I read an interesting instructable about a metal bender and then I saw the most interesting photo of a theatrical workshop tool. I formulated an idea and it quickly turned into a new tool.
Step 1: Preparing the Vice
I am only planning to bend aluminum and galvanized steel wire so I don't need a hydraulic jack and I know that drill press vices can be had for about $20. I decided to go get one and look for a roller of some kind at the same time. I ended up using a marine rubber roller. I assume they are used for ropes. It is hard rubber about 12in long and 2 inch in diameter with a 3/4in hole in the center. I figured it was about perfect to put a roller from a laser printer in the center.
The drill press vice comes with a puny piece of steel holding down the floating jaw. In my case I need a lower support for my roller so I needed to upgrade it. I found an old clamp piece from a bed frame that I had saved. It was solid and fit the bill nicely. In addition to the rollers I also had some brass bushings and plastic bearings. I used a short piece of aluminum track and a little UHMW plastic to house the bushings. At the end I drilled down through my new hold-down plate. This will take all the forward thrust when I tighten the roller on the workpiece. Essentially this pushes the upper bearing back against the floating jaw.
If you don't have that I suggest you use an angle iron on the jaw like the original picture and then drill down through both to support your roller. A vice and a step drill bit make this operation a lot easier. A drill press is best but a vice is essential when drilling metal. Never attempt to drill metal without one.
Step 2: Let's Get Rolling
I cut a 2-1/2 inch piece off of the rubber roller using a band-saw. It cut very nicely and I'm sure it could have been done with a hack-saw. The rubber on the printer roller fit tightly inside the rubber. I tried to bend the roller to make a crank in the vice but realized I didn't have the strength so I cut it off and attached a wheel instead.
Next I took two bed frame casters, added some electrical tape to make them bigger on the edges as opposed to narrower on the edge as they first appeared. I found some steel plates that seemed to be appropriate but could just as easily have used some angle iron. The 2x10 is added for a sturdy support. All the weight of the bender will push against it so I wanted to be sure it was solid. These plates ensured that the casters would not rotate. An added bonus that can be achieved by simply adding screws on either side of the brass frame of the caster. Drill into the wood where it seems like the center wheel has enough room to come right up in between.
I attached the caster frame to the jaw by drilling out the hole and removing the screws that hold the jaw. I saved the jaw for later and screwed it all down to a 2x10 piece I had laying around.
Step 3: Let's See It in Action
I'm bending an 8 foot piece into a circle 2.5 feet in diameter. I tried it on the floor but realized I would have troubles. I decided to mount it on the fence. It was a good choice. While running the piece back and forth I noticed that the rubber wheel wormed itself away from the shaft when I fed the piece in from the left. If I fed from the right there was no problem. The rubber around the printer roller is being slowly destroyed while I operate but it's not so fast that I can't fix it. I'm thinking about silicon caulking.
It works like a charm and I will definitely be keep it around for bending jobs like this one. The best I could do by hand pales in comparison to what comes out of this thing. Once I figured where I wanted to set the roller I marked it. I loosened off and got the flat stock in there, reset the jaw and it curled up perfectly first roll through. The aluminum is work hardened and retains the curve well.