Re: OT Stepper motor for control pumping

rather than have an openloop solution (prone to problems with
bubbles etc) you might consider putting the jar to be filled on a
glorified see-saw, counterbalanced with the relevant amount of
weight. When the see-saw tips then a micro switch or reedswitch can
cut off the flow by turning off the motor. The pumping can still be
done with a syringe pump, just drive it with a heavily geared DC
motor. If you really want a stepper then just use a single axis
driver and a little pulse generator made with a 555 timer, this
could then be switched off with the limit switch. The flow rate
would be altered by changing the 555 frequency.

Remember that the see-saw does not have to move far, it can be
mechanically limited so you could even have the empty jars sliding
onto it automatically etc etc.

Graham