Building a Sheet Metal Bending Brake

After finding plans for a home built bending brake on here, I wanted to give it a try. I picked up the steel from a scrap metal place for $37 ($0.25/lbs). The rusty angle iron was laying around in the dirt and was quite a bit stronger than in the plans. Fortunately, because I believe anything less strong wouldn't have been stiff enough (my bending brake is a bit longer than the one in the plans).

It took a while to remove the rust with a sand blaster and an angle grinder. What a chore.

In deviation to the plans I added another end plate to the apron to simplify the built of the hinges (see pictures). At first I planned to screw this extra plate to the first plate (which is welded against the apron). But I didn't have the right tap so I welded it all together. That was a mistake, because the hinges weren't positioned optimally (see below).

It was surprisingly easy to shape the bending edge with the angle grinder. The radius is 0.25" and I wrap a aluminum sheets around the edge to increase the desired bending radius, if needed.

I ended up having to correct a few things on my brake before it produced acceptable results. The main problem with my bending brake was the alignment and position of the hinges in relation the axis of the bending edge.


  • It is not easy to position the hinges. When you weld the end plates make sure the apron stays parallel to the fixed beam even when rotated up. Measure the width of the gap with a drill bit. Does the width of the gap stays constant during the entire rotation?
  • Use a long rod as hinge axis and stick it through both hinges. The rod ensures the hinges are in one line and helps position them relative to the bending edge. See the first picture.
  • My bending brake would not rotate far enough. The spring back requires you to rotate it way beyond 90°. My hinges blocked further rotation and I had to remove material, which wasn't easy on the assembled brake.
  • Don't position the pivot line too high above the bending axis. The higher it is the more the apron will move away from the bending axis and the less pressure it will put on the sheet metal. The pivot axis on my bending brake was too high. I didn't want to re-weld the hinges and mounted a 0.04" aluminum plate on the horizontal surfaces. That worked well.
  • Move the apron as close to the fixed beam as possible. There really doesn't need to be a gap when the brake is "open". Since the gap will widen when you rotate the apron you may end up with a too large gap while closing the brake.
  • Use a very strong handle. Mine is a 0.1" pipe and is already badly bent and even cracked. The forces to bend a 50" 0.063" 2024-T3 are incredible high!
  • The ribs of beam No. 2 (the fixed beam) in the plans don't allow enough room to bend a 2x2 C channel. I had to pretty much grind them away (see picture).
  • Test your brake with C channels. Measure the width of your channel at the ends and then in the middle. Does it stay constant? Chances are that the width in the middle is greater than at the ends. At first my brake produced unacceptable differences for that width. It turned out that the pivot line was too high. After reducing the distance between the bending axis and the pivot axis the width of C channels was only little wider in the middle. The apron is now forming the sheet metal closer around the bending edge because of the reduced gap between the two beams of the bending brake.
  • Verify that the beams you bought are straight. Mine were not.
  • Bend beam No. 2 (the upper fixed beam) so that it has a bow that points downward. With this you can apply pressure on the sheet metal in the middle of the bending brake by fastening the screws at the ends of the brake. A 12 ton bottle jack works very well to bend the beams. I found two parallel beams under our house. Before I found out about these I considered going to an unused rail way and use the parallel tracks. You will need two fixed parallel beams that are quite a bit stronger than the beams of your bending brake.
  • Consider leaving the brake unpolished and mount an aluminum plate onto the surfaces that are in contact with the sheet metal that you bend.
  • I think the maximal length of such a bending brake is pretty much what I have built: 50". The plans point this out too, but only after building it I also believe it.

Good luck building your brake!


The parts after cutting, removing the rust and polishing the areas that would touch the aluminum. Ready to be welded. The long rod through both hinges helps position the end plates and hinges.

straighten the beam 2
Bending the beam with a bottle jack under our house.

straighten the beam 1
Bending the beam with a bottle jack under our house.

Finished assembled

The apron swiveled up.

Is it 90°?

Bending a C channel. This is a 4" wide channel. You can image a 2" wide will hit the ribs of beam No. 2 while overbending it for spring-back. The next picture shows the changed rib shape because of this problem. Also, here the extra plate for the hinge is visible.

The cut-out ribs of beam No. 2.

The blue lines mark the edges of the bending radius and the red line is the center of the radius. I position the sheet metal so that the red mark is in one line with the bending edge of beam No. 2 (when I look down from vertically above it).

View from below. The apron is rotated up. You see the gap between the apron and the bending edge. If that gap is too wide the bending radius will not be precise.