Auto body hammers and dollies are an essential part of any auto tool kit where metal sheet work is required. They may look like simple tools but require a certain measure of skill if they are to be used in the proper way. You may find it easy to drive nails into a wall or wood with your regular hammer, however, this is not the case when it comes to lumpy metal. With an auto body hammer, it is possible to deliver accurate blows to the sheet metal. To begin with, it is necessary to become familiar with the various types of auto body hammers in order to learn how to use them properly.
Types of Body Hammers and Dollies
Auto body hammers are named after the shape of the head which is opposite the face. These include Chisel, Cross Peen, Pick, and Claw. The Pick hammer is used to raise low spots in metal finishing, while a Cross Peen or Cross Chisel are used to repair a damaged crevice or ridge. The face of an auto body hammer is usually round or oval-shaped with a curvature of approximately 1 ¼ inches to 2 inches. The curvature plays an important part in thinning and stretching the metal sheet. Lightweight auto body hammers of about 12 oz. are ideal for delicate work, while the hammers weighing 18 oz. or more are best suited for heavy collision repair. If you are looking for something durable, hammers with fiberglass handles are an ideal choice versus hammers with wooden handles. Dollies also come in various shapes, and the one you need depends on the nature of work you perform. For heavier sheet metal it is possible to use a heavier dolly.
There are two techniques of using an auto body hammer and dolly.
Hammer on Dolly Technique
In this technique, place the dolly precisely behind the affected area. With an auto body hammer, lightly tap the metal that is placed on the dolly. Care needs to be taken to tap lightly so the metal does not stretch beyond its limit. After a few taps, check to see if the dent still persists by running your hand over the area. If it persists, lightly pound the metal again until the dent disappears. While hammering, make sure you press up on the dolly with sufficient force. If you fail to apply adequate pressure, you may end up denting the sheet metal instead of smoothing it. The theory behind this is that the area being hammered moves up, while the surrounding metal stays where it was.
Hammer Off-Dolly Technique
It is recommended you master the hammer on dolly technique before trying this technique. In the hammer off-dolly technique, the metal needs to be placed a ½ inch away from the dolly. This will result in the metal being pushed in the opposite direction of the hammer. The dolly touches low spots on the metal as you continue to hammer on the high spots. This makes the high spots go down while the low spots move up with every rebounding action of the dolly. Make sure to keep close contact between the hammer and dolly for better rebound action.
A good idea is to practice with a sheet of junk metal in order to master both techniques. Starting with simple tools and then moving on to more powerful tools will help you master these techniques more quickly.