Some grass trimmers have a plant guard, which is a wire hoop that projects in front of the grass trimmers. Remember to keep this up against the tree or bush, and be aware that if you swipe sideways you will cut into the bark. Use a trimmer with one line - a trimmer with one line is generally easier to thread than a trimmer with two.

Start by adjusting your grass trimmer so you can comfortably hold and control it when cutting a vertical edge. If you've got a lot of trimming to do, it's easy to put stresses and strains on your body, so avoid this by swinging the grass trimmer only as far as is comfortable. Keep plenty of line on the trimmer head - don't worry that your line is too long. The trimmer head has a blade that will cut off any excess so it's the optimum length. Use the manual-release button - if the trimmer isn't pushing out more line automatically, it could be that the cord is slightly tangled up inside; the manual-release button means you can pull more line out past the problem.Please note: all dimensions indicated in this ad are approximate and may vary slightly from indicated measurements. They are included as a guideline to assist you in selecting the right part for your machine** It's very easy to accidentally catch the base of trees and shrubs with your grass trimmer, which rips the bark, letting disease into the plant. In the worst cases it's possible to kill a tree if the bark is cut right around the trunk. Remember to feed out plenty of line when you're doing this. The line will break regularly and there's a risk that you will lose it if you don't feed out more regularly. You will also work more efficiently by using the maximum cutting area.

On some newer trimmers, you don’t even take the cap off. You just pull out the old line and feed a new one into it (Ryobi in particular seems fond of this design). Swing it from side to side, cutting in one direction only. This will push all the debris in the same direction, making it easier to see where you have cut, and to clear up afterwards. Rotate the head to cut vertically and adjust the shaft length if necessary, as well as the position of the handles.Dimensions: Spool Cover Width: 85mm, Spool Cover Height: 35mm, Spool Width: 65mm, Spool Height: 20mm, Spool Inner Diameter 16mm