the gas makes a big difference, so that helped me a lot. As long as you got the rust out and ended up with a solid repair, it's all good! :o

A word of caution from an old timer...

I have had a pre WW2 Miller HeliArc since 1972. Huge unit with 100 percent duty cycle. I was told by my welder friend who was selling it due to a divorce that it would weld one inch aluminum ... it came with a huge water cooled tip which I immediately changed out for a gas cooled one. It is AC/DC with infinite controls due to the screw handle on top moving the entire armature up and down. I love TIG and use Argon. None of that slag to have to remove... etc....

But this comes under the old saying of " If you are a hammer everything looks like a nail" .

Sometimes welding , as much fun as it is, is not the best solution for sheet metal repair. OR when using TIG or stick or MIG... you will need to basically use multiple TACKS instead of what you would think of as normal welding... this is due to needing to control heat warping of the sheet metal.... way better to control it than to have to correct it.

Sometimes butt welding is not even the strongest method to put sheet metal together.... the use of an offset flanger and hole cutter and Clecos along with brazing and solid steel rivets... since that may not take out the corrosion resistance the metal has designed into it..... and the ability to place the patch perfectly before attaching it... even though it may not be as much fun and might look like it was jury rigged together.... may actually be a much better repair.

so the rule is study sheet metal repair techniques before choosing the method of repair...

https://www.youtube.com/watch?v=lgEIVUVLrnQ

https://www.youtube.com/watch?v=6ZSxhj_2Avg

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Books

Famous custom car builders like Barris often used tack brazing through holes on offset flanges with wet cloths close around the brazing spot to control warping. Like on the original BATMOBILE...

https://en.wikipedia.org/wiki/Batmobile

Leathermang raises good points.

As far as your welds - pretty decent. You might try a higher flow rate on the gas and see if it makes cleaner welds. It looks like the base metal was pretty clean and that's important. I'm assuming that you jumped around a lot to keep heating dispersed and minimize warping. Don't be in a hurry!

You got quite a bit of spatter (I have "issues" with that too) and more gas and less distance from the shielding lens to the work helps. Also be aware of how much wind you have in the area where you're welding as it can literally blow the shielding gas off the weld leading to some of the issues you're having, especially spatter. Something they don't talk about in many welding classes is that IN THE REAL WORLD you often have to work on less-than-spotless metal - that's where the anti-spatter spray helps. Doesn't solve all your spatter but it sure helps!

I've spent many years welding on rusty sheetmetal (I used to do all mine with oxy-acetylene, a perfectly good method) and have picked up many tricks. It's NOT an easy skill to master and I haven't yet!

Dan

Good thots LM. Thanks.