How to Bend Sheet Metal

If you don’t have a special tool for bending sheet metal (called a “sheet metal brake”), you can also do it with a vise and your bare hands, provided that the metal isn’t too thick. Below, we’ve outlined the basic materials and steps needed to bend metal for your own hobbies.

  1. Buy the Right Materials: To do the job correctly, you’ll need a vise, two form blocks (wood or metal), a calculator, protractor, tape measure, mallet, and something to write with. Depending on the metal’s thickness, you may also need a heavy-duty hammer instead of a mallet.
  1. Assess the Metal: First, use your tape measure to figure out how thick the sheet metal is, and then plug that number into this formula: (π/180) x B x (IR + K x MT).

MT is the metal thickness, K is the K-Factor (find it with this chart), IR is the inside radius, and B is the desired bend angle. With the formula completed, you’ll find the bend allowance, which is precisely how many inches the metal will expand when bent.

  1. Get Ready to Bend: Before putting the sheet metal into a vise, first mark your bend lines with a pencil, and then cut the sheet so that at least ¼” of extra room is left over. Finally, make sure the sheet is filed down smoothly, because otherwise you may get cracks in the metal.
  1. Place Forms and Sheet in Vise: Your form blocks should have the exact shape for bending your metal angle. When you clamp the sheet metal into the vise’s grip, make sure the bend lines on your blocks and sheet match up. If there is too much play in the metal and it feels wobbly when you put pressure on it, you might want to ask a friend to hold the top while you use the mallet.
  1. Bend the Metal: Lastly, you should lightly tap the sheet with a soft mallet, going from one end of the bend line to the other. This way, you’ll avoid unsightly dents and ensure that your final bend is strong.