[Jeff, Daniel]

From one of the Holometer bend cubes (with only 3 lifting points), we took off the 8" diameter bellows and 10" to 8" Zero Length Reducer CF Flange (while still attached to each other) and wrapped the open end in UHV foil. The cube was fairly dirty on the inside and outside, so we lightly cleaned the outside. We did not clean the inside, but there are particulates that need to be removed.

We then added a 10" blank CF Flange. We felt a lot of resistance from one of the holes, so we used a 1.25" long screw instead of a 1.75" long screw to avoid the bad part of the thread in the cube. As I was tightening the flange to the cube (at around 20 Nm), I stripped the silver-coated screw. See the screw in the foreground of the attached photo. I was able to tighten the other screws (at around 45 Nm) so that the flange is flush along the cube face and the gasket isn't visible. It isn't noticiely worse where the screw is missing.

After I removed the stripped screw, I was not able to add another screw into the cube. However, I was able to "touch up" the thread with a 5/16-24 tapered tap (making sure to only apply a light amount of torque so that the existing thread is only improved) and insert a 1.75" screw. I felt the same resistance as I did with the initial screw insertion, so I want to use a 1.5" long screw. This will hopefully avoid the two bad parts of the thread in the cube that I believe exist: the shallow part, which might be my fault, and the deep part, which existed. We can get this screw from Duniway or McMaster.