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Sheet metal bending question

3K views 15 replies 9 participants last post by  41'srfun 
#1 ·
I have a pickup truck that I would like to fabricate a rear bumper for. The bumper is pretty simple in that I would like to fabricate a U shape bumper approximately 5 inches high with 1 1/2 inch sides. The overall length will be about 52 inches. The bumper is strictly for ascetics. I am not expecting any crash strength out of the bumper.

I tried fabricating by bending the piece over the edge of my work bench. I really wasn't pleased with the result. I made calls to local metal shops. I was given prices ranging from $200 to $400 for making two bends in a piece of sheet metal. It was explained that they have "minimum" fees.

I really don't want to buy/build a brake for this job. I was thinking about taking 4 pieces of 1 x 2 oak boards. Sandwich the sheetmetal between two pieces on either side of the bend line Using bolts and clamps. The two inside pieces of 1 x 2 would be cut at a 45 degree angle so that when brought together they would form a 90 degree bend.

Will this work? Am I over-thinking this process? How heavy gauge sheet metal could I reasonable bend like this?Any other ideas out there?
 
#4 ·
You can form sheetmetal like that It just wont be as sharp of an angle as having it done on a brake ...cut the metal to the overall width,sandwich the metal with the wood and fold the edges over,when I did it that way I did'nt use a hammer to fold the edges over I used a 12"piece of heavy square stock and started in the middle and worked to the ends when I used a heavier gauge sheet steel,I would hest it with a torch and bend,of coarse that would ruin the wood form and could only be used once. If you have a welder and enjoy fabricating theres lots of info out there and here on making your own brake...
 
#6 ·
I did this one time for an old style bronco. Used something like 3/16" stainless and had it bent at the same place I bought the stainless. The charge was minimal and after a bit of polishing, I had some great looking bumpers that were functional. You must be in a big industrial area to command such a minimal shop charge. I had a long, skinny stainless sheet metal tray for gun bluing made up for 30 bucks about 6 months ago and that included the cost of the stainless.

Trees
 
#7 ·
I am guessing you are limiting your gauge by what you can bend. When I need a bent part from something heavier then I can bend I score it with a grinder using a thin wheel. The thin wheels are very accurate. Once scored I bend it then weld the corner. I don't know if it would work for what you are trying to do. Just throwing it out there.




 
#8 ·
Underground said:
X2, BUT 2x5 isn't square ;)
First of all, thanks for all the responses so far. I'm taking notes. I did consider using box tubing. I rejected it for several reason, but a couple of them here:

Part of this exercise for me is the make this bumper appear to replicate a factory bumper, but at a much lighter weight. The box tubing I have seen in the dimensions I need is much heavier than I want to use.

Also, as I'm fabricating the bumper, I will be trying to fit other accessories such as lights, etc. into the bumper. I may need to vary the dimensions slightly as it is being fabricated.
 
#9 ·
trees said:
I did this one time for an old style bronco. Used something like 3/16" stainless and had it bent at the same place I bought the stainless. The charge was minimal and after a bit of polishing, I had some great looking bumpers that were functional. You must be in a big industrial area to command such a minimal shop charge. I had a long, skinny stainless sheet metal tray for gun bluing made up for 30 bucks about 6 months ago and that included the cost of the stainless.

Trees
In fact the places I checked were fabrication shops. I think the point was that they had enough work and didn't want to mess with a single piece like this, so they quoted me outlandish prices to scare me away. They are mostly doing work for the auto industry in Michigan.
 
#10 ·
deadbodyman said:
You can form sheetmetal like that It just wont be as sharp of an angle as having it done on a brake ...cut the metal to the overall width,sandwich the metal with the wood and fold the edges over,when I did it that way I did'nt use a hammer to fold the edges over I used a 12"piece of heavy square stock and started in the middle and worked to the ends when I used a heavier gauge sheet steel,I would hest it with a torch and bend,of coarse that would ruin the wood form and could only be used once. If you have a welder and enjoy fabricating theres lots of info out there and here on making your own brake...
I had not thought about using heat. By heating do you increase/decrease the possibility of cracking?
 
#11 ·
Metal bending problem

Your oak board idea will probably not work because the very point where the most stress is will be the point of the 45's. Clamping would be a b@@ch and how do you force the edge over?
I would start with a heavy I-beam (must be narrower than inside dimension of U) with an edge radius I like (1/4, 5/16, or ???). Clamp sheet metal at brake line with something like 2 x 2 square steel tubing(note: clamp over 1 1/2" dimension using welders deep throat clamps). Using a 12-18" piece of 2" Oak board - slowily -pound the 1 1/2" flange down. Work from one end to the other bending a couple of degrees at a time. Do not rush the process! When one edge is formed flip to other side and repeat process. Aluminum also works great for this if annealed (see online instructions) because it can be polished.
Good luck!! Hell luck has nothing to do with it - just take your time!! Patience grasshopper!!
 
#12 ·
Turdpolisher said:
Your oak board idea will probably not work because the very point where the most stress is will be the point of the 45's. Clamping would be a b@@ch and how do you force the edge over?
I would start with a heavy I-beam (must be narrower than inside dimension of U) with an edge radius I like (1/4, 5/16, or ???). Clamp sheet metal at brake line with something like 2 x 2 square steel tubing(note: clamp over 1 1/2" dimension using welders deep throat clamps). Using a 12-18" piece of 2" Oak board - slowily -pound the 1 1/2" flange down. Work from one end to the other bending a couple of degrees at a time. Do not rush the process! When one edge is formed flip to other side and repeat process. Aluminum also works great for this if annealed (see online instructions) because it can be polished.
Good luck!! Hell luck has nothing to do with it - just take your time!! Patience grasshopper!!
Yes Master. Seriously though, thanks for the thoughts. I like the idea of aluminum too, not only easier to bend, but also lighter weight. Only problem is I am not set up to weld aluminum which creates an altogether different set of problems.

I was kinda thinking though if I had some way to clamp both side, I'd be able to use my 235 lbs to force the bend.
 
#16 ·
I've made lot's of bends in light guage metal by laying out the line for the bend and then taking a skill saw, with a metal cutting blade on it and with the depth guide set really shallow and cutting about halfway thru the metal along the line. I guess this could be called scoring the metal. Then I clamp a peice of angle iron or something pretty rigid along the inside of the scored line and the metal will bend really easily by just pulling up on the outside edges until you get the desired angle of the bend. It works really good on 14 guage mild steel, but anything any lighter might be hard to score the line without cutting thru the metal.
An easier way to score the line would be to use either a die grinder or a cutoff tool with 1/16" x 3" cutoff wheels. The skill saw is a little harder to control if you haven't tried doing this before.
 
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