Recently, I needed 90 degree bends in aluminum stock to create brackets for a project I have going. I grabbed $25, ran to Home Depot and after a few hours created my own metal bending tool. Quick, dirty, simple and cheap.
The symbol " denotes inches.
Quantities come before descriptions of materials and are followed by an "x".
Images will be referred to in steps based on the numerical order they are placed within that step.
I used button head machine screws but in retrospect, it would be better to use flat head screws and countersink them.
Everything you need can easily be purchased at Home Depot or similar.
1) 1x 2" width by 1/8" thick flat steel stock
(I bought 36" of this for $6.97)
2) 1x 6" lengths of 1" Steel L bracket
(I bought 36" of this for $6.47)
3) 9x #8-32 x 3/8" machine screws (preferably flat head)
(I bought a box of 100 button heads for $5.80)
4) 2x #8-32 x 1" machine screws
(I bought a 4 pack for $1.18)
5) 2x #8-32 wing-nuts
(I bought a 6 pack for $1.18)
6) 9x #8 Lock washers
(I bought a 30 pack for $1.18)
7) 10x #8-32 hex nuts
(I bought a 100 pack for $3.92)
8) 2x 1/2" hinges
(I bought a 2 pack of 1.5" loose pin zinc hinges for $2.27)
This all adds up to just under $29 but if you skip the 100 and 30 packs of screws and washers and just get what you need, you should be able to get it down to $25.
1) Metal saw
(I got by with a hacksaw with a metal cutting blade)
2) Power Drill
3) 5/32" drill bit for metal
(just big enough diameter to get a #8 screw through with a little coaxing from a screwdriver)
4) 5/16" drill bit for metal
(not a must have but useful for cleaning up the edges on the smaller holes you drill)
(whichever type that corresponds to the machine screws you buy)
(For holding nuts while you tighten machine screws)
Cost: < $25 (not including tools)
Time: ~2 hours
Follow the Making...
Step 1: Cut Metal to Length
1) 4x 6" lengths of steel L bracket (see image 1).
2) 1x 6" length of steel flat stock (see image 2).
I cut these lengths the hard way using my hacksaw with a metal cutting blade attached. If you do not have any way of cutting metal you can pick up a hacksaw for cheap and get by. If you have a chop saw or band saw you can get through this stuff with, even better.
Note: Disregard the holes in the metal on the images on this step. We will take care of those in the next step.
Step 2: Drill a Few Holes!
In retrospect I should have purchased flat head #8 machine screws and counter sunk them as that would make the tool all that much sexier, as well as alleviate some of the issues I had with the screw heads interfering with the hinges fully closing. Thus, if you can, find a large drill bit you can use to drill countersinks after drilling the initial holes and use flat head machine screws.
Take the length of L bracket you labeled part "A" and drill one hole on the center line of one flange 1/2 inch from the end of the part (see image 1).
Take the length of L bracket you labeled part "B" and drill one hole on the center line of one flange 1/2 inch from the end of the part (see image 2). Note the difference in location of the hole between part A and part B.
Note: The hinges mount to parts C and D and thus, the hole placement is critical and will differ by what hinges you use. The critical elements are placing the holes appropriately so that the round part of the hinge is flush with the edge of the L bracket (see image 3) and mounting the hinges as close to the end of parts C and D.
Take the length of L bracket you labeled part "C" and drill four holes on one flange to mount your hinges to (see image 4). These four holes are for your hinges and it is critical that they are placed appropriately. Make sure you line the rounded edge of the hinge up with the edge of the L bracket when defining your hole placement.
On the opposite flange of part C drill one hole along the center line of the flange 1/2 inch from the end (see image 4).
Create part D just as you did part C but this time place two holes (one at each end, 1/2 inch from the end) on the opposite flange from the flange the hinges will mount to (see image 5).
Finally, take the 6 inch piece of flat steel stock and drill two holes as seen in image 6. The holes should be placed 1/2 inch from the end edges and 1/2 inch from the top edge.
Step 3: Ahhh, Screw It!
Using four #8-32 x 3/8" machine screws along with lock washers and hex nuts, attach the hinges to part C as shown in image 1. Again, note that the rounded part of the hinge should be flush with the L bend in part C. Now attach part D to the hinges using another four #8-32 x 3/8" machine screws, lock washers and hex nuts (see image 2).
You should now be able to bend the hinge with parts C and D attached. You can create an X configuration (image 2) or a T configuration (image 3, looking at the top of the T) based on how it is bent.
Image 4 shows all of the parts left to be attached to one another in roughly the positions they will be attached. Attach part A to part C (upper right in image 4) using the one hole left in each part along with one #8-32 x 3/8" machine screw, lock washer and hex nut. Image 5 shows part A connected to part C (left side) as well as part B connected to part D (right side). When you connect part B to part D you will want to use one of your long #8-32 x 1" machine screws and do not put a lock washer or hex nut on it. I also inserted a hex nut between parts B and D to reduce the parts from rattling around when the tool is not in use, however, this is not necessary (image 6).
Once you have everything looking like image 5, flip the tool over (image 7), and insert the other long #8-32 x 1" machine screw through the final hole in part D. Then, place the flat steel plate on the two long machine screws and place two wing-nuts on the screws (images 8 and 9).
Step 4: Fini!
You are now finished and can start bending aluminum stock at will to create the worlds meanest brackets to hold your Arduino or whatever else you need to secure. Just don't use it for evil. Unless its only slightly evil, then it's probably OK.
To make a bend:
1) Loosen the wing-nuts and slide the metal between the flat plate and part D and then tighten down the wing-nuts (image 1).
2) Grab part A and rotate it towards part B (image 2).
3) Rotate it to the appropriate angle you are trying to achieve, in my case 90 degrees (image 3).
4) Return part A to its initial position once the bend is made (image 4).
5) Loosen the wing-nuts and remove your newly bent metal (image 5).