Fitting and bonding corrugated metal roofing sheets

Sheet Metal Fabrication techniques, questions and help. "Tricks of the Trade"

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Re: Fitting and bonding corrugated metal roofing sheets

Post by Harold_V » Mon Jun 21, 2021 1:35 am

Bill Shields wrote:
Sun Jun 20, 2021 3:51 pm
I have one of those little torches and they are great for small parts.. like jewelry

The problem is going to be heat conduction away from the intended joint with a large piece of metal
Yep! And that's why I suggested that the small torch may work. Unlike a large flame, it will introduce limited BTU's, so the local area will be hot enough to solder, but not enough to spread far. Don't know that it would work that way, but certainly worth a try.

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Re: Fitting and bonding corrugated metal roofing sheets

Post by wernerml » Mon Jun 21, 2021 10:41 am

My grandfather built a roof for his 30" dia lawn decor silo using about 50 long, triangular strips of galvanized. (He was a plumber and had access to a sheet metal shop) He used a copper bar soldering iron in a holder using a ~1" diameter propane torch to heat it. He had a 20# propane bottle and a 10' hose on his torch. I know he was just using regular plumbing solder and acid flux. (at that time it was lead based solder) Using a torch directly on the joint tends to ruin the cleanliness of your prepared joint and burns away the acid flux. Torches work on copper pipes because the joint is protected between the fitting and the pipe.

Main thing with soldering is having a CLEAN lap joint. Very difficult to make a T joint. With your corrugated you may need to have a series of tabs on your end cap that will provide your mechanical strength, then seal the small gaps with solder. Cutting your end caps to match the profile of your curved corrugated will probably be your largest task. :-)

Last I saw that silo cap , ~5 years ago, it was still going strong after 45 plus years.

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Re: Fitting and bonding corrugated metal roofing sheets

Post by ctwo » Mon Jun 21, 2021 12:59 pm

I do have a rather large, old-school pencil soldering iron. I'd have to measure but the tip may even be larger than 1/2" round, and then give it a try. Or I may heat from the other side from where I'm soldering. My propane torch is a small 1/4" end.

The good news is that this is all already outside stuff with the usual flashing to protect the fascias, so if it leaks it will just drip where it is already getting wet.
Standards are so important that everyone must have their own...
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Disclaimer: I'm just a guy with a few machines...

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