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Home made sheet metal brake

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  • Home made sheet metal brake

    I mentioned on one of my threads that I had to bend a piece of metal in my home made sheet metal brake, and JD wanted pictures and info.

    I built this thing 30 years ago when I needed to get a decent bend on a 48" wide piece of 20 gauge sheet metal. Having just started my shop, buying things like metal brakes was pretty much out of the question, especially one that could bend a 48" wide piece of 20 gauge. I had a chance to look at someone's expensive store bought brake that was only capable of bending 30" wide metal, and figured for the money he spent, I could build my own.
    A few disclaimers, 1) I did not need a crisp sharp edge, and the one I build definitely does not provide a nice crisp edge. 2) My design is slightly less then perfect, but it does bend 48" wide 18 gauge metal. 3) This is a manual bending device, there is no offset weights, all the bending force comes from the operator. The thicker the material, or the wider the material, the more effort will be required to make a bend. I've been known to add a cheater bar to bend thicker or wider metal. 4) I didn't measure the frame work dimensions, you will have to adjust them accordingly, I will provide approximates on the length of stuff.

    The frame: (picture 2 with the bending surface, the bending bar and end plates, and without the clamp bar.)
    The frame structure is built from 4" channel iron. The bending surface is about my waist height, maybe 34"-36" high. The bending surface has the channel laid out flat side up and is around 54" long. I made one leg for each side, with the flat surface facing outward. The bending surface is welded to the top of each leg. At the bottom of each leg, there is a 4" channel standing upright on one of the flanged edges, flat surface facing outward. The bottom channel runs forward and rearward about 30", with the upper channel centered on its length. (Looking from the side, the entire leg is an upside down "T" with a flat outer edge). On the back side of the bending bar are 2 pieces of 4" channel that act as a material support. These 2 pieces are spaced an equal distance apart and are welded with the flat surface down, and the back edges are rounded off.

    On the underside of the bending surface channel there is additional support. Picture 1 It may not have been needed, but its there. That support is a solid piece of 5/8" round stock, and two pieces of 1 1/2" angle. The two 1 1/2" pieces of angle are evenly spaced apart with the edges trimmed so they can be welded with the open edge welded across (side to side) of the bottom of the 4" channel. The 5/8" round bar is welded at each end of the bottom side of the bending surface 4" channel, and across the 90 degree edge of the two pieces of angle. You will need to add a step bar placed to be placed on the top of the 4" channel across the bottom of the legs on the front side. In the act of bending the metal, you will lift up on the bending bar, and the step bar is needed so the break won't lean or fall backwards. I'm using a 11 gauge 1 1/2" square tube because I wanted to keep the opening between the legs clear.

    The bending bar (picture 3, viewed from the bottom)
    It is a 1/4" x 2" x 2" angle iron that is the same length as the bending surface, in my case about 54" long. Running the full length of the angle is a 1/2" x 2" flat bar stock that is welded to the inside of the 90 degree angle, so it splits the angle in 1/2. This is a needed support piece. Attached to what would be the inside edge of the bottom flange of the angle is the pull bar. This one is a round 5/8" bar stock. This piece is curved and welded to the inside of the bottom flange of the angle. As you can see there are several additional braces also welded to the inside of the bottom edge of the angle and attached to the curved piece. This curved piece is the bending force, and has a great deal of force placed upon it. When this is in place, the top flange is flush with the flat 4" surface of the channel bending surface, and the down flange sits against the front flange of the 4" channel bending surface.

    The end caps are 1/2" x 2" bar stock (picture 4) To the right side of the end cap is a pretty clear picture of the end of the bending bar. Also visible is the pivot bolt head. both end caps have a 1/2" diameter hole drilled through it about an inch in from the end, and about 1/2" from the edge. The holes in both end caps are in a uniform position. The two holes on the left side of the end cap were pre-existing holes in the material I recycled for this project and are of no importance.

    The most critical point:
    At the joint of the bending surface and the bending bar, on both sides, both the 90 degree edge of the bending bar, and the front edge of the 4" channel flange and flat surface are both cut back about 1" in from the edge. A 1/2" nut is welded to the bending bar. The position of that nut has to be positioned so that both the top flange of bending bar angle and the flat surface of the bending surface channel are flush with each other and both the bottom flange of the bending bar angle and the front flange of the bending surface 4" channel are against each other. It a good idea to clamp the channel flange and the bending bar angle together to maintain correct alignment. At this point, you also need to make sure the nut will clear the edges of the 4" channel, once everything is assembled.
    Now run a 1 1/2" grade 8 bolt through the end cap and into the nut that will be welded to the bending bar angle. Position everything so the center of the end cap bolt is centered at the sharp edges of both the 4" channel and the angle. A large part of the quality of all the future sheet metal bends will depend on how well this joint is done. When you are confident you have good placement, tack weld the nut to the bending bar on both sides. Once tacked into position, remove the bolt, and unclamp the bending bar, and finish welding the nut into position. Be careful not the damage the threads in the nut. Once the weld has cooled, insert the both through the end cap and into the nuts that are welded to the bending bar. Clamp the bending bar to the edge of the 4" channel making sure the surfaces are flush. Now tack weld both end caps to the 4" channel in several places. Remove the bolts through the end caps and unclamp and remove the bending bar. Finish welding the end cap to the the 4" channel. After the welds have cooled, clamp the bending bar back in position, and insert the bolts through the end caps and tighten until a slight drag occurs. Remove the clamps. The bending bar should be able to pivot up at slightly more then 90 degrees to the bending surface. Clearance whatever needs to be clearanced so it will move freely. Picture 5 gives you an idea what it will look like. I'l try to get a better picture soon. Almost there!

    About the only thing left is a way to clamp the sheet metal to the 4" channel so the bending bar can do its thing. We need a clamp bar. Picture 5 shows a view of the clamp bar I've been using the last 30 years. Picture 6 shows an end view. It looks pretty complicated, but really its not.
    We have about a 50" long piece of 1/4" x 2" angle with a 54" long piece of 1/4" x 3" flat stock welded to the edges of both flanges of the angle to form a triangle. The angle is centered on the flat stock, so that 2" of the flat stock stick out past the ends of the angle. The clamp bar sits on top of the 4" bending surface with the 3" flat down (mating up with the flat surface of the 4" channel). Both front corner edges of the clamp bar will have to be notched to clear the bolt that holds the bending bar angle to the end plates. After the notches are made and the flat surfaces are ground flat, the front edge of the clamp bar will sit at the parting line between the 4" channel and the bending bar angle. The metal will sit between the 4" channel and the bottom of the clamp bar, then as it gets bent, it will bend up between the clamp bar and the bending bar, so don't make the notches any bigger then they need to be.

    I clamped the clamping bar to the 4" channel to hold it in position on both sides and drilled one hole through the extension beyond the angle on the clamping bar, and also through the 4" channel, one hole straight through both pieces at one time. Then I tapped the hole in the 4" channel for a 3/8" bolt on both sides. Then I drilled a slightly larger hole then the 3/8" using the hole in the flat stock of the clamping bar as a pilot hole. I made two "T" handles using two 3" long 3/8" bolts for each "T" bolt. Then I drilled a hole in two short pieces of 1/8" x 2" flat stock with a slightly larger then 3/8 hole and inserted the end of the "T" bolt through the hold just drilled, and then bottomed a 3/8" nut on the bottom of the "T" bolt. I positioned the clamping bar over the two tapped 3/8" holes and screwed the "T" bolts through the holes in the flat bar stock of the bar clamp. The clamping bar should sit down flush to the 4" channel, and clamp tight with the "T" bolts. Then I welded the two 1/8" x 2" flats to the ends of the angle that is part of the clamp bar just above the nut on the tightened bar clamp. These two 1/8" x 2' bar stock pieces should lift the clamping bar as the T" bolts are loosened.

  • #2
    Duh, Pictures!


    • #3
      A couple things I would do differently the next time:
      1) When I built it, I drilled and tapped the 3/8" holes for the clamping bar in the center (front to back) of the 1/4" flat bar. I'd probably move those two holes closer to the front edge. There is a lot of stress on those two bolts, and as the metal gets thicker or wider, the clamping bar can lift and shift backwards. One tends to crank down on those bolts pretty good, and over the years, one of the holes has stripped out. Now I use a Vice grip to clamp down that one side. Moving the bolts towards the front would improve the clamping force, using larger diameter bolts would probably help too. These days, I am also adding a large "C" clamp over the clamping bar and the 4" flat surface somewhere near the edge of the metal I'm bending, when the bent metal isn't too wide. A completely different clamping method might be better, but this brake has bent a lot of steel.

      2) The front edge of the clamping bar is 1/4" thick, I suspect that if I put a radius on the top edge, and leave the straight edge on the bottom surface, I might get more crisp bends.

      The three biggest issues are the lack of clamping force, especially at the center, the lack of the crisp bent edge, and the lack of a counterbalance that would reduce the effort of making bends on thicker or wide metal. Gene.


      • #4
        Thank you Gene! I find this very helpful and will be making something very similar.


        • #5
          Happy to have helped. If you need any specific pictures of any area, I'll see if I can get them for you. Gene