Modern Vespa

The gap is big in spots but l think it's totally doable. I think you're right that starting with a new piece won't get you much further ahead. The gap especially at the top seam might actually work in your favor for blending the slightly different curves.

There are a number of tricks mentioned that will help. Once you get it tacked in solid, you will have a better idea of which to use. There's always a trial and error part of it, take a break if you find yourself getting into trouble.

Thank you, and everyone for all the help! I'm amazed this is coming along!

Would it work to tack a strip of steel behind it and fill it in? Since it's inside the frame, it would be ugly, but hidden unless the tank was out.

This is how I would do it. I would use something heavier for the backing strip, like 16-18 gauge.

Thank you for this! I will follow!

I'm not sure I can fit a patch in there behind. If I do, it will be hard to attach. I might only be able to get the top part. It's very tight.

I tried to get the welder in to reattach one of the seat nuts, and it's almost impossible to maneuver in there.

that's a cork soaker of a job. I usually just slip a nut on a bolt and go in blind and hope for the best!

but Orwell got you set up solid. we expect to see this ready for paint by Sunday evening!

I hope I got it! Either that, or I welded the nut and bolt together.

This is the hard part! If I can get this, the legshield/floorboard and tail repair is not too bad. This might not be that far. Maybe 3-4 more days at the shop, hoping.

Then like bondo and such.

I saved the old floorboard for a template of where to drill for the rails.

Did you already order another panel from SIP?
If so, wait till it arrives before tacking it up, as you have an ideal template there.

I did order it!

It should be here this week.

I can probably redo this fairly quickly. I think I spent around 10 hours just shaping and drilling this one, so I'm reluctant. But the second time is always faster.

As a template it's probably good. Most of that time was slowly removing material to match something behind I couldn't see, then fitting, removing.

You slip the backup strip behind the sheet metal of the frame....

But you are drilling holes close to edge of the sheet metal of the frame (for plug welds) before you do.

So you are welding your plug welds from the outside to attach the backer plate, not from the inside.

The backing plate is thicker for strength and because if you have excess metal in the patch you will have to tap it down as you weld so you want some meat behind it.

What you have there is workable, but if you feel like taking another shot at it with a new patch, that's cool too.

Backing and filling will certainly work but it's going to entail a lot of grinding. Too much in my opinion/experience and grinding inside a curve is tricky especially with the overlap strip. I'd be inclined to use what you have as a template to make the second with gaps closed up. Think of the first one as practice and save it for possible future use.
I would also suggest you might reduce the number of plug welds as is seems a bit of over-kill to me.

Backer strip isn't a necessity, just a suggestion.

I have a bucket of scrap metal filled with patches I made that almost fit. I make fewer contributions to it after years of experience, but it still takes me a couple tries on more complex parts.

Another thing that came to mind was drilling out the spot welds on the patch and separating the halves. That might give you more wiggle room in your alignment.

Given that you got so close fitting the patch, you will know exactly how to cut the next one. The fitting always takes the most time, but you have already put most of that time in.

my 1/2 penny advice is along these lines as well. For my money, a 1/2" gap is way to much to fill and grind. Now adding a backer piece to fix the mistake as well. Its going to look not so great from the inside, and who know's on the outside. A little fillter goes a long way, but this seems like a stretch. Can it be done yes, but feels like putting a bandage on a bandage that doesn't fit anyway. You'll get a better outcome if you go back a few steps and fit the new patch properly. Make it tight and the welding will go quick and easy. Separating the 2 halves is a good idea too, that way you can tweak each side separately to get the best fit possible.

Yeah. The more I think about this, the more it makes sense to use a new one. It will arrive this week.

I spent so much time on the first one, but I bet the time I save on trimming/drilling will be eclipsed by grinding.

I think I can use the old one as a guide, and get it right this time.

That seemed like a lot of plug welds! I tried to follow where the spot welds go. There are about 20 of those on the sides. But they're smaller welds.

I think later bikes had more, too. Ps seem to have more than Rallys.

The bit I used for the welds is big, too. I was looking on welding forums, and a 7.5mm bit was recommended. It looks wide!

I'm afraid to separate the patch, bc the angles are so complex, and all seem pretty good in one piece.

stop lallygagging and weld it already!

*chants*
weld it! weld it! weld it! weld it!

Yes. This is getting tedious.

My next update will show some progress.

No worries. Go through your process and get it the way you want it. Greasy would just weld it and I probably would too but you're at a different place on the learning curve.

When I built my bus engine, I was often struck with analysis paralysis and went full metal micrometer on it over and over again and sweated every thousandth. It was only after getting the whole thing done that I learned what out of all that measuring actually mattered.

I had an older and more experienced friend who could do most of that stuff by feel helping me. He never tried to discourage me from measuring, but would remind me to feel for the fit of the parts.

Anyway, I'm blathering again.

This is a really key point though, though. Not blathering at all. One real aspect of knowledge about a process is knowing what constitutes "good enough" for varying levels of outcome--I was dealing with this exact problem learning wet sanding over in Going Plaid this weekend to figure out how much was "enough" at each stage of the process. And while I had to complete multiple stages to know if I'd done enough at any given stage, I could always go back and start over (to a point) if I didn't like the result. That's one luxury you don't have, at least not without a LOT more unwinding.

The help I have gotten here has been so valuable!

10,000 hours of vespa.

Ok. I tried again with a new piece. It's such a challenge!

I got the gap pretty close. Better this time.

Tomorrow I weld.

Hopefully I don't totally destroy it!

Nice improvement with the new piece. You can beld this in no problem. Take it slow and follow all the well experienced advise given in this thread. You're Rally will be looking good as new in no time. Well... some time, but you're getting close.

Thanks! I think it should work, if I don't totally warp it.

The corners on this piece don't line up exactly to the curve. It will take some hammer/dolly and bondo, I think.

I don't think they did on the original piece either.

I can do it!! It's all ready to start welding when I get to the shop tomorrow.

Inspiring to to see the effort and care here. Fingers crossed for ya!

It's going to look great when you get finished, at which point all the pain and suffering and cursing it took to get there will be instantly forgotten.

That looks good. You could go through a few more pieces and not get it much better. You will find that even if you get some burn through etc, you can always fix it.

Time to bring the fire.

if your next post doesn't involve burning metal I am going to choke you.






but seriously, great work man

I replaced a dogleg/wheel arch on my bus and spent forever fitting it. My retired army neighbor was helping out. As I stood there looking at it holding my welding torch I asked him, "Should I weld it"? He looked at me like, well you could stuff it up yer ass or make out with it. There were some surprises but it all got sorted out. Mostly with a big ass hammer.

Overcoming phobias.

I got this halfway done, and learned lots about it.

I ran out of argon gas, and I guess I need to buy my own.

The shop recommended using flux core wire, but it's very messy.

But coming along! This should work out!

That's been my experience with using a flux core VS gas shielding also.

Well done. You're getting there.

Looking good.
Flux core is fine for heavy stuff but not so much for light gauge. Good for outside where a breeze blows the shielding gas away.
Don't worry about the gouges and pin holes, they will get filled with a skim of 'bondo' . I assume you are going to paint this and not plate it. High spots are worse because they determine the thickness of filler around them.
I find it best to fill the plug holes from the inside out, starting with the wire touching the base metal in the center of the hole. That way I know I have bonded the two layers and not just filed the hole in the top one.
As for mating the curved corners, you could heat the metal to red and shape it down or, what I'd do is kerf the center of the 'corner' and bump it together to shorten the curve, if that makes sense. If you leave the new corner higher than the old, don't be tempted to grind them flush or you will reduce the thickness of the new down to nothing. Either way, you can fair it out with filler. As you noted, the floor mat covers much of the lower section.
I don't know if I threw this out earlier, but I find it helpful to see what I am doing wrong : Good luck !

You can always build up the gouge with weld material, but once everything is ground down and sanded, it won't look as bad. For gaps: sometimes I will stuff a couple strands of welding wire into a gap. It will melt when you weld and give you something to arc off of in the middle of the gap rather than burning the edge.

I would weld and grind all your pinholes and inclusions in the welds until the seams are solid and smooth. Moisture can get into them otherwise. It's time consuming but brainless work. Use the dremel for your fine grinding. It will be as good or better than a pro repair.

You got the hard part done. It's on there and fits well.

Nice job! I promise it gets easier.

Orwell, That's a good trick for gaps and I agree with you on the pinholes and inclusions. I take my comment back as I do the same thing .

Nice work HJO! The hard part is done-Melted Metal Milestone achieved!

Blending/flap disks are ideal there. You're gouging too much with the dremel.

You need to use it as flat as you can, on the weld peaks (lightly -- let the rpms do the work), not at the 45 degree angle you're gouging with.

Don't use 100% argon. Get 75% argon, 25% co2 mix.

Thanks!

I gouged with the Dremel, but the welds are still raised. Just knocked off some of the bulky welds. I'll try the file sander on those.

I got better at these as I tried more. Going to see of I can finish tomorrow.

I damaged one side of the corner. the are flat areas where I hammered to try to get it to match. And still too much space.

If I kerf, that means cutting a v, and placing together?

I guess the flat area might be too hard to straighten out, not sure how noticeable.

I found a paint shop! They do old lowriders and muscle cars. Quoted my $1500, but I have to get the paint. PPG paint is expensive!

I might use the VW L90E, which is almost identical.

Remember when I mentioned welding it at the corners first?

That was so that the bulge you have at the corner would end up at the top seam instead and it would have been easier to shrink...as you welded and tapped it down while it was nice and hot.

No worries though. You would have been fighting it somewhere anyway. Just how it goes.

You could try making a relief cut parallel to and between your blue lines maybe half to 3/4 of the length. Gently tap it down so the edges of your original seam meet. Tack it. Shove a dolly or something metal down the tunnel that will support the curve and tap it down from the outside. You are trying to shrink it. You might have to widen the relief cut if the edges begin to jam together. When you weld up the relief cut. Do the dolly and tap down thing again. Slowly and gently.

I hope that makes sense.

Thanks! That helps!

I tried following, but put the clamps right on the corners at 45 degree angle, and tacked next to it.

I think this piece is just wider than the other one. It seemed that way, a relief cut might be the only way here. I hammered when it was hot, and the other side fit together perfectly, but this side started to crumple.

I can always use a piece of the other if it's damaged, but hopefully is workable.

Too late to switch out that tank for steel mix?

From the net :
" What's the Difference Between Inert & Active Gases?

Inert Gas - Inert gases have no effect or reaction on the weld as it's an inactive gas. The main purpose is to shield the weld from oxygen and water contamination. An example of inert gas is argon.


Active Gas - An argon/CO2 mix is considered an active gas. Because it contains CO2, it causes electrical conductivity which affects the voltage of the arc and increases penetration. It also breaks the surface tension of the weld pool that is created which allows the molten metal to flow and flatten out. "

That's helpful!

I got argon, bc it's in a shop, and that's what they were using.

It's a small tank. I might need to refill again! Flatter welds are better!