saddle tank forming

[Fred_V]

i've been experimenting with shrinking metal to form the corner flanges for the saddle tank. no having much luck. i joined the metalshapers forum to find info on this but the flange is so small that their technique doesn't really apply, i think.

what have you guys done to form the ends of saddle tanks? what material and thickness?
thanks,
Fred

[david griner]

Hello,
You may want to consider making forming plates and flanging the sheets. I used this method for the tank on my current engine, ref. attached pictures. It can assume the radius you wish, especially when using heat.
Dave Griner

[Fender]

David,
Very nice-looking job! Are the ends of the tanks soldered in place? Is this steel? What thickness?

[Greg_Lewis]

Dave:

How about a detailed how-to on this? I think many of us could benefit from learning this technique.

[gwrdriver]

Fred,
This what I was going to suggest, but I didn't know what specifically you needed to do.

[Fred_V]

i have made a plywood form for the ends. this is a tank like is used on a Kerr Stuart Wren so it has flat top and sides with rounded corners. my problem is folding the corners. the radius is 1.25" so i haven't been able to just hammer it around as the metal wrinkles up. i'm experimenting with .020" brass and .030" galv. steel. i've tried making it shrink without success.

attached is a pic of what i want. the front flange faces to the back so it's hidden when finished.

[pockets]

Fred,
Plywood makes a poor hammer form. Perhaps it's enough for the brass. The brass needs to be annealed, repeatedly, during the forming process and the steel (consider loosing the galvanize) should be formed hot. This makes it so much easier to iron out those wrinkles.

Greg B.

[gwrdriver]

Fred,
I've only ever been a copper basher, with a weensy bit of brass forming along the way, but it sounds like to me this job is going to call for steel formers and backing plate, at least for the corners, and a lot of heat, so that you are actually doing more forging than bending. Not very long ago I formed a copper boiler front flue sheet from overly thick plate relative to the barrel diameter and I thought I would never get the pucker out of it, but with continued annealing and hammering it eventually came out.

[johnpenn74]

Making Flanges

Guys,
Tenn Valley RR Museum has a flanging machine in their shop I think. They got it several years ago. I never saw it run. It might be worth while to hit up the backshop gang and see if they have some advice on how the machine works and how you can apply it to our smaller problems.

JP

[Bruce_Mowbray]

There are a few skills that can be learned by running a flanger. One of them is patience. If you rush your project, you will get a wrinkle in the sheet and they are a bear to get out. One most often has to use the heat and beat method to remove a wrinkle or a pie shaped piece have to be cut out of the flange and the slice welded once the flange has been completed. Another skill is the ability to think about where metal has to "come from" in a stretch flange or where it has to "go" on a bunching flange. It's best to work gradually in both cases. Start flanging your metal together at the center of your curve. This will prevent a single "blob" of material from forming that you have to push along . Start in the middle of your radius and work outwards. Work slowly to prevents kinks and wrinkles. Also, trim your sheet to as close to finish as possible. This will reduce the amount of metal that you have to "bunch". For steel, figure on the neutral axis center-line being right down the center of the sheet thickness. For copper it's more like 80% on the stretch side and 20% on the bunch side. Brass is also around 50-50 I believe. As Greg said, make a steel form if you are flanging steel or brass. Aluminum and wood works for copper when the copper is annealed but use a good hard wood for your forms.

[marshall5]

Hi guys

I hope I can be of some help with this. Several years ago I purchased a part built Wren. The previous owner had had a go at flanging the tank end plates out of 20 SWG brass around a Tufnol former but had given up due to wrinkling on the sharp corners as described earlier. I decided to follow the designers alternative method shown on the plans. The new end plates of 1/16" brass were lasered to be a close fit in the wrapper but with no flanges. Short pieces of 5/16 by 5/16 by 1/16 brass angle were used to locate the ends and secured with countersunk 8 BA brass bolts. I made a press tool to shape the pieces of angle for the bottom of the tank where it follows the radius of the boiler. To simulate the exterior flange I simply used a strip of 3/8" 16 SWG brass with dummy rivets in it. The whole lot could then be sealed with soft solder. I am sure this is not the only way to do it but it worked.

Regards Ray

[Fred_V]

There are a few skills that can be learned by running a flanger. One of them is patience. If you rush your project, you will get a wrinkle in the sheet and they are a bear to get out. One most often has to use the heat and beat method to remove a wrinkle or a pie shaped piece have to be cut out of the flange and the slice welded once the flange has been completed. Another skill is the ability to think about where metal has to "come from" in a stretch flange or where it has to "go" on a bunching flange. It's best to work gradually in both cases. Start flanging your metal together at the center of your curve. This will prevent a single "blob" of material from forming that you have to push along . Start in the middle of your radius and work outwards. Work slowly to prevents kinks and wrinkles. Also, trim your sheet to as close to finish as possible. This will reduce the amount of metal that you have to "bunch". For steel, figure on the neutral axis center-line being right down the center of the sheet thickness. For copper it's more like 80% on the stretch side and 20% on the bunch side. Brass is also around 50-50 I believe. As Greg said, make a steel form if you are flanging steel or brass. Aluminum and wood works for copper when the copper is annealed but use a good hard wood for your forms.

thanks to all,
i have been experimenting using a suitable sized steel piece to beat the corners around using scrap pieces of sheet.

Bruce, i think i see what you are saying and you have given me some things to look at. the metal seems to grow and the flange gets longer (or wider). so i might try to cut it short to start with and let it stretch around the corner. my shrinking methods haven't worked. shrinking is an interesting process but i don't think it works on a short flange like this. i'll try some more tomorrow and maybe post a pic if i make any headway.
thanks,