Today I got the cables laced with a new, more robust-seeming cable than the cotton yarn I’d been using.   I also plumbed up  the fluid delivery needle valve and solenoid,  so it’s ready to go.

I let the system cycle open and closed a few thousand times while I worked,  once every second or two.

A hiccup occurred when the stepper motor was accidentally overdriven due to a mis-setting of the “run current” on the Vexta stepper driver.  This overheated the motor and caused a motor fault,  most likely a shorted coil.  Thankfully I’ve got a bin of stepper motors from various past projects and all that’s required to fix it is to 3D print a new adapter cog,  which links the new motors 0.233″ diameter shaft,  to the existing bicycle sprocket gear.  The old adapter was a 0.25″ diameter shaft.  Thankfully, modifying the CAD file, exporting a new STL model,  and 3-D printing a new pulley adapter requires only about 15 minutes of my time (with the print then occurring in the background for maybe 30 minutes).    Wiring in the new motor (identifying the color code of the stepper’s wires and soldering it to the cable connector) will take perhaps 45 minutes.