Bending jigs are used to shape sheet and strap iron, steel and other metals, usually without heating. Jigs assist in creating curves or folds to make pieces fit an opening or to create architectural elements such as gates, wall decor, business signs and logos or guards for security doors and windows. Make several smaller or larger jigs, depending on the thickness and width of the material to be bent.
Cut a 2-feet piece of 2- by 4-inch stock lumber for a small jig. Cut longer pieces for larger jigs.
Carve a two-handed handle onto one end with whatever tools you have available.
At the opposite end, drill two 1/8-inch diameter holes, 1/4-inch apart. To make larger jigs, drill larger-diameter holes placed 1/4-inch further apart than the original for every 1/8-inch in diameter used for the new holes.
Drive barn spikes or gutter nails into the holes with a hammer so that they go completely through the board and the heads are flush with the wood. If using larger-diameter holes, use matching-diameter round stock instead of gutter nails or barn spikes.
Cut the gutter nails or barn spikes to a 2-inch length on the other side of the board, using a hacksaw. Remove any burrs from the cut ends of the nails using a 24-grit wheel on a right-angle grinder. The finished jig should resemble the metal bending jig designed by David W. Wilson, described and illustrated at Tinbasher.com.
Place the metal to be bent between the nails and bend to shape. Normalize the metal after bending, using standard techniques of your choice, to prevent or reduce metal fatigue caused by the bending. "... (B)ending perpendicular to the rolling direction (of the sheet or strap metal) is easier than bending parallel to the rolling direction. Bending parallel to the rolling direction can often lead to fracture in hard materials ... (and) is not recommended for cold rolled steel > Rb 70, and no bending is acceptable for cold rolled steel > Rb 85," according to Engineering Fundamentals, known as eFunda.com.