Weird Dimension shift of specific labware

Hamilton (Venus)
1

Hey guys,

I’m experiencing a really odd situation. I created a specific method with a fixed deck layout for MIC protocol. For some reason, using the very same method, with no layout modifications, it pipetted outside the plate wells. I paused the protocol, used “Teach”, ajusted the new location. All the plates had a 5mm shift in y axis. So I implemented the 5mm shift to all plates in the same carrier and the protocol worked fine.
Until yesterday, when I ran the very same protocol, with the layout and the behaviour persisted. When I used “teach” again and adjusted location, the y axis was shifted again, but now 6.5mm at the oposite direction. Things to take in mind:

  1. No error appears at runtime, it pipettes normally, but in the wrong coordinates;
  2. No layout or method changes were implemented in between runs that justify the dimension shift;
  3. The equipment (Microlab Star) was not moved recently;
  4. The very same plates were used in both runs;
  5. The carrier was placed correctly and so the plates, I double checked;
  6. The room the equipment stays is always at 20°C - 18°C;

Can you help me with this? What may be causing this?

2

I would check during instrument power up and initialization to see if it’s consistently homing in the correct location and there’s no debris that prevents it from doing so.
It’s also possible that the x axis belt for the gantry is slipping due to improper tension, or age.

1 Like
3
  • Any shaking elements on deck? If this is a HHS carrier, make sure the thumb screw in the back is locking the carrier in place
  • Visually confirm there’s no screws or pipettes stuck in the back which could lead to a false stop when sliding racks/carriers in to the deck.
  • Is the deck level? Are the casters locked (if this is installed on a table)? Any damage to the metal springs on the nests? Maybe one broke off recently, but this seems less likely with the whole carrier being affected.

Besides this, has the problem persisted or was this a one time occurrence? If you get the same problem every time (e.g. 5mm shift) then this is something systemic and has a traceable source. If its inconsistent shifts at random intervals I’d look into instrument maintenance and possible step loss.