Molten magnesium alloy is forced at high pressure into steel dies, making the two halves of the crankcase. The process holds tight dimensions and allows thin walls, which cuts weight.

Cylinders with cooling fins, pistons and other aluminum or magnesium parts are cast for a single-cylinder two-stroke engine. Some saws now use a magnesium piston.

Castings are machined where the crankshaft, piston and cylinder must fit within tight tolerances. Magnesium cuts easily, which keeps this step fast.

The cover that shields the cylinder and muffler is molded from fiber-reinforced plastic, strong yet light.

Wear-resistant alloy steel becomes a long bar with a rounded nose and a slot around its edge to guide the chain. Professional bars are solid steel with a replaceable nose, and consumer bars are laminated with a small nose sprocket to tame kickback.

Specialized machines punch side plates, drive links and teeth, then rivet them into a loop. Each tooth is a folded tab of chromium-plated steel with two beveled edges, and left and right teeth alternate.

Crankshaft and piston go into the crankcase along with the carburetor, the oil pump that feeds the bar, and a centrifugal clutch with its sprocket drum. Springs or rubber mounts decouple the handles from the engine, much like a car's suspension.

The bar bolts on under the clutch cover, the chain is tensioned, and the saw runs. At idle the clutch stays open so the chain sits still, and it only grabs as engine speed climbs.