This post was from David Carter
Pin Tool Position error in 384 well plates and solution
We had a problem with pins scraping on the edge of 384 wells, leaving droplets of liquid on the edge and depositing less than needed.
Discovery: Slowed the robot down to 10% (Instrument/ Hardware Setup/ Pod 1/ Additional settings/ Speed limit 10%)
Tripped the light curtain with the tips down. Shining a flashlight on the wells showed the pins were front and slightly left of center; pressed against the well edge. Several pins did not fully fall into wells during slower descent.
Possible Cause: labware definition was incorrect
Discovery: Manually moved head to determine good central position (Instrument/ Manual Control/ Advanced/ Pod 1/ Moved Right 0.02 then another 0.03. Moved back -0.05 then another -0.05 by typing numbers directly into fields rather than using arrow keys. Remember minus sign)
Solution: Edit labware definition (Project/Labware Type/ double click on in this case AB Gene 1055 384/Wells_1/Well offset changed from x=1.245 to 1.295 y=0.845 to 0.755)
After fix, tips hit center and day's work completed.
Outstanding problem: On 8/24/07 when writing up this post, x and y numbers had defaulted back to 1.245 and 0.845. Don't know how to make changes stick.
Outstanding problem: I think the labware definition offsets refer to distance from top left corner of plate, but we had wedged the plate bottom-right to eliminate the little bit of slop in placement. Should we always push the plates back and left instead?
Possible alternative: Framing error. I did not try re-framing the deck, which is running fine in all other applications.
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