Originally Posted by 52larry52

On nylon 1/4-20 wing hold down bolts, I taper the first 3 or 4 threads using a cheap kids pencil sharpener. The hand held pencil sharpener has a small razor blade inside it (don't tell the school board people or they will ban them) and cuts a nice clean taper on the end of the nylon bolts, making them easy to start. On metal wing bolts, I also taper the starter threads on a bench grinder, and of course that requires cleaning the threads after grinding the ends. This makes airplane assembly at the field less of a hassle.