Shop Tricks and Tools
Expand your fabrication skillset with four practical shop techniques that improve accuracy, efficiency and metal shaping capabilities.
Flame Shrinking
Most people who work with metal have used an oxy-fuel torch at some point to heat a stubborn bolt, bend a piece of metal or cut and weld something together. A torch can also be used for another important purpose: preforming heat shrinks to reverse distortion in your welded parts. Heat shrinking is a process of strategically heating a small area to counteract the shrinking caused by welding. The size and placement of the shrink depends mostly on the thickness of the material and where it is welded. We place the shrinks on the opposite side of the materials directly across from the welded areas to counteract the pull forces from welding. In the example, the flat bar has been distorted from welding the tabs on one side. The shrinking forces of the welds have pulled the material into a bowed shape, and it need to be flattened. This is where heat shrinking is helpful. The key to heat shrinking is to use a small flame (not rosebud or multi-flame tip) to heat a small area – usually dimeor quarter-sized – until the metal turns red hot. As the heated area cools, it creates pulling (shrinking) forces in the opposite direction of the weld’s pulling forces. When this technique is done correctly, you can actually see the material pull back into place. With a little practice and understanding, flame shrinking can be a great help when trying to fi x distorted parts.
Using TIG Filler in a Different Way
Making sure something is straight when fabricating is easily done with levels, fixtures, clamps and squares, but how do you make something straight that is initially curved or rounded? This is an easy trick I learned many years ago. A pieces of TIG filler rod can be a very effective gauge tool on curved surfaces. TIG filler is very consistent in length and diameter. It holds its shape very well when it is bent. By using a piece of 1/8-inch or 3/32-inch filler, we can make quick and accurate patterns, create smooth and accurate curves for layout, and use it to check highs and lows in a curved or rounded panel. Filler can also be a very effective tool in finding high and low spots in a curved or round panel like a fender of an older car a round tube. Filler can also be easily tacked together to create all kinds of patterns for making parts. It is one of the simplest and most effective methods in your shop for laying out rounded or curved lines, checking for low spots, holding parts in place for mock up, or making a metal realistic pattern of a simple part. With a little creativity and some practice, TIG filler rod can be a fast accurate and effective tool to make your curved parts straight.
Customized C-Clamp
C-clamps are probably one of the most common tools in any shop. They’re available in all sizes and shapes, but sometimes they’re just too small and we need a much larger throat depth to get the job done. The ability to clamp parts wen fabricating is critical, but being able to push or expand parts away from each other can be very helpful to. There are many ways to construct a custom push/pull C-clamp. Yours can be modified to you needs, but the clamp shown here can be a very helpful tool for getting things in place. We start by cutting the C-clamp in half and drilling holes for adjustability. When the two halves are drilled, the same distance holes are drilled into a piece of angle at whatever length you need. The two halves of the clamp are bolted to the angle at a distance you require for bar type clamping techniques. Pushing things away from each other simply requires the clamps to be unbolted and turned around. Having a long clamp or the ability to push things apart is a very useful tool for your toolbox. Each application will be a little different, but creating an adjustable deep-throat clamping device that can apply pushing and pulling forces is worth sacrificing the old C-clamp that’s been sitting around your shop.
Simple Hammer Form
Hammer forms have been used to create parts in the automotive and aerospace industries for decades. A hammer form is exactly what it sounds like: we create a form and hammer the metal into the form to give the metal a desired shape. Hammer forms such as this one can be easily constructed or can become extremely complex and intricate, but they are generally used for shaping thin materials – usually 16-gauge and thinner. This example was constructed to produce metal bowls for different applications, and can certainly be modified to your needs. The process and theory are the same for all hammer forms. We started with four layers of plywood with a 6-inch hole cut into each piece. The number of layers will depend on how deep you need the form. All pieces are screwed together to hold tolerance. A plastic or metal bowl will help you achieve the desired shape. Place the bowl in one end of the 6-inch holes and spray with a lubricant. Fill the form from the other side with fiberglass-reinforced automotive plastic filler. Once the filler is cured and the bowl is removed, the form is ready. Place sheet metal over the form, hold it in place with the top layer of the form, and screw it together to avoid any movement with the metal. Hammer the material into the form with a plastic or metal hammer to create the exact shape of the bowl used to create the form. Simple hammer forms can produce very smooth and consistent parts that otherwise would be difficult to make.