During operation today, it was observed that the main vault door had issues opening.. typically when the door was around 80-90% opened, it would stop motion. Note that this issue has allegedly been present since early 2023. It appeared that the motor was still spinning but the clutch was slipping. This issue was consistent and observed multiple times when trays 2, 5, and 6 were engaged (note these are all on the same side of the vault). It was overcome by backing the door up slightly then trying again. The door close function worked with no issue.

It is suspected that there is a problem with the clutch or potentially a piece of debris on the track. [no longer true after 2023-11-17 inspection]

Edit [2023-11-17]: Maico Dalla Valle and Adam Newsome inspected the vault on 2023-11-17. It was very clear that the door, when opening, is rubbing up against the rails. Specifically, the side rollers located on each side of the vault (red housing). There are clear wear marks on each side. The skew is obvious because on one side, the wear marks begin immediately and stop halfway through travel, whereas the other side shows the reverse wear pattern. It is therefore suspected that the skew has become so significant that the friction is too high towards the end of travel which causes the clutch to slip. The travel rails were cleaned (significant grime buildup) and the offending side was filed down slightly (a sharp burr was present from the wear). It is not advised to adjust the clutch. Next steps: open and close the vault with no trays engaged to see if the issue persists (perhaps weight distribution was the issue), and then try different combinations of weight distribution to try to replicate the issue. After this, measure separation distance between guide rails at different points and try to identify the source of the skew issue and rectify it.
 

Edit [2023-11-20]: Maico and Adam performed further investigation by opening and closing the vault door under 3 different configurations: no trays engaged, 2 trays engaged on West side, 2 trays engaged on East side. The previously observed stopping issue was not observed this time under multiple cycles with each configuration. It is noted that the door appears to slow down slightly and experience a bit of a "chugging along" motion towards the end of travel when opening. Based on these observations, it is concluded that the cleaning and filing helped enough to allow the door to fully travel open/close without getting stuck. The root cause of the issue still remains to be fixed, but for now there is no major concern. Before end of 2023, measurements and planning will be performed to develop a proper repair for the root cause. It is expected that either late 2023 or early 2024, the repair will be attempted.

Edit [2023-11-22]: during a routine spent target exchange, the issue was not observed when opening tray number 2. 

Edit [2023-11-24]: a dial indicator was set up on the vault on the right side (looking down from above), mounted on the traveling part with the tip touching the black structural member where the wear is observed. The purpose is to determine how much out of alignment the door is with respect to the structural assembly. The following was observed: approximately halfway through the travel, the indicator read approximately 185 thou of travel. This corresponds to when the wear marks start to occur and where the small red enclosure around the roller wheel interferes with the structural member (causing the wear strip). At this point, as expected, the indicator no longer changes because the roller wheel has bumped up against the structural member. This implies the gap between the structural member and the roller wheel, when the door is closed, is approx. 185 thou on the right side (and 0 on the left side). These values reverse around the midpoint of travel. It is suspected that because of this, and because there is a small observable gap between the door and the vault when it is fully close, the right and left side of the door are not parallel with respect to each other. In other words, adjusting the angle so that the starting gap is roughly 92.5 thou on each side should resolve the issue. Measurements to confirm parallel-ness between each side will be performed, and then an adjustment will be made to create even gaps between each side at the starting point. After this, a dial indicator will be set up again to confirm that, when opening the door, the gap is maintained throughout the duration of travel. Small deviations are acceptable, but in general what should be observed is a roughly constant gap, and no interference (i.e. if the gap begins at 92.5 thou, it should not drop to 0 or not exceed 185 thou, but should hover somewhere on the order of 20 to 140 thou, for example).

 

Edit [2023-11-24, 2]: a dial indicator was set up on the left side of the vault in a similar manner as described above. In this case, the indicator's reading remained roughly constant during the start of travel (starting with the door closed and opening it up), with only up to around 10-20 thou variation at first slowly, followed by a slow increase to up to approximately 135 thou. This is similar to the 185 thou observed on the other side. One suggested means of resolving the issue is: raise the entire door slightly with overhead crane, translate it sideways approximately half of door's lateral travel distance (i.e. around 90 thou) and then lowering it back down. This should, in theory, be acceptable. It may not resolve the issue of whether the door is rotated, but should give enough clearance on both sides throughout the entire range of motion to be deemed an acceptable fix. Other opinions will be gathered on the subject to determine if this could work.