Mechanical cutting tools use physical or abrasive force, often applied by hand, to achieve the desired effect. This would include tools such as hacksaws, shears, chisels, or metal grinders. The size of these tools can vary; smaller tools are easier to transport, but larger tools tend to have more cutting capacity.
Hacksaw – a fine-toothed saw designed specifically for metal cutting. Cutting capability is dependent on two things: blade material and the number of teeth per inch. A blade with more teeth per inch (e.g. 32 tpi) has finer teeth for cutting thinner metal, while a blade with fewer teeth per inch (e.g. 16 tpi) will have coarser teeth for cutting thicker metal such as pipe.
In addition to the thickness of the metal, you should also consider the type of metal to be cut. The general rule is that hard metal will require a blade with finer teeth, while a blade with coarser teeth will work fine for softer, malleable metal.
Reciprocating saw – a narrow but long saw that cuts with a reciprocating (back and forth) motion. The saws, commonly called “Sawzalls” after a popular brand name, are available in corded, cordless, and air-powered versions that resemble a drill. A cordless saw is obviously the more portable option; however it is also less powerful and will weigh more because of the required battery.
Circular saw – as the name implies, this is a saw with a round blade. When equipped with a special metal cutting blade, these saws can cut metal up to 25 mm (1”) in thickness with reasonable speed and excellent edge quality.
Shears – often called snips, these come in a range of styles; some with long handles and short blades, springs, offset handles, curved blades, etc. Electric- and air-powered versions are available. While extremely portable, shears are only able to cut thin, softer metal such as 16 gauge (1.709 mm or 0.0673") (or thinner) aluminum and steel.
Chisel – a long straight blade with a beveled edge used to cut wood, stone, and sheet metal. Air-powered chisels are available which provide a little more power. Still, metal use is normally reserved for instances when other methods are not feasible, as chisels tend to leave a rough finish.
Grinders – a corded, cordless, or air-powered (often called a zipsaw) tool with a round flat blade at the end used to grind or cut material, including metal. When used for cutting, the thicker grinding blade or wheel is removed and replaced with a thinner blade called a cutoff wheel.
There is no doubt that manual tools have many uses. They are extremely portable, small, and often self-powered. The drawback, however, is that these tools cut slowly and the resulting cut is usually somewhat crude. Because of that, the mechanical cutting tools are best limited to instances were minimal and occasional cutting is required.