Originally Posted By: SOHCman
This is on a FS70, I even got some of the heaviest stihl brand trimmer string available, and it still breaks/grinds off about as easily as the thin stuff. And then when it breaks off even with the spool head, you have to shut down the trimmer and pull the head apart to feed the line out again.
Anyway, I want to get the best solution available. Does anyone use one of those heads that you clip the plastic blades onto? What about the ones you just poke new lengths of line into? I just want something that is tough and doesnt have to be taken apart to fix the line.
I use this on heavy weeds clearing, edging the driveway, trimming the fence, and against broken faced landscaping bricks.
The trimmer line is not breaking, it is melting! Do you notice that when you take the head apart to pull the line back out that it is kind of stuck together? It is MELTED together.
The solution to your problem is to BACK OFF from your work. Let the very tip of the trimmer line do the work. If you force it in too close, the line drags across your work and generates so much heat from friction that it melts. This is particularly true when the trimmer is used up against hard surfaces like cement, rock, brick, trees, and even dirt.
Also, as was previously mentioned, you don't need to run the engine at full throttle for all of your trimming. The faster the trimmer turns, the quicker the line will melt. However, there is one problem with doing this, you need to run the trimmer at a minimum of 1/2 throttle speed to fully engage the centrifugal clutch. If the clutch is not fully engaged it will slip, overheat, and wear out. ONLY use the size (diameter) of trimmer line that the manufacturer of your trimmer recommends, thicker line is NOT better!
Lastly, purchase a quality name brand trimmer line and no more of it than you will use up in one season. Trimmer line gets old and your problems will get much worse when it does. The best grade of plastic is MN7. If you can find a manufacturer that specifies this grade of plastic, use it. If you can find it, round trimmer line is the most resistant to melting because there is more material in it's cross section for any given size (diameter). Draw a circle, then make a square or star inside the circle, see how much more material there is? Remember, it is the very tip of the line that does all of the work. The various square and star shaped lines are just gimmicks, good for advertising but useless for any improvement in trimming performance.