How to make a roof drain from sheet metal

[HotTinRoof]

Howdy,
This is my first post here. I am what you might call a complete novice at working with sheet metal. I actually got into it by accident, while repairing the old tin roof on my grandmother's house (actually it's "terne" -- steel coated in tin). Unfortunately, she had an inexperienced handyman paint it many years back and he used aluminum/asphalt paint, which corroded the tin and steel. I couldn't find anyone who knew how to fix it properly, so I've been learning to do it myself using the right technique, which is to solder on new terne sheet metal with 100% tin solder. I don't claim much expertise, but I've learned to make the basic roofing seams and solder joints.

Here's where I'm a little stuck. I need to replace the drain, basically with something like this, but made from terne


I already made the pipe using a steel pipe as a mandrel, and making a solder seam like this one:


I'm wondering if anyone could give me some tips on attaching the flat piece to the pipe. I could just put the two up against each other and solder, but I'd like to form some kind of a seam or link between them before soldering. I tried making a hole in the flat piece and turning the edges downward (into where the drain pipe will attach) using a cone-shaped mandrel, but I ended up ripping the metal. Like I said, I know very little about this stuff, but I'm interested in learning, so any suggestions from those with more experience would be very much appreciated!

Many thanks in advance!

[Harold_V]

I am not a sheet metal man, so take this with a grain of salt.

Try snipping narrow segments around the tube, each of which can be bent over @ 90° to couple with the flange. One on top, one on the bottom, one on top, one on the bottom, etc.. That will give you a mechanical coupling, then you can solder them for a seal and additional strength.

Welcome to the forum!

Harold

[HotTinRoof]

Thanks for the idea, Harold, that sounds like it could work pretty well. If I don't hear something different from a sheet metal guru in the next few days, I think I'll give it a try.

Thanks again,
Matt

[Dave_C]

Hot Tin Roof,

There is actually a tool made that will make these tabs for you and each tab will be uniform.

It is called a "Hand Notcher".

Inscribe a circle that matches your pipe ID, then inside that circle inscribe a smaller cirlce the depth of the notch. Cut out the notches and like Harold wrote, just bend the tabs down and solder in place. Some people like the tabs on the OD of the pipe and that is easy as well.

Hard to do on small ID pipe but anything 4" and larger is easy. On small pipe I just use Tin Snips and cut the tabs by hand.

Dave C.

[HotTinRoof]

There is actually a tool made that will make these tabs for you and each tab will be uniform.

It is called a "Hand Notcher".

Thanks for the tip, Dave, I think I'll pick one of those up this weekend. I was just thinking about how I'd use the tin snips to make uniform tabs, but it looks like someone figured that out already

If I have any luck I'll post some photos.

-Matt

[steamin10]

A small lip can be created on tin or galv sheet by dapping the edge over with a ball peen. It is slow going just tapping along, but it easy enough on a hard edge of a vise or piece of pipe.