Originally posted by mrNewt For future adapters... you might want to consider using some type of lock-tight solution.
Given the size of the screw and where it mounts, I can't see lock-tite being that efficient at preventing the same sort of thing happening again. The threads in the adapter body were stripped out, and this was just from using the thing.
Just to say that the whole design is slightly flawed in the fact that the screw that holds the spring in place is so very small and fine that it will eventually strip out just due to the force of the spring being compressed and released as the adapter is mounted. Actually two screws on the spring would have been a more viable solution, spreading the force on the spring across two mounting points instead of just one.
I have a feeling it was a cobbled together solution on Pentaxes part to begin with- they needed to do something in the late 70's to address the need of all the owners of Pentax m42 glass that were probably a bit miffed at the shift to a bayonet mount. It's not like there was an obvious solution in the design of the bayonet mount to lock an adapter in place. They realllly should have considered modifying the registration distance of the K mount so that an adapter for m42 would extend slightly from the K mount.
Basically the adapter I had repaired failed due to it's age and the design flaw. I wanted to get it back in working order in such a way that I knew the inherent problem was dealt with. I worked on an electronics repair bench for 7 years, and that was always the rub when repairing mechanical systems- fixing for the long term, not just to "get it working" again.