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Entry  Fri Mar 2 19:33:14 2018, awade, Misc, Purchases, New Wiha 2.0-7.0 Nm torque control driver IMG_2318.JPGIMG_2319.JPG
    Reply  Sun Mar 4 05:22:05 2018, rana, Misc, Purchases, Torque spec for optical mounts 
Message ID: 2115     Entry time: Sun Mar 4 05:22:05 2018     In reply to: 2113
Author: rana 
Type: Misc 
Category: Purchases 
Subject: Torque spec for optical mounts 

The case I was describing is with the BA-1, BA-2, or BA-3 from thorlabs, using a steel (18-8) screw and a SS washer. In this case, you want to go to ~75% before plastic deformation of the aluminum. In this situation, the screw and the base will be elasticly deformed. More tightness will make it plastic and then slowly drift. Less will just give you less stiffness against vibration.

For the case of the 1/4-20 screw with washer in a fork clamp, I expect it can go more, but probably not necessary. To test for drift, we would need an ultra stable Mach-Zender and a long term visibility test, as was done for the stability tests of the Japanese Super Duralumin mounts that Koji has.

Dennis Coyne has a formula to figure out these numbers. I'm going to get to the bottom of this and make it part of this summer's course on Lab Skills.

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