Here I report the expected position of the F1 keystone in vacuum and at 23 °C.

• Displacement due to buoyancy in at 23 °C: 416 µm. See klog 15322.
• Displacement due to temperature chage from 22.3 °C to 23 °C: ( 870 - 349 ) µm = 521 µm.  
  • Position of keystone in air at 23 °C: 349 µm. See klog 15322.
  • Position of keystone in air at 22.3 °C: 870 µm (at  00:35:00 UTC on the 12th of November 2020 before moving with FR).
• Position after the FR jammed: -43 um (at  00:56:00 UTC on the 12th of November 2020 with temperature 22.3 °C).

The  expected position of the F1 keystone in vacuum and at 23 °C is then: ( - 43 - 416 - 521 ) µm = - 980 µm.

On Friday I tried moving the fishing rod when applying large amounts of actuation to the keystone. I used 25,000 counts both ways and the keystone moved roughly about 1 mm.

Unfortunately, this strategy did not help. The FR is still jammed.

With Ikeda-san and Hirata-san.

Today we excecuted Ikeda-san's rescue plan for jammed fishing rods on F1: it worked!

• Once the FR was free, we moved the keystone close to 416 µm, which is the size of the buoyancy affect.
• The polarity of the stepper motor is such that a negative number of steps moves the keystone up (entry 4721).
• We set the size of the step to FULL STEP, which is quiantified by the number 1.
• We set the velocity and acceleration to 500.
• We actuated with -1000 full steps and the FR began moving.
• Next we changed to micro-steps, which are 256 full steps and we moved it up all the way close to 416 um.
• We set the (physically) lower software limit switch to 3,280,000 steps.