Bending metal is always a pain if you don't have the right tools. But luckily I happen to have a neat cheat to bend metal without the right tools. This is a cheat I have wanted to write an Instructable about for quite some time to add to my Shop Cheat series. But I hadn't had a project to demonstrate the Welder's Brake until now!
Here's the problem. I want to bend a piece of steel, but it is too heavy for my sheet metal brake. It has a maximum capacity of 18 gauge steel and this stuff is 14 gauge steel. Which shouldn't be a problem any more since I built my own DIY Press Brake. But the piece of steel is too big to fit in my press, even when I fudge it. Which effectively leaves me without the "correct" tooling.
Step 1: Overview
Incorrect or insufficient tooling is the perfect place for a Shop Cheat. This is something my Dad taught me and he always called it the Welder's Brake. Essentially the metal is scored by cutting something like a dotted line into it. The theory here is that instead of bending the whole piece of metal you instead remove metal so there is less metal to be bent. And once the bend has been made you replace the removed metal with weld fill.
The simplified explanation is cut, bend, weld.
Step 2: Cut
Everyone has heard the saying: "Measure twice cut once". I know I have written it into at least one of my other Instructables. But it is a good habit to get into. Before cutting I layout where the cut needs to happen. Then I further measure how I want to break up the cut into multiple smaller cuts.
A plasma cutter works pretty slick here. Since I need to start and stop my cut I really don't have a lot of other options. I could use a cut-off wheel, but it would take longer and may not be as straight. When using a plasma cutter on straight lines I always try to use some sort of straight edge. That way the line is straight. Because if this line is crooked or curved so will the piece I am bending. Which in this particular instance isn't a deal breaker. It's just nice to make thinks square and straight.
This is also where the safety disclaimer will show up. These interrupted lines mean I have to start cutting in the middle of the piece of metal. On light sheet metal like this it isn't too big a deal. But starting a cut in the middle of the metal will send sparks flying right back at the torch. If you're wearing your safety glasses and proper welding clothes you'll be just fine.
Step 3: Bend
Now that the line is scored it's time to bend the metal. I could try to do it entirely by hand but it would probably end up really wavy. It would be best if I had some sort of straight and rigid clamp that could hold the the metal while I bend it. Luckily my sheet metal brake can be used as a clamp. Otherwise I would have to rig something up with some angle iron on the edge of my welding table.
The metal will have to be properly aligned in the clamp. Which is really easy since there's a distinct line right where I want the bend. Once the clamp is tight it's time to start bending. Because I don't want to hurt my tool I will be bending the metal with my hands. Slow and steady is the way to win this race. If you try to bend too much too quickly you can over-bend the metal. And if you are using the hand bending route you could make things worse by bending the metal unevenly.
Step 4: Weld
With the bending done it's time to weld the metal where I cut it. This is pretty straight forward. But because of the width of the cut compared to the thickness of the metal, I have decided to add a little bit of metal to the seam. This extra bit of metal will help to fill the gap faster without heating the metal more than I want. So I'll just cut a piece of welding rod to the length and use it to fill the gap.
When welding I like to weld in small steps in an attempt to manage heat from welding. This is important because the heat from welding will distort and draw the metal in directions I may not be able to control. Ultimately these heat distortions could ruin whatever I'm welding, even big beefy bits of metal are susceptible to this.
In this particular case I will be welding about an inch and a half or less at a time. Laying one bead then moving on to the next seam in a leapfrogging pattern. After every step is made across the whole piece I take a little break to let the metal cool down a bit then resume the work. Working like this does eat up a lot of time but the results are hard to argue with.
After the welding is done I could stop and move on to finishing steps like painting but I want it to be a showy shiny part. And I have not been careful enough to make pretty welds. Which is nothing a little time with a grinder can't fix. After that I can move on to paint and finish.
All in all this project didn't turn out half bad. In fact I'm quite happy with the results.
Step 5: Missteps and Mistakes
Unfortunately there are limitations to this technique. Up to a certain thickness of steel, and presumably other metals, it becomes increasingly difficult to successfully use the Welder's Brake. I tried it on an earlier project and found that I would have been better off using separate pieces of steel rather than all one piece.
This attempt was made using 1/4 inch steel. After having to make multiple cuts because the steel was too rigid even when nearly severed. And once it did yield it cracked so badly that I had essentially cut the metal and welded it back together. Needless to say I was very disappointed with the results. But with any luck you can learn from my mistakes.