Introduction: Build a Sheet Metal Brake
I love building tools. There's been more than a few times I've needed to bend metal and I've resorted to clamping 2x4s together and using a hammer. I needed better.
I saw a how to on making a metal brake and wanted to make a few modifications. This is what I designed and built, adding springs to make the hold down pop up and ensuring accurate adjustability for material thickness.
The 2x4 is the base that will be clamped to a workbench when the brake is in use. An angle is attached to the 2x4 and another angle is bolted on top of that to hold down the metal I'll bend. A third angle has handles and is hinged to the 2x4. It creates a T shape with the base angle. The third angle is what actually bends the metal against the hold down. My hold down is slotted to adjust for the thickness of metal.
• (3) 1/8" x 1.5" x 1.5" x 4' Steel Angle - for hold down and bender, I had a scrap angle so I only bought two.
• (2) 1" x 3' 16 gauge Steel Box Tube - this will be cut in half for handles
• (1) 1.5" x 3.5" x 8' wood 2x4 - this will be cut to 48". Avoid framing studs, get a better quality stud.
• (2) Door Hinges
• (6) #10 x 1" Flat Head Machine Screws - for hinges to bender. I could have used smaller screws
• (4) #10 x 1-1/2" Flat Head Machine Screws - for handles to bender.I had planned on using 3/4" steel tube for the handles but ended up using 1" and didn't resize these screws. I got 1" which works, but I'd recommend at least a 1.25" length
• (10) #10 Nuts - for hinges to bender and handles to bender
• (16) 1" Drywall Screws - 4 in each hinge, 4 in the center plate, 2 in each adjustability angle. All of them drive into the wood 2x4.
• (32) #8 washers - between the hinge and 2x4 for correct spacing. I had these on hand, and (2) per screw put the hinge at the right height.
• (2) 5/16" x 2.5" Carriage Bolts - for the hold down. These run through the 2x4 and hinge
• (2) 5/16" nuts - Carriage bolts to main body
• (2) 5/16" Wing Nuts - for hold down
• (6) 5/16" Washers - for the nuts at the main body, for the top of the spring, and for the wing nuts
• (2) 3/8" x 1" Hex Bolts - for adjustability angles
• (2) 3/8" nuts - for adjustability angles
• 18 ga solid wire- for the hold down springs. You don't need much wire, but if you don't have any on hand this is going to increase the price a lot
• Spray paint - I bought one can, which is enough. I'm going to do this two tone though.
• $84, not counting 18 ga wire or tools. I spent $65 since I already had a few things on hand
• Miter saw with metal cutting blade
• Table saw for cutting the 2x4
• Hack saw with metal cutting blade
• Jig saw with wood cutting blade
• Drill and/or drill press with the drill bits listed below
• Metal punch and hammer
• Flat & Round File
• Router with a 1/4" round over bit
• Angle Grinder if you're using any scrap metal or to smooth out the slots in the angles
• 3/8" tap, size may vary
• Optional - metal spring jig and 5/16" steel rod with 1/8" steel spacer
Drill Bits Used:
• 1/4" for #10 bolts
• 1/2" to recess the #10 bolt heads
• 7/64" for dry wall screws threading into wood
• 5/32" for dry wall screws passing through metal
• 3/8" to recess drywall screws
• 1/8" bit as a pilot in the hold down angle
• 5/16" for carriage bolts
• 7/8" forstner for carriage head bolts recess
• 5/16" bit for the adjustability angles to tap the holes for the 3/8" bolts
• Saws can cut you. Always pay attention to how close your hands are to the blade and make sure you don't cut through anything unintended.
• When drilling, make sure you don't accidentally drill through anything you don't want to.
• Wear a respirator when grinding, cutting, or filing metal. You're creating small pieces of metal that float in the air. You don't want to breathe that. Also wear proper eye and ear protection.
• Spray paint must be used outdoors in a well ventilated area. A respirator or mask is required. Allow time to dry fully.
• Wear old clothes for painting. Chances are paint will find a way to get on your clothes.
I wear paint coveralls when working because I've messed up too many clothes. I usually have a respirator as most of my work involves cutting or sawing which generates dust I don't want to breath. I've got safety ear muffs I wear when using any power tools. I also have a full face shield because I like my face and eyes.
Step 1: Creating the Base
The first step was cutting the components.The 2x4 was cut to 48". I cut my scrap steel angle, which will be the center plate, to 36" with the 4" hinges flanking it. This leaves 2" on each end to clamp the 2x4 to a work bench. The other two angles were cut to 44" to reach the outside edge of each hinge. The center of the hinge pin needs to center on the joint between the bending angle and base angle. Later I will take the pin out of the hinge and flip the hinge so that the angles align. I used a metal cutting blade on a miter saw to cut the steel. A table saw cut the 2x4.
While I only bought (2) angles, I did have to grind the rust and paint off the scrap angle. It's 1/4"x3"x3" which is heavier than I need but the price was right.
While it wasn't really necessary, I cut out the front face of the 2x4 so that the center plate would sit flush. I put the angle in place and marked the edges on the front face with a pencil. I used a jig saw to cut the slot in the wood and a file to true the corners. I used a router with a 1/4" round over on the top edge since the interior of the angle has a slight radius. While I could have tried to flush the top, I didn't want to run the risk of not getting the top flat. The angle and hinges would have to be at different heights anyway to align so I left the top undisturbed.
I used a jig saw angled to 45* to cut slots for the hinges in the 2x4. The hinge pin needs to recess slightly. The base angle is screwed to the 2x4 with (4) evenly spaced drywall screws with recessed heads. The hole size for the screw through the metal is 5/32" with a 7/64" hold into the wood for the screw to thread. The heads are recessed with a 3/8" bit.
Step 2: Bending Angle
The bending angle is what folds the metal. I cut out 1/2" off each corner of the bending angle for the hinge cylinder with the hack saw and then smoothed the cuts with the grinder and file.
I used clamps and the 1" tube steel handle to hold the bending angle temporarily in place and aligned with the top of the base angle. The top of the bending angle and base angle must align. For the hinges to orient correctly and align the angles, I needed (2) #8 washers between the hinge and 2x4, (32) total. I had already pulled the hinge pin out and flipped the hinges. I had to re-drill the recess for the screw head in the hinge, since one side of the hinge is now reversed. With the hinges in place, I marked the screw openings on the 2x4 and drilled a 5/32" hole. With the folding angle still clamped in place, I marked the hinge holes on the bending angle, unclamped it, used the metal punch, and drilled 1/4" holes, recessing the heads with a 1/2" bit. It's important to center the hinge pin at the base angle and bending angle joint.
With the hinges and folding angle attached to the base angle, I clamped the box tube in place. The tube will serve as handles, and I spaced them 24" apart. I marked the holes for the bolts that would go through the angle and box tube. There are two bolts in each handle with a 1/4" hole.
Step 3: Hold Down Angle
The hold down clamps down the metal to be bent. I used a file to create a flat spot in the hold down angle, used a metal punch to create a start for the drill bit and drilled a hole for the carriage bolts. I did a 1/8" hole first, then the 5/16" hole. I then put the hold down in place and marked the hole for the carriage bolts on the hinges. I used the hold down angle as a guide and drilled through the hinge and 2x4 and used a forstner bit on the bottom side of the 2x4 to recess the carriage bolt head. My bolts didn't quite line up with the hold down angle, so I used a round file to enlarge the drilled hole to fit the bolt.
The hold down needs a slot cut out not only for the hinge but for the hinge to bend back. I cut out 1/2" the length of the hinge on each end with a hack saw and filed down the edge.
I discovered it would be nice if the hold down would pop up when not in use to allow metal to slide in easily. Trying to lift the hold down while sliding metal in was tricky. It hadn't been long that I made a spring jig and did a tutorial for spring making, so that worked perfectly. A compression spring would force the hold down to pop up when not clamped down. I already had wire, using 18 gauge. You don't need a jig to make the spring, it just makes it easier. You will need a steel rod that's at least the same diameter as the carriage bolts. Attach that to a drill. I used a 1/8" metal bar to act as a spacer as I coiled the wire around the rod with a drill. Go very slowly. Make more spring than you need. You need to cook them, but that's in my tutorial.
The springs are approximately 3/4" tall uncompressed. Originally they were much taller, but I had to cut them down after adding the spring perch. Originally I planned to slot the 2x4 and hinges so I could adjust for material thickness, but I didn't like the idea. I preferred to slot as few components as possible. Instead I slotted the hold down. I taped off what I needed to file out and used a round file to create the slot.
Tightening the wing nuts would hold everything in place. This worked in theory, but the washers that are at the top of the spring don't slide on an angle. They worked fine when centered inside the angle, but not when shifted. When shifted the washers would bind. I needed a triangular shape to facilitate the hold down sliding and to keep the washer in line. I wanted to make a metal angle, but didn't have the right gauge, so I created a spring perch out of 3/8" wood. The final spring seats are 3/8" thick, 1/2" is probably a better size. Each side is mitered at 45* the bottom is 1.25" wide and the top is 3/8" wide.
Step 4: Adjustability Angles
With the hold down slotted, I wanted a way to keep the hold down in place for a particular material thickness. While just the wing nuts could suffice, lining up the hold down for material thickness and trying to keep it in place invited error.
The leftover steel from cutting the 1.5" angles was used as a stop for the hold down. I cut the 1.5" angle down to 1". I didn't want it taller than the hold down or to extend past the 2x4 base. I drilled a 5/16" hold towards the bottom of each angle. The hole was tapped for a 3/8" bolt. The bolt head butts the hold down, acting as a guide. The bolt can be screwed in or out to account for metal thickness. A nut on the back of the bolt keeps everything in place.
When tapping a hole, you need cutting oil. Motor oil will not suffice as it's designed to stop metal to metal contact. I didn't have cutting oil on hand so I used vegetable oil. According to the internet, that used to be the main component of cutting oil. Go slow and make sure the tap is perpendicular to your hole. After each 1/4 turn I would back the tap out to clear the cut metal.
Step 5: Conclusion
I painted it in black and orange because orange is my favorite color. The wood 2x4 is a black rubber under coat and everything else is gloss orange. I left the surfaces that would contact the metal being bent unpainted as I figured it would just scuff the paint.
I would guess 1/16" steel and 1/8" aluminum is the most I could bend. I easily bent 1/16" aluminum.
The springs for the hold down make inserting metal very easy. The adjustability bolts also work as intended. Once I set those, I can butt the hold down against it and tighten the wing nuts.
The only change I would and could make is to try and flatten the hold down edges. The edges contacting the center plate have a slight radius. Grinding them down so they are flat against the base angle, while maintaining a flat and true edge would allow for a tighter radius. To grind them flat, I'd have to create some kind of jig to ensure the grinder is absolutely parallel to the angle.
Industrial metal benders have a curved tube on top of the hold down angle to ensure rigidity. I've got a little more than 38" between hold downs, which means I could get some flex. Until I experience the issue, I won' bother.
While I don't need a metal brake often, it's good to have when needed. Now I'm trying to come up with a project that requires metal!