ORIGINAL: Instructor
That is a GOOD idea, but the threads that are on the rod, 6X32, I think, are not intended for load. What you need is a Williams thread. They are threads that have a flat edge and a rather thick tooth. If you look at screw jack stands, then you will see what I mean. The 6X32 threads will wear out much faster than the Williams thread. Maybe I'm wrong, but thought I would mention it......
Larry
Thanks for the input Larry.... actually the rod I am using is a stainless steel 4-40 threaded rod. So far, the gear I modified all used a trunion control "T" that is tapped for a 4-40 thread.... lucky me I guess. I'm curious if other air retract manufacturers use 4-40 or something else. I know exactly what you mean about how the threads are cut for jackscrews... interesting fact I might have to consider. I was in fact concerned over thread wear and hopefully this weekend, I'll run a test where I (actually a PIC) will constantly cycle the gear (every 15-20 seconds or so... still not realistic use but good enough for a test... I just do not want to overheat the motor.... as this probably will not happen during normal use), just to see when the unit fails... and mainly to see WHAT fails frist! I also plan to test with a brass 4-40 threaded rod as someone told me that brass-on-steel wears less than steel-on-steel..... no? I'm an electrical engineer, not a mechanical engineer (although I attempt to think like one once in a while.... LOL)
Thanks again for your thoughts....