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VIS (SRM)
fabian.arellano - 15:35 Thursday 12 November 2020 (15447) Print this report
SRM F1 fishinfg rod.

This morning the fishing rod (FR) of the Standard Filter jammed.

In order to measure transfer functions I needed to move the keystone to nominal position, which is currently at -100 um.  I moved the keystone successfully from around 800 um to about -40 um, where it jammed.

Currently the temperature is 22.3 degress Celsius. When the temperature increases to around 23 degrees or more, the keystone will sag even more. Additionally, in vacuum the keystone will sag by 416 um.

Comments to this report:
fabian.arellano - 11:14 Friday 13 November 2020 (15461) Print this report

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.

fabian.arellano - 18:12 Tuesday 17 November 2020 (15479) Print this report

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.

fabian.arellano - 16:59 Thursday 10 June 2021 (17060) Print this report

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.
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