[ccp4bb] Calibration question

[Jacqueline Day]

All-
   We are reevaluating the frequency of our pipette calibrations and were
tasked with determining the "norm".  How often do you calibrate your
pipettes?  Do you have different schedules for different purposes (i.e.
crystallization pipettes get calibrated every 18 months, while purification
pipettes are calibrated every 2 years)?  Who do you use for the
calubration?  Thanks, everyone!
    Jackie