One of the critical points of the Nylon line is the part inserted in the hole of the shaft, which can have more or less sharp edges and so cut the line.
Some shafts have a smoothed hole, so the problem is reduced, but not eliminated. To strengthen such segment of the line some cover it by inserting it in a threaded tube, which can be bought at the electrician shop. The Nylon is inserted in the tube and the cover is made. Interesting idea!