Prototype 1

March 18th



Using a 1Nm stepper motor, at 600-700 RPM we can fully depress the ‘plunger’ in 0.5s by winding up a timing belt.
Springs (in green) enable return rise.

Frame in 10mm lasercut acrylic.

Link to short video:


  • The stepper also provides a very rapid response,
    allowing to correct the pressure in the system at +50 Hz.
  • A NEMA23 stepper motor does not provide enough power to reliably run the machine at its outer envelope. (600mL at RR=35 with I/E=1/3 and Ppeak=40cmH20)
  • It is easy to fool yourself you just might get there with a bit more tuning. You should not try. Choose a motor with a solid safety factor on required power.