Re-centering the suspension and slightly moving the counterweights to improve the balancing of the floating bench, we were able to close the three angular loops around 0 as working points.
Since it was not possible to set the right height of the bench, we opened the "cupola" to inspect the suspension while moving it with the stepper motors. The F1 stepper motor was stuck at the bottom end stop. After unblocking it, it was possible to move the motor and to center it. The F0 stepper motor moved a bit and then it remains stuck at mid range and it was impossible to move it up or down either sending command or by hand, ie the long screw was stuck in the peek part. We decided to dismantle it and to ship it back to Nikhef to repair it. Alessandro dismantled everything and found some bronze residual dust (coming from the screw) in the peek part, explaining the source of the problem. The peek part has been re-machined, the bronze screw replaced and the motor is under test. It will be shipped back to the site in the next day.
Meanwhile, to allow some measurement on the beam coming from EQB1 and back-reflected by the proper mirror on SQB1, this morning we blocked the bench not too far from its working position. It was possible for TX,TY, TZ, X and Z, while it was not possible for Y: the bench is almost 2 mm too high (note that the Y position is defined by mechanical structure and the screws used to block the bench). Using the beam coming from EQB1 we can understand if the bench is too high or the zero set-point of the vertical LVDTs is slightly off and fix it.
To align the BAB on SQB1 we measure with a diaphragm the height of the beam on SQB1
After we was sure that the retroreflected beam from SQB1 was not clipped, we re-posisioned the two reference diaphragms on the EQB1 out path (aftern EQB1_M5, toward SQB1). The height of the two diaphragms is at the nominal one, 110 mm.
Then we checked the beam height on SQB1 (see attached pictures) by positioning an other diapragm. All the three diaphragms were quasi completly closed and we checked that the out spot was at maximum of the intensity. In this way the error on the measurament should be just the error on the caliber lectures. Neverthless, considering an error in the caliber positioning, we can consider a factor 6 times larger, so that we exitimated the beam height on SQB1 to be 109.60 +/-0.3 mm (see attached picutures). We measure it in two positions and the two measurements were consistent.
In the condition reported in the previous comment, we were not able to avoid BAB clipping: traveling through SQB1 to the FISmir to be retroreflected toward EQB1 (1- inch retrorefletor for FIS measurament the beam results to low w.r.t. center of the optics, this it note expecialy on the diaphragms and into the FI. To have the BAB retroreflected without clipping, it must be raised from EQB1 to SQB1, so that in the right path from EQB1_M5 to SQB1_M1 it results tilted toward the top to center the SQB1 optics. See attached pictures
From what observed and reported in https://logbook.virgo-gw.eu/virgo/?r=51458, we deduce that the position of SQB1, at the present blocked in air, can be kept as reference to suspend it
