A lot of the complicated shapes that are needed in siding and roofing can be crafted with a combination of simple shapes and bends. This video shows the formulas for four simple bends
Hemming an edge on a Tapco sheet metal brake
Use the front edge of the brake as a measuring tool. It is set back from the clamping edge 3/4-inch. Fold the edge all the way around, so that the metal is nearly bent flat. Remove the workpiece and clamp the brake again. Place the bent edge against the clamp, lift up on the hinge, and finish the bend to tighten the fold. This yields a smooth factory-looking hem.
How to bend a sill seam
- Slide the hemmed workpiece back into the open brake to the edge of the initial bend and fold over.
- Hem again by lifting up on the hinge, and tightening the seam.
This seam can be used to hide the edge of another piece of sheet metal, for siding, window trim, or otherwise. Sill trim can eliminate the need for face nails in many applications.
How to bend a simple step-bend or z-flashing
The default offset between the bending edge and the clamping hinge is 3/4-inch, so a 3/4-inch Z-flashing is very simple to make. This is handy because a lot of exterior trim is 3/4-inch thick.
Step 1: Bend 90-degreesStep 2: Flip the sheet metal over and bend another 90-degree bend
The formula for bending sheet metal with a 1/2-inch step
Because the default offset between the bending edge and the clamping hinge is 3/4-inch, many people do not know that you can smaller Z-flashing sizes. In fact, you can make 1/2-inch Z-flashing or even 3/8-inch Z-flashing by splitting the first 90-degree bend into two parts.
Make a 45-degree bendFlip over sheet metal, make the second 90-degree bendFlip over the sheet metal again, and finish the 45-degree bend into a 90-degree bend
Step-bends are an integral part of many profiles needed for roofing and siding installation and replacement. Now you know that you have more formulas for bending sheet metal
