String trimmers are one of the more basic lawn tools for keeping-up a lawn well manicured or cutting back weeds and light brush from around poles, fences, buildings and what have you. Before the advent of the string trimmer, which came about in the early 1970's, the most effective way to trim grass and weeds were by using glorified hand-operated scissor trimmers. String trimmers literally revolutionized grass trimming overnight, and it is hard to believe there actually was a time when string trimmers didn’t exist.
Modern string trimmers are either gasoline powered by using a 2-cycle or 4-cycle power plant, or electrically powered through either a corded or battery pack. For a detailed description of what power plant is right for you, please see our lawn equipment power source buyer's guide.
String Trimmer Types
Curved Shaft
Curved shaft trimmers are the most ergonomically correct, and therefore the most comfortable to use. The shaft near the head curves downward so you can literally stand straight and upright while trimming tall grass and weeds. This orientation allows for longer string trimming without fatigue, and these trimmers are specifically targeted towards the weekend warrior homeowner.
With these models, manufacturers must use a flexible drive shaft from the motor down to the trimmer head. Although this makes it easier to trim, only light duty accessories (or none at all) are recommended. Accessories may put more strain on the drive shaft and cause premature failure than what the original equipment intended. Many accessories will void the original warranty entirely, so curved shaft trimmers are best used as is from the factory for the purpose of trimming weeds or high grass.
Straight Shaft
Straight shaft trimmers are heavy-duty types, and accessories like larger trimming heads, blade attachments, and various other accessories can be used. Straight shaft trimmers come equipped with more powerful engines, because the shaft can handle more torque and horsepower without becoming damaged.
Some are literally equipped with bicycle-style handles and shoulder straps to distribute the weight evenly while allowing maximum control when cutting. These types of string trimmers are the heaviest and most powerful of them all, intended for heavy-duty jobs.
Although not as ergonomically friendly as curved shaft trimmers (and therefore not as suitable for extended trimming chores) they make up for this through their versatility. These trimmers allow greater reach under patio decks, bushes, and overhanging trees or shrubs; trimming weeds in these instances will be easier than using a curved shaft trimmer.
Straight shaft trimmers are also able to utilize accessories such as cutting blades which gives you the flexibility to slice through tougher weeds, like thistle or goldenrod, and you can even trim small branches on trees.
Split Shaft Trimmers
The “split shaft” is a term that means the shaft splits in two via a locking mechanism. These trimmers are made to be outfitted with special manufacturer made accessories. The lower shaft can be replaced with such things as cutting heads, blowers, tree trimming heads, edger blades and a host of other accessories. This makes them the most versatile trimmers available, but each add-on accessory may cost as much as the trimmer itself in some cases.
Trimmer Head Features
Manual or Automatic Feed
As you trim, the trimming line will slowly degrade and shorten as you hit solid objects like tree trunks, buildings, and fences. To keep you trimming and on the move, manufacturers have designed two trimmer heads; manual line advance or automatic line advance.
Manual Advance
Generally, lower priced trimmers come with a manual advance feature, and higher priced models offer an automatic line advance. The most common type (and the least expensive) is a manually activated bump button on the bottom of the head.
The bump button allows you to firmly bump the bottom of the trimmer head onto a hard surface which will let out a few inches of trimmer line from the head. The safety (which virtually every trimmer comes equipped with) has a small blade attached on the underside that will automatically trim the line to the optimum cutting length, each time you “bump”.
Although effective and efficient since you control how much line to let out each time you bump, you may have to shut down the trimmer and re-thread the trimmer head spool if you forget to advance the line or it gets cut too short by whipping into a solid object.
Automatic Line Advance
Automatic line feeding attempts to do away with human error by advancing the line automatically when it gets too short. As the line degrades, the head spins faster and that triggers the line to automatically advance. In essence, this should keep the line at roughly the same length at all times making it easier for you to keep on trimming continuously. However, because it is almost constantly advancing the line, you will go through more trimmer line than using a manual advance.
Single or Multiple Trimmer Lines
Single trimmer lines are generally supplied on the least powerful trimmers, and many electric trimmers are outfitted with single trimmer line heads.
Single Lines
Single lines offer the most efficient use, because only one line will degrade at a time. You'll lose less trimmer line, and therefore less downtime, re-spooling a single trimmer line. In virtually all cases, single trimmer line heads are made for light duty trimming. Basic weed trimming on city lots would be an ideal place for single line trimmers. Nothing heavy duty here, just effective weed trimming around your house or home.
Multiple Lines
Multiple line trimmers consist of two or more trimmer lines coming from one head. This allows one rotation of the trimming head to cut and slice two to four more times in one pass. These heads work better on heavier weeds and when used as basic edgers around sidewalks and porches. However, more lines means more line degradation, and that comes with a price. Although this is certainly a better set-up for larger and heavier tasks, you'll also be changing the line more often as well.
What's Best for You
Generally, where you live and the type of trimming you need to be done will determine what kind of trimmer is best for you.
City Living
Most city lots only need weeds trimmed from around sidewalks, porches and trees. Any basic smaller type of weed trimmer will work, particularly curved shaft models. Electric trimmers, either corded or battery operated, would be an ideal choice, because space is limited and cord length would not be an issue. The least powerful single line trimmers would be adequate for virtually any city trimming task, and the least expensive of all weed trimmers are the corded electrical models.
Suburban Living
Most single line trimmers would make a good account for themselves in this setting, but if you need a bit more mojo for tougher weeds, a multiple line trimmer would be your best bet. If you only plan on doing trimming chores, a curved shaft trimmer would be ideal. But if you have a little space out back that gets overgrown from time to time, the flexibility and the added power of a straight shaft trimmer would be a better bet.
For even more versatility, opt for a split shaft trimmer. You'll be able to convert this unit into many other yard tools, from blower to edger and everything in between, and instead of cluttering up your garage or shed with a host of different types of powered lawn tools, you can standardize your lawn appliances by using a split shaft trimmer for maximum versatility.
Country Living
Depending upon the type of country living you do, be it a home on several acres, a gentleman's farm, full-fledged cattle farm, or a commercial vegetable growing operation, you may opt for several different types of trimmers.
A big straight shaft high-horsepower unit would be perfect for cutting tough weeds in the back 40, while an electric single line trimmer (either corded or battery powered) might be perfect for around the house or the homestead. A lighter weight straight shaft trimmer would allow you versatility around the barn or other out buildings, with the ability to change out to different heads as needed for the type of work you may encounter.