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Trimmer mower line alternative

Swisher trimmer mower rope line

Today I tried putting a piece of nylon rope where the trimmer line usually goes.

It worked pretty good till it got frayed, and it still kept cutting, but not as fierce.

Maybe soaking the rope in some sort of adhesive would extend the amount of cutting each piece can do before it needs replacing?

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Great idea! Better "industrial grade." Maybe try knotting the end to prevent fraying?
Comment by doc Mon Sep 29 18:01:33 2014

Try melting the free end of the nylon string together before you put it in the trimmer. That should stop it from coming apart.

Adhesives probably won't work well because nylon doesn't adhere well. In composites manufacturing nylon films are often used as vacuum or autoclave bagging films because they don't stick to most kinds of resins.

To make adhesives stick to nylon, the nylon has to be given a flame or corona treatment. And the effects of those treatments generally don't last long.

Comment by Roland_Smith Mon Sep 29 18:30:39 2014
I think Roland is on the right track with melting the end. I'd also consider adding a hog ring to the very end (a heavy wire ring that that you pinch around the end as a clamp, kind of like what you see closing the end of mesh net bags of produce, or frozen poultry), then doing the melting. Then, even if the trimming broke down the melted nylon end, the wire would hold it in place. You could also weave a piece of baling wire through the last inch or so, then wrap it around the rope several times and melt the end. Have you considered trying a piece of braided metal wire? Or adding a wire rope clip to the end of the nylon rope (might be too heavy and would create undue engine wear)?
Comment by Rich Arnold Mon Sep 29 20:38:00 2014

While crimp rings are often used on steel cable, I haven't seen them used on cables made from nylon or other plastics. There are at least two reasons I can think of. First, thermoplastics have the tendency to flow under a constant load. This is called creep. I would guess that a crimp ring around a nylon cable would come loose in time. Second, a metal crimp ring would create a local increase in stiffness in the cable. Such combinations of stiff and flexible materials are often failure points.

Steel cable might be a bit too heavy. And I wonder if steel would be flexible enough. I would guess that strands might break on impact. Do a small test on a piece of plastic like the safety cover. Anything that can chew up the safety cover shouldn't be used. :-)

Comment by Roland_Smith Tue Sep 30 17:58:48 2014
I'll defer to Roland as to the advisability of a clip. I can explain the non-delegation doctrine and Lord Mansfield's Rule, but my education in engineering is limited to practical experience and what I can convince someone to teach me. I learned a few new things - thanks! Query: if the addition of a ring at the cutting end creates a stiff point subject to failure, how would the likely failure manifest? A break or unraveling? At the point itself (under the ring) or at the transition from flexible to stiff (before the ring)? You've got me curious.
Comment by Rich Arnold Tue Sep 30 21:52:04 2014

It could well be that the ring might fly off the line when using the mower. Due to creep the line material will deform and the friction between the ring and the line will lessen over time.

But as to failure mode, I would expect the outer strands to break at the interface between the ring and the line. In cases like these (dissimilar materials) much depends on the characteristics of the materials in question and the details of the interface; like if the edge of the ring where it meets the line is sharp or rounded. If the edge of the ring is sharp, it is like you're cutting into the line with a knife.

Finding the points with the highest stresses in a structure given its intended loads is an imported part of engineering calcuations and analysis. Given that failures to do this properly can be costly and even lethal, there are experience-based standards for e.g. constructing houses.

In general engineering we set the nominal load that a part is designed for, and then multiply that with a safety factor of three. The part is then designed so that the maximum occurring stress in in case of the triple load does not exceed whatever is allowable for the material and environment conditions. For heavy duty equipment like cranes, offshore platforms et cetera a safety factor of ten is often used.

Comment by Roland_Smith Wed Oct 1 13:46:21 2014
Thanks, Roland. I'm thinking melting is probably the most viable (and simplest) alternative, although one could try back braiding the end of the rope (similar to plaiting the end of a whip). Numerous examples and instructions can be found by searching for 'how to back braid end of rope.' Unless one back braided the entire length of the rope to be used, I think (at least from what you've explained) there'd still be a bit of a stiffness problem due to the transition to the increased rope diameter, and creep. This might be mitigated to an extent due to the same material being used. Interesting exchange. I appreciate you sharing your thoughts.
Comment by Rich Arnold Wed Oct 1 20:31:15 2014

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