Hi to all: Some on this list have wondered about double helix threads on agraffes. I liked the exercise of wrapping a thread around the shaft to see where it ends up after just one revolution. Now for a sex thriller, try this same trick on a tuning pin. You will find that there are six threads per revolution around a tuning pin. Sometimes they overlap and make the tuning pin a little rough. This can account for some of the variation we experience in final torque measurements. Getting back to double helix. You may remember that the Kimball co. used many double helix screws in their case work. This cut the time in half that it took to run a screw down. They were also harder to remove. Jim Coleman, Sr.
This PTG archive page provided courtesy of Moy Piano Service, LLC