How-To Guide for Safely Manipulating and Repairing Sheet Metal

The practicality of sheet metal is greatly enhanced once one knows how to manipulate it into shapes that help to serve your function. However, special precautions and methods are involved in the shaping process. Carelessness or lack of know-how can damage or destroy the expensive sheet metal. This article will describe how to bend, anneal, reinforce lip, and fold sheet metals such as aluminum, brass, copper, iron, tip, or zinc.

There are only a few tools that will be needed for manipulating sheet metal, none of them that would be considered specialized. In fact, you will find most, if not all, of the tools already in your home shop. It should also be noted that sheet metal is defined as being no more than 3/16-inch in thickness.

BENDING SHEET METAL

Sheet metal can be bent by hand using anything that will give it solid support on both sides throughout its entire length. Bending the metal lengthwise will require a bench top, thick hardwood boards, clamps, or a vise. A hand vise will usually be ample enough to support a short bend. Bending the metal using a rubber mallet will result in significantly less surface area damage than a hammer. Rubber can cover the hammer’s metal head if the appropriate mallet is not in your arsenal of tools.

Softer metals are very flexible and can be easily manipulated by simply hammering it out to the desired shape and size over the surfaces previously noted. Placing sheet metal in a vice or clamp with shaped wood blocks will create a compound curve. Clamps will also allow you to create sharp angles by hammering the exposed sheet metal over the block. Uneven clamp blocks with a curved surface will allow you to create smooth angles in the sheet metal.

Metal that has been extensively hammered can become hard, rigid, and difficult to manage. The only way the malleability of the metal can be restored is through a process known as annealing. Annealing is the heating of metal to its critical point and then allowing it to cool. Once this process has been performed, the softened metal is once again flexible and you will be able to continue hammering it into your desired shape.

REPAIRING SHEET METAL

Minor dents in sheet metal stretch the material so it therefore must be shrunk back to normal size for it to be repaired. The dented sheet metal will have a concave side and a side that is convex. If the convex part of the dent is accessible, hammer the metal back down using a rubber mallet. To reduce further damage to the metal while hammering, place the sheet against a soft and sturdy surface, such as a large sandbag. If the convex side of the dent is obstructed and cannot be reached with your hands, a wood stake or a metal bar can be used. Press one end of the stake or bar against the dent and lightly hammer the other end. This will usually cause enough pressure and vibration to remove the dent.

SAFETY WITH SHEET METAL

Safety is an important issue when working with sheet metal. The edges of the metal can be very sharp and should therefore be eliminated. Folding the metal at its edges will create a single hem that is also a safe surface. Scoring a line that is parallel to the edge of the metal and is 3/8 of an inch inwards is the first step in creating this hem. Place the sheet metal in a clamp with the scored line outside of the block. Hammer the edge down so that it is perpendicular to the sheet and remove. Place a piece of scrap wood up against the inside 90 degree angle of the metal. Hammer down the metal so that the scored tab is parallel again to the sheet. Remove the piece of scrap and then bend the edge down until it meets the metal surface. This will give you a smooth edge that is not very noticeable, serves as reinforcement, and eliminates any safety hazards.