Working with sheet metal is a skill that many types of professionals, from fabricators to roofers, need to master. Others can develop a basic understanding of how to complete sheet metal projects on their own, saving money and opening the door to creative projects or quick repairs at home or on the job. Prior to employing sheet metal fabrication techniques, workers need to go through a careful and accurate layout process.
Plans and Measuring
The first step in a sheet metal project layout is creating a schematic, or a drawing on paper that includes diagrams and measurements. One of the first decisions you need to make is your measurement system, namely whether you'll work with English or metric measurements. The tools you have access to and the other components of the job will likely make one system more useful than the other. Make sure you understand the blueprint or schematic fully before you move on to more advanced computations.
Based on the thickness of the sheet metal you're working with, and the nature of the schematics you're working from, you'll need to perform a series of basic layout computations to complete the schematic and prepare to mark your material. Bending formulas, which are available in shop manuals and online, calculate the amount of material you must allow for a bend given the thickness of the sheet metal and the radius of a bend. Other computations are matters of simple arithmetic. In each case, double check your work to avoid costly mistakes down the line.
Sheet metal workers use a number of different tools during the layout process. The general purpose of these tools is to measure and mark the metal in accordance with plans on paper. This will greatly improve the chances of accurate fabrication and precision work. Common layout tools such as scratch awls, punches and scribers allow you to score sheet metal to indicate the appropriate places for cuts, bends and breaks. Protractors and steel squares provide the straight and curved edges you will outline with marking tools, allowing you to transfer a layout from a schematic to your sheet metal.
For projects that require you to produce a large number of identical sheet metal forms in repetition, a template will help you reproduce the layout more quickly. A template may take the form of a full-size paper schematic with small holes to indicate where punches and scores should appear on your metal. By overlaying the template, you can use a punch to produce small marks on the sheet metal with a punch and ball peen hammer, later connecting the dots with a scratch awl and steel square. This eliminates the need to measure every mark, although it also increases the importance of having an accurate template to start.