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How to Buy String Trimmers

A string trimmer picks up where a lawn mower leaves off, providing the finishing touches as it whisks away grass around trees and flower beds, straightens uneven edges along driveways, and trims patches of lawn your mower or tractor can't reach. What's more, you can get a capable trimmer at a good price. Consumer Reports

Getting started - String trimmer guide
Electric string trimmers are finding more favor with environment-conscious consumers. But the latest gas-powered trimmers are polluting less than the older models, thanks to recently toughened California and federal regulations. Several premium gas-powered models certify that their engines will meet those regulations for 300 hours, rather than the usual 50. More hours mean not only less pollution, but possibly longer engine life. But those premium trimmers carry a premium price, about $200 and up.
Some electric plug-in models can provide fine trimming and edging for less money. But the top performers in our latest tests were still mostly gas-powered, and they remain our first choice for whacking the taller stuff and when an electrical outlet isn't nearby.

See how it feels
Handle the trimmer at the store to check its balance. After adjusting the front handle for a comfortable reach, hold the trimmer in the cutting position with both hands. Its weight should feel evenly distributed from top to bottom or slightly heavier at the top. Be sure that the controls work smoothly and are easy to reach.

Check the gap
Tall grass and weeds can slow or stall a trimmer by wrapping around the top of its cutting head, especially if there's a gap between it and the mounting for the grass-debris guard. Models with a small gap or a protective sleeve around the shaft avoided that problem in our tests and did well in tall grass.

Be safe
String trimmers can kick up debris. To avoid injury, wear safety glasses or goggles and long pants and boots. All but the cordless electric trimmers we tested emitted at least 85 decibels, the point at which we recommend ear protection.

Types of string trimmers
You don't have to invest in an expensive, professional-grade trimmer unless you need its metal-blade capability for cutting saplings and other woody waste. Most of the gas trimmers and even some electrics we tested can handle the grass and tall weeds that account for most trimming. Use this string trimmer guide to decide whether a gas-powered or electric trimmer fits your needs.

Gas-powered trimmers
Gas models are the best choice for trimming the tough stuff. These 9-to-14-pound machines are lighter than they used to be, but they're still two or three times as heavy as the corded electric models. The latest gas-powered trimmers run cleaner. but they still produce exhaust emissions. All require hearing protection.

Corded electric trimmers
These cost the least and weigh only about five pounds. They don't require tune-ups, and they start with pushbutton ease. They're lighter and quieter than the gas models, but the power cord limits your range, and you'll still need hearing protection with these models.

Cordless electric trimmers
Battery-powered string trimmers might seem like the best of both worlds: freedom from a cord without a gas model's fueling, fumes, and tune-ups. Cordless trimmers are also the quietest. But they tend to be expensive and heavy (about 10 pounds), especially considering their wimpy performance. And they run for only about 15 to 20 minutes before their battery needs recharging-which can take up to a day. Consider a cordless model only for the lightest-duty trimming.

String trimmer features
Even the best-kept lawn won't look its best with untrimmed walks and tall grass poking up around trees and fence posts. The latest string trimmers address lawn-grooming issues with more performance and convenience for less money. Here are the string trimmer features to consider.

Straight or curved shaft
The shaft transfers power from the engine or motor to the lines that do the cutting. Models with a straight shaft offer a longer reach, and they tend to be better for tall users and for reaching beneath bushes and other shrubs. Models with curved shaft teand to be lighter and easier to handle.

Split shaft
In these models, the shaft comes apart to accept a leaf blower, edging blade, or other yard tools. Most such add-on tools didn't prove to be very effective in our tests.

Rotating head
On some models, the head can be swiveled to a vertical position for edging.

Cutting line
Most manufacturers tell you which size replacement line fits your trimmer. Line that's too thin can compromise cutting power, while line that's too thick can bog down a trimmer's engine or motor. Two lines cut more than one with each revolution and can handle heavier growth.

Bump-feed line advance
This feature conveniently releases line from a spool when you bump the trimmer head on the ground.

Fixed-head lines
Instead of a spool, more consumer trimmers are using pro-style fixed strips to help eliminate jams and tangles associated with loading new line. You simply thread in a piece at a time.

Carrying aid
Many heavy-duty models have a shoulder harness for easier handling.

Top-mounted motor
This configuration makes electric trimmers easier to handle.

Stop switch
This safety feature lets you stop the engine or motor quickly without moving your hands.

Engine type
Four-stroke gas engines tend to start more easily than two-stroke engines. And they pollute less, because they burn straight gasoline instead of a two-stroke's gas-and-oil mixture. But four-stroke trimmers are heavier than most two-stroke models. Most gas-powered trimmers run on 87-octane regular, though some brands with high engine compression recommend 89-octane fuel.

Centrifugal clutch
This feature allows a gas-powered trimmer to idle without spinning the line, That's safer and more convenient than when the line keeps turning. (Electric models don't spin unless you press a switch.)

Starting aids
Spring-assisted starting makes pulling the starter cord of a gas-powered trimmer easier, and a relatively foolproof sequence for pushing the fuel-primer bulb and engaging the choke delivers the proper fuel mixture to a cold engine for faster starts.

Exhaust deflector
Most gas trimmers have a deflector to aim hot exhaust gases rearward. That's important if you're left-handed.

Translucent fuel tank
On gas-powered models, you can see at a glance when the fuel is low.

Alkyd-based finishes
Most alkyd (oil based) products require cleaning with mineral spirits, though a few can be cleaned with water.

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