I just got off of the phone with Harmon Lange and he asked me to relate my experiences with attempting to do the leg gear modifications, so that others might not have to repeat my experiences.
I work at the University of Wisconsin-Madison in Mechanical Engineering. We have a fully equipped machine shop. Before sending the leg to Harmon for rethreading, I asked the machinists and tool makers in our shop about doing the threading. While they all indicated that it could be difficult, the consensus was that with a good die, it should not be a big problem.
So I bought the correct die from MSC for ~$54 . When it arrived, I took it and the gear leg to the shop. When I asked the best method for fixturing the leg prior to doing the threading, before I could protest, one of the guys working at the shop grabbed the leg, put it in a pipe vise, tightened the vise, and damaged the surface of the leg. I was pretty certain that this was a big problem, and would likely preclude the leg from being reused, however, we went ahead with the retheading anyway. More on this later.....
We then proceeded to do the threading. Initially, it went well, however, somewhere during the rethreading, it became impossible to continue to thread, or to get the thread to be of sufficient depth. Perhaps parts of the die itself were embedded in the leg, although this was not observable to the eye.
After three plus hours of cursing and sweating, we gave up. I was already concerned about the scoring on the leg, and so I packed the leg up, sent it to Van's for match drilling of a new leg.
Today during my discussion with Harmon (BTW, he is originally a Cheesehead), he told me that they are very careful with the surface finish of the leg and that it would not be a good idea to use a leg with a nicked-up surface finish.
Sincerely, this was, without question, the worst experience I have had with airplane building, and I would not attempt to do it again.
I work at the University of Wisconsin-Madison in Mechanical Engineering. We have a fully equipped machine shop. Before sending the leg to Harmon for rethreading, I asked the machinists and tool makers in our shop about doing the threading. While they all indicated that it could be difficult, the consensus was that with a good die, it should not be a big problem.
So I bought the correct die from MSC for ~$54 . When it arrived, I took it and the gear leg to the shop. When I asked the best method for fixturing the leg prior to doing the threading, before I could protest, one of the guys working at the shop grabbed the leg, put it in a pipe vise, tightened the vise, and damaged the surface of the leg. I was pretty certain that this was a big problem, and would likely preclude the leg from being reused, however, we went ahead with the retheading anyway. More on this later.....
We then proceeded to do the threading. Initially, it went well, however, somewhere during the rethreading, it became impossible to continue to thread, or to get the thread to be of sufficient depth. Perhaps parts of the die itself were embedded in the leg, although this was not observable to the eye.
After three plus hours of cursing and sweating, we gave up. I was already concerned about the scoring on the leg, and so I packed the leg up, sent it to Van's for match drilling of a new leg.
Today during my discussion with Harmon (BTW, he is originally a Cheesehead), he told me that they are very careful with the surface finish of the leg and that it would not be a good idea to use a leg with a nicked-up surface finish.
Sincerely, this was, without question, the worst experience I have had with airplane building, and I would not attempt to do it again.