Sheet metal gas tanks

[BigSand]

My hobby is working on vintage and antique outboards. Last year I had to make
a new gas tank, using the old rusty tank for a pattern. The side panels were very
tedious, as they have a "tight" double flange that allows the top and bottom
panel lips to engage into, then of course it's all soldered up. I used angle iron,
a hammer, a flange pliers, etc., to make those double lips. What would be a better
way or technique to make these double flanges? What equipment would make
this job easier, and not need a loan to buy them! Thanks.

 

[C-Bag]

I would suggest looking up Ron Covel on YouTube. He’s done several similar things and what he did was cut patterns out of MDF and hammer them over. Most times those guys don’t do square corners, they do rounded corners then TIG weld the seams instead of solder. I imagine you’re replicating the factory tank? A lot of their projects are out of aluminum. In this case I think they would not rust out but might be a bigger pain to mount up.

 

[BigSand]

I'll check out Covel. Thanks! I used a 3/4" piece of plywood cut out to
the shape of the tank, then hammered the 90 degree flanges over on
the top and bottom of the tank, so they ended up the exact same size.
It's the double flanges on the side panels that gave me a lot of trouble.
Yes, I was replicating the original tank so the mounting brackets,
fuel line hook up, etc., would all work. I don't do TIG, but soldering
worked out okay on the sheet metal tank. Thanks.

 

[Bi11Hudson]

Perhaps searching "hobby" airplane builders would offer some solutions. I'm not one, but had a couple of friends that have built home built airplanes. I recall discussions at work about fuel and oil tanks. There may be solutions in that hobby.

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[BigSand]

I would imagine anything built for an airplane wouldn't be out of soldered,
but perhaps some of the fabrication would be similar. I was just watching
a YouTube video on ductwork fabrication, and some of the seams they
make are very similar to what I need, but of course they have sheet metal
brakes probably worth $10k, lol.

 

[C-Bag]

I'll check out Covel. Thanks! I used a 3/4" piece of plywood cut out to
the shape of the tank, then hammered the 90 degree flanges over on
the top and bottom of the tank, so they ended up the exact same size.
It's the double flanges on the side panels that gave me a lot of trouble.
Yes, I was replicating the original tank so the mounting brackets,
fuel line hook up, etc., would all work. I don't do TIG, but soldering
worked out okay on the sheet metal tank. Thanks.

Ron Covel and Jere Kirkpatrick did a great collaboration on an odd duct that Jere found in a wrecking yard. Ron has done several collaborations and in each one it’s great to look at each guy does his part and how even though they used very different methods, their parts worked together perfectly. They both used wood like you did if you sandwiched the metal between the wood formers. its hard to know what your budget is but one of the tools Jere used to form with might interest. He used an air hammer with a nylon insert to what they call flow form instead using a regular hammer. They also use radiused corners. This is because on a radiused corner there’s someplace for the for the metal to go. It can shrink and stretch into the radius where a square corner there’s no place for it to go.

I know it’s not how the original tank was but with the radiused corners on the top and bottom of the tank and form the sides to that radius to the inside dimension of the top and bottom so it’s a tight fit. Then solder like you did. Of course if you want to spend more $$ there’s a bunch of great machines that can do this