string trimmer

A string trimmer cuts grass and light vegetation by rotating a thin nylon filament at high speed, typically 3000 to 8000 revolutions per minute. The operator holds the shaft and guides the spinning line along edges, fence lines, and around obstacles where a mower cannot reach. As the line strikes vegetation, centrifugal force keeps it taut and the abrasive impact severs stems cleanly.

The monofilament line comes in several gauges, commonly 0.065 to 0.130 inches in diameter depending on the machine and the material being cut. Thicker line handles woody growth and dense weeds; thinner line suits grass and soft borders. The line automatically advances as it wears down, fed from a spool inside the trimmer head, and can be replaced when exhausted. Some machines use dual lines that rotate in a cutting head, others single lines.

String trimmers power either from electric motors (corded or battery-powered lithium-ion) or small gasoline engines. Corded electric units suit residential yards with convenient outlets; battery models offer cordlessness and silence, though runtime is limited to 30 to 60 minutes. Gasoline trimmers deliver more power and runtime but require fuel mixing, spark plug maintenance, and produce exhaust and noise. Professional landscapers favour gasoline or high-capacity battery models for extended jobs.

What goes wrong

The monofilament snaps or frays under hard use, reducing cutting efficiency and requiring frequent replacement. The automatic feed mechanism jams when line wraps around the spool incorrectly or debris enters the head. Thicker lines can break at the feed hole if the spool turns too forcefully. Bent shaft guards reduce cutting width and cause vibration. On gasoline models, fuel gums the carburetor if the machine sits unused for weeks, especially with ethanol-blended gasoline.

The term string trimmer describes the filament cutting method; it is also called an edge trimmer, weed whacker, or line trimmer in different regions. The equipment sits between broad-area lawn mowers and detail hand tools like shears, filling the role of perimeter finishing and spot clearing. In professional groundscare, a string trimmer is essential after mowing to edge walks, cut around trees and fence posts, and blend mowed areas into landscape features.