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Discussion Starter · #1 ·
I need to put a lip or flange on a hole in 16ga black approx 11" dia. Ideally the flange would be no more than 1/4" and it doesn't have be at a perfect 90 degrees to the surface, but close-ish.

Something like a dimple die might work, but I don't think they exist that large - at least from what I've found.

Eastwood sells a hand fender roller that might work, but I'm not sure it'd do 16ga (how many fenders are that thick) and I think it'd take forever - - I'm looking to do multiple pcs here.

I think my only option may be to make my own crude die with some, say, 3/4" plate with an ~11" hole and ~11" disc that presses into that, allowing for material thickness plus a little.

Is there an easier or more readily available way of which I'm not aware?
 

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Custom made die on a stout bead roller?
Weld on a ring made of a rolled strip of the same material?
 

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Discussion Starter · #3 ·
Custom made die on a stout bead roller?
Weld on a ring made of a rolled strip of the same material?
I thought of the latter but sure would be cleaner and faster to just form it.

Thx for the reply tho!
 

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How many pieces are we talking about? Worth buying a HF bead roller and chopping it down so that the roller would fit inside the 11" hole? At that length, it would probably be stout enough to not need ridiculous reinforcements...

I'm not sure how you would crank the roller? Maybe offset the crank with some chain and sprockets?

Just thinking out loud
 

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Weld on a ring made of a rolled strip of the same material?
This was my thought, but for 1/4" it hardly seems worth the trouble.

Other thought was a plywood buck. Cut a hole and roundover the edge with a router. Clamp the plywood to the metal and use a body hammer to roll the edge over the plywood.

What is it for? Are you connecting something to it?
 

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Discussion Starter · #6 ·
All promising ideas, thank you! The body hammer is something I hadn't thought of and could work for small runs.

In simplest terms, the flange is just to reduce sharp edges and/or get them pointing down, and to add some rigidity.... I suspect it'll add considerable rigidity, just like dimple dies. Nothing will be attached to it.

Quanitity would be 10 minimum. Could be as many as 50.
 

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could always make a die using laser cut (or plasma) plate. Make it bolt together and use an impact wrench to pull it down. It will help to have guide pins to make sure the two halves do not shift.

-Dan
 

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Other thought was a plywood buck. Cut a hole and roundover the edge with a router. Clamp the plywood to the metal and use a body hammer to roll the edge over the plywood.
This ^^

I've heard this called hammerforming. I've got a dvd of techniques for replicating formed metal parts with wooden bucks and hammering the metal to fit the mold (Hammerforming Techniques - Covell/Fournier). It blew me away with what could be done and how repeatable it could be. Seems like the rolled edge under and then another piece on top, clamped, or better bolted, to the bottom piece, with a slightly larger hole would be the way to go. The piece on top with the slightly larger hole allows you to get a crisp edge without distortion of the rest of the piece. The dvd shows using a hardwood shaft and hammering on that against the lip to do the forming in tighter spots like this where swinging the hammer is hard. They called this corking.

Might help to anneal the piece first if you can. They also used both hardwood and aluminum for the forms, depending on how many pieces needed to be made.
 

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Discussion Starter · #10 ·
Well I did up a quick prototype-ish setup today and was pleasantly surprised by the results. It didn't get me exactly what I wanted as far as a 90-something degree bend, but it's more like an 11" dimple die, which will work for my needs.

All I had lying around was 3/16" plate and I was trying to use what I had at the shop. I took a bottom plate and on top of that placed a top plate with a hole cut 11.25". I found an old 11" pullhead in the scrap pile to go into the 11.25" hole. Add in material thickness of approx 1/16" per side and I've still got a little slop which is good I think.

I cut the hole in the work at 10.625 figuring an increase in I.D. of approx 3/16" per side given the 3/16" depth of my die, but of course that didn't work out exactly, which is ok.

And yeah, it (obviously) adds noticeable rigidity.

The piece on top with the slightly larger hole allows you to get a crisp edge without distortion of the rest of the piece.
Yep, this is the main problem I had. I clamped the work with a zillion Bessey F clamps but it needs to be sandwiched down to minimize distortion.
 

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