Soft bends on metal

[Leatherneck]

I have some sheet 090 aluminum that I am making my hood piece out of and would like to do a soft corner, I could use a brake and put a bend in it but I would like a more rounded corner, any ideas?
Cardboard mock up

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Have the top cut and slotted. Once I get the top done then I will do the front piece. So any ideas?

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[helowrench]

Go into home depot/lowes.
get a 1/2" galvanised pipe long enough to fit the entire bend.
then find the size of pipe that it fits into, slightly loosely.
slit the large pipe into a half moon, lengthwise.
You now have a positive and negative former.
Clamp the ends, and knock the tube into the socket.
(copious smoothing and lubrication will be necessary to keep from scarring the hood..)

Or, draw it out on the aluminum, and head down to the local airport. Find the sheetmetal guy on the field that has a big brake, and ask him to drop it for you, and tell him the radius you want.

[bens collision]

depending on the strength of the aluminum, ( 4043 will bend easier than 6063 ) you can cut a hood 'form' , just the center to where you want it to roll, out of a couple sheets of plywood then router / sand the edge round where your roll will be. set your aluminum on top of that. now make another piece of wood to clamp on top of your aluminum so that the aluminum sheet is sandwiched in the middle of the wood sheets ( this will hold down evenly and not allow warpage). now you can either use a wooden mallet or a rubber hammer with a large head and SLOWLY work the aluminum over your rounded edge on your hood 'form'. ive made several fenders for medium duty trucks this way when i worked at a truck shop years ago

[flat_iv]

5052 will form better than both. Plus more easier to find.

[Ol'fogasaurus]

I worked mostly with 2024 (interiors of airplanes rather than using the 7000 series used for structure; primary or secondary) for bent/formed material and minor bracketry; as I remember, the 2024 might be a bit stronger in the .032 thickness but the 5052 is probably going to handle weathering better; even if the 2024 is painted I think you will do better with the 5000 series alloy. Either way I would paint either material on both sides.

http://en.wikipedia.org/wiki/Aluminum_alloy. I would read this through as it has some interesting things to consider concerning the alloying of AL.

Lee

[craigvwdude]

Just a tip, if you come up with a way to bend it, heat up the area to be "bent" with one of those little propane hand held torches. Makes aluminum soft!

[Ol'fogasaurus]

Heating AL is kind of chancy as the metal being heated can disappear on you usually w/out warning; one of the reasons it is usually solution heat treated. Also, you can change the temper or make it brittle (“Flame hardening is used to harden only a portion of a metal. Unlike differential hardening, where the entire piece is heated and then cooled at different rates, in flame hardening, only a portion of the metal is heated before quenching. This is usually easier than differential hardening, but often produces an extremely brittle zone between the heated metal and the unheated metal, as cooling at the edge of this heat affected zone is extremely rapid.. “- Wikipedia) I have seen people try to anneal it by running/waving a sooty flame torch flame over it if that is what you mean but then, if it works, it has to be either age hardened or re-treated as annealed metal is like working with a thin slice of American cheese.

http://www.steelforge.com/alloys/?alloy=6061 (I think this is for thicker materials)

http://www.mlevel3.com/BCIT/heat%20treat.htm

http://en.wikipedia.org/wiki/6061_aluminium_alloy

Annealing (-0) allows for making tighter bends than otherwise with heat/solution treated AL, depending on the hardness of the heat treatment, the minimum bend radius increases with the hardness of the heat/solution treatment; e.g., T3, T4, T6, T6511, etc.

Lee

[david58]

[Ol'fogasaurus]

Can't get it to work. All it does is send me to Twitter and someone singing is Spanish.

[david58]

Can't get it to work. All it does is send me to Twitter and someone singing is Spanish.

Try this
http://www.youtube.com/watch?feature=pl ... UDHiy0Qko=

[Ol'fogasaurus]

When I talked about ‘waving a smoky torch in front of the AL’, this process is what I was talking about. Also, they added some hole-less dimples which will help strengthen of the flat surfaces but still, they are relying on age hardening to strengthen the AL as well as the rest of the components of the tank to supporting everything. The chance of this oil tank getting banged up before hardening is probably much less than Leather or someone else forgetting and sitting on his hood.

Age hardening can take a long time to happen, sometimes years (I think that fact is in one of the URLs I posted or one of the other ones I should have posted) but in the case shown in the You tube video, the heat of the oil may speed that up too.

In Leather's case, he has a fairly long flat surface without too much additional support and no time for age hardening. The big radius bends are going to help some but remember how flimsy the annealed material was.

As far as the forming tool, it is something I have done before or used a homemade anvil for vice to accommodate the bending/forming.

Lee

[david58]

Leather would only be needing to heating the edges not the whole plate, the edges would be supported by the tubing. And attached with some sort of tab.

[Ol'fogasaurus]

It is still a weak spot and could unfold if too much weight or load is applied to it until it age hardens. As far as his toy goes; if he is careful and does not pass the point of no return with the heat and (it wouldn’t take much; notice the shape of the flame and the distance away from the material it is being held) not being over applied (I think at least one of the URLs I posted gave heat ranges), he should be able to bend things OK.

I‘m not against him trying it, I am just making sure he knows what has to be done;I don't think my first try at it was something this big or expensive. But, after all, I'm in the process of doing something I know is not the best thing to do.

Lee

[david58]

I agree Lee, but I was thinking he could test it out with some scrap material using heat, before he tries to bend the real stuff. This is just a skin not a load bearing part of the car.

[Ol'fogasaurus]

I've heard rumors of Leather's driving and I think that the hood it going to billowing up and down like a flag on the Marines parade field the fourth (I cleaned that metaphor up as you can see). Even if the hood is only 4' long and a couple of feet wide, there is going to be some flexing. We don't see many covered rails up here and the majority of those I’ve seen are 'glass covered.

The videos I have seen does show a lot of flexing (maybe I am reading too much into it) and that is my concern. If nothing else, the flashing off the flat hood it going to blind him at the wrong time. 

Think about it, hoods usually have a crease or two to eliminate some of the metal deflection. Back in the days of the SS and FX cars and the center of the hoods could be seen to suck in before they started to put “hickies” (scoops) over the air-inlet; if it didn't look so hokey I would recommend some bead rolling or something like that to put in some stiffening in the larger flat areas.

Lee

(Added) A ridge down the center of the hood might not be that bad of an idea. It will stiffen things up and reduce some of the flexing at the same time.

Starting on page 208 in the book "How to Build a Dune Buggy" by Earl Duty, they go into the making of body panels for a tube chassis toy. Their hood is flat but they do break the sides some which is what I was talking about. In the first section of the book they do show a bunch or "rails" some of which have front coverings over the tubes. I think Leather might have this book.

Lee