Types of string trimmers

String trimmers use electric motors or gasoline or propane engines to rotate one or two thin nylon lines with such speed and force that they can cut grass and weeds. Also called grass trimmers, line trimmers or weed eaters, these tools make trimming and edging a lawn much faster and easier than using hand tools like grass shears. The best string trimmers can handle tough weeds and tall grass along fences and keep a long driveway trimmed. String trimmers can also reach under shrubbery and cut grass in places too narrow for a lawn mower to reach.

There are three main types of string trimmers, each with advantages and drawbacks.

  • Electric string trimmers: Corded trimmers are quiet, and heavy-duty models can power through tough weeds. But you're restricted by the length of an electrical cord (usually 100 feet). If you need to trim grass and can finish your trimming in less than an hour, a cordless electric trimmer is an option. Both types are quiet and are the least polluting type of trimmer.
  • Gas trimmers: For big lawns or for cutting tough weeds and tall grass, gas-powered string trimmers are more powerful than electric models. You aren't limited by a cord, but you do need to buy and store gasoline. Four-stroke models are more efficient, and you don't have to mix gas and oil as you do with two-stroke models. Four-stroke models are also quieter and vibrate less than two-stroke engines. However, two-stroke models are lighter and require less maintenance.
  • Propane string trimmers: Propane trimmers can be as powerful as gas trimmers, but they use 16.4-ounce propane canisters for fuel. The upside is that propane is far less polluting than gas. The downside is that the canisters, which cost between $2 and $5 each, only give you two hours of run time and can't be refilled. However, empty canisters can be recycled.

Differences in shaft types

String trimmers come in three basic shaft designs: straight, curved and split-shaft. It's a matter of personal preference which one you prefer. Professional landscapers tend toward straight trimmers. Tall users are also more apt to find straight-shaft trimmers comfortable. Many trimmers come are available with either type of shaft. Split-shaft trimmers are the most versatile, since you can remove the string-trimmer head and attach a variety of other accessory tools, such as a leaf blower or edger.

Important features

Experts offer the following advice for buying a string trimmer:

  • Gas, propane or electric? For trimming grass, experts say budget electric trimmers are fine. Cordless trimmers are convenient, but only run about 20 minutes per battery charge. If you need to whack tall grass or weeds, you'll need a more powerful corded electric trimmer or a gas or propane model. Electric and propane trimmers are more eco-friendly than gas trimmers.
  • Good balance is just as important as weight. Make sure the string trimmer's weight is evenly distributed. Trimmers with an electric motor at the bottom of the shaft are less balanced than those with top-mounted motors.
  • Some trimmers can take attachments. Many string trimmers can double as edgers or accept attachments such as metal blades for cutting heavy brush. For edging, reviewers like trimmers with rotating heads that flip over so you can still hold the handle in a comfortable position.
  • Fixed-head and bump-feed trimmers are more convenient than automatic string feeds. Fixed-head trimmers use line in small precut lengths instead of unwinding it gradually from a spool. Owners say it only takes seconds to insert a new piece, though some prefer bump-feed line advancement. Automatic string feeds are fine when they work, and reviewers say they're often better than bump-feed systems that feed out more line when you tap the trimmer's head on the ground. If you do choose a trimmer that feeds line from a spool, look for one that makes it easy to replace the spool instead of one that requires hand winding and disassembly.
  • Spring-assisted starting is a plus for gas string trimmers. This makes it easier to pull the starter cord.
  • If a gas trimmer has a translucent fuel tank, it's easy to know when it needs refueling.
  • A shoulder strap or harness makes for comfort and back safety. This is especially applicable for heavy gas trimmers.
  • Left-handed users need rear exhaust. Not all trimmers have a deflector that can send the exhaust to the rear instead of to the side, where it will hit left-handed users.

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