The originals appear to be 8-32 machine screws. I'm hoping the deeper section will buy me a couple more threads in the outer frame. Based on the construction of some other port glass retainers, I've heard suggestions the threads should be through the outer frame (it saves time, it will hold better). however, I'm still going to try the blind seat per the original, worst case, I'll move up to 10-32 or 10-24 machine screws. :)Originally Posted by ebb
[edited 5 dec - I spent sunday drilling and tapping the frames.. the final implementation was 10-24 thread. I still get 8 turns or so per fastener]
Attached is a cross section: