Metal Bending Tool
November 2013
I needed to make metal landing gear fittings for my Bower’s Flybaby. The fittings are made from .093” 4130 sheet bent into a U-shape with a 1” diameter. I couldn’t find .093” sheet steel, so I went with .1”. Bower’s suggests tack welding the sheet steel to a 1” pipe, then using a torch to heat the metal until it’s pliable. I tried this, but couldn’t get enough heat with my crappy torch setup. I tried bending the metal by beating it with a mallet around a hardwood form. This sort of worked, but it was really hard to get a good shaped U. Out of 4 attempts, I only had one good piece.
What I needed was a proper metal bending tool. I shopped around but commercial ones that could handle a 4” wide sheet of steel were very expensive. They looked pretty simple, so I decided to try building my own. It turned out OK.
The rails are 1.5” x .2” inch hot rolled steel. I purchased two 4’ bars, and cut them into a 30” and 18” pieces.
The center form/die is a ¾” bolt with 1” steel bearings/spacers around it.
Two ½” bolts apply bending forces evenly to the sheet metal.
I purchased a variety of bolt sizes, but I think 7” is mostly what you need.
The spacers at each end of the bending tool are perforated rectangular tubing. These cam in 3 foot lengths and were 1.5 inches wide, which meant 3 sections would make a nice 4.5” wide spacing between the rails. Wide enough for the flybaby fittings. In hindsight, these didn’t have to be metal. Wood would have been cheaper and easier to work with.
All materials were purchased at my local Lowes home improvement store.
Tools used to construct the bender include a grinder, metal band saw (hack saw would be fine, you only make a few cuts), and drill press.
Total cost was just under $90 for materials.
In the above photo, you can see that the short 18” arm is bolted to the table, and the longer 30” arm swings freely.
The above photo shows a piece scrap metal being bent. The 30” lever easily bends .1” 4130 chromoly sheet steel
I think it’s best to bend a rectangular piece of oversized metal then cut the final fitting shape from it. It’s pretty hard to bend a precut piece and ensure the bend happens right at the center. Your shape will more likely come out lopsided.
Also, the bending process expands the metal almost 1/8” across the top surface. Adjust the pieces you cut out appropriately.
There’s very little spring back, but a couple pieces did come out about 1/16” too wide. I just put them into my vise and squeezed them down to the final 1” wide U-channel.