Ribbon Wire Cutter (a.k.a.: Mr. Chompy)
Channel: Solarbotics
Date: 21/11/2012

We've got several kits that use cut wire and cut ribbon cable. We didn't need an expensive $1500 ribbon cutter/stripper, just something to snip lengths of multiconductor ribbon wire into 8" chunks. Time to grab the OpenBeam (https://solarbotics.com/catalog/prototyping/openbeam/) and...

    One Arduino Uno (https://solarbotics.com/product/50450/) with a CMDR Motor / stepper driver shield (https://solarbotics.com/product/39290/)
    Pneumatic control parts from a dismantled pick-and-place machine
    1 Stepper motor
    Ebay'd "PanaPress" 507 Flat Ribbon Cutter
    Ebay'd spring-return, 1.5" stroke pneumatic cylinder

So what's involved? First thing, if we're going to beat the hell out of a steel blade by ramming it through a ribbon cable, let's make it a bit easier on the blade. We machined a 1/4" groove into the base of the cutter, and inserted a 1/4" square stick of UHWM ("Ultra High Weight Molecular") plastic. It's about as tough and slick as teflon, but not as expensive.

After a half-hour of mocking up various geometries, we started drilling and tapping into the OpenBeam sections to build a sturdy base to take the beating of a pneumatic cylinder. We didn't even have to cut any OpenBeam, as our variety pack had lengths ideal for our purposes. The neat center hole in the channel profile accommodates #6-32 tapping nicely, which has held up quite nicely (even when other parts have shaken themselves entirely loose).

With the ribbon cutter mounted under the pneumatic cylinder, we connected the two, and mounted the cylinder between two beefy 6mm laser-cut acrylic mounts (yay for lasers!). Again, another Arduino and shield were used to drive the air-solenoids, and to drive the wire feed mechanism built from a stepper motor and more OpenBeam mounts.

After the beta-tests proved successful, acrylic safety shields and an emergency-stop button were added, and Mr. Chompy was put into service! On reset, Mr. Chompy cuts 25 sets of wire and dumps it into a bin that is (naturally) mounted underneath with more OpenBeam.

So it's a tinkerer's delight - Arduino, steppers, shields, OpenBeam and a pile of junk made for two very useful machines in short order!