Hamilton Nimbus384 tip eject z-offset problems

Hey guys,

First post here - I see lots of great resources and I’m happy to be a part of the community. Hoping someone can help with some issues I’m having with a Hamilton Nimbus 384.

I have noticed that when ejecting tips back into a tip rack, the head pushes down on the tip rack. This causes the bracket that mounts the head to the gantry to flex. We move tips around in racks frequently and I’m concerned that this repeated flexing will cause the head to loosen and fall out of alignment. The head was starting to pitch forward just before our first PM and it was realigned and calibrated then, but I don’t know how long that will last.

Some details on the problem:

  • The Z-position of the head during tip pickup looks correct. This only happens on tip eject.
  • This only happens when ejecting tips from a Method. When I pickup and eject tips from User Control / Teaching the Z position looks perfect on both pickup and ejection.
  • When ejecting tips in a Method, the Z position of the head is about 2.5 mm lower than when ejecting tips in User Control / Teaching (pictures attached).
  • I can adjust the teach point of the tip rack so it will eject tips nicely, but then on tip pickup the head doesn’t go down far enough to pick up the tips correctly (the tips are not fully seated on the probes).
  • This behavior is consistent at all positions of the deck.
  • I am using the default deck layout and labware definitions that were provided when the instrument was first installed/verified by Hamilton.
  • The instrument was purchased new about a year ago and it just had the head calibrated during a PM.

I’m still learning exactly what I can expect from this instrument. Is this behavior expected? Is there anything I can do to change it? It looks like there is some additional offset of about 2.5 mm being applied to the Z-position of the head when the instrument ejects tips from a method.

Thanks in advance for any help or ideas.

1 Like

Hi Erik,

Welcome to the forum! Can you please confirm you’re using the conductive 384 tip labware definition (may also be labeled NTR)?

Aside from that, it may be best to involve your local support team. Please let me know if you’re interested in pursuing this option and I can help get you in touch with them!

Thank you,


Hi other Eric

Thanks for the reply! So I take it this is not expected behavior?

The labware definition is 384head_384tips_50ul.rck - so it doesn’t specify clear or conductive tips. I’ve tested it with both types of types and the behavior is the same regardless.

I’ll reach out to our FSE and see if they can help with this. Thanks!

Hi Erik,

I don’t have ready access to a NIMBUS 384 VM but for the STAR/VANTAGE product line, the 384head_384tips_50ul.rck definition is for Axygen tips. For the Hamilton 384 50μL tips in NTRs the definition is: TIP384_384TIPS_NTR_50ul.

I would defer to the local team to investigate further - I have let them know of your issues and they should be following up.

Thank you,