DuPont Polarizing Pin Plug

thingiverse

These small components fit snugly into Dupont-style pin header housings to prevent plugging in unless a pin has been left out in that spot. This allows for sufficient polarization protection while using standard 0.1" (2.54mm) pin headers, which are normally easily plugged in backwards. This approach worked well for a three-conductor cable; I simply used a four-position housing and filled one of the interior holes. The first picture shows how this prevents backing connections. For a six-pin cable, I didn't want to add just one position because seven-position housings are rare. So I added two positions and created a double plug for convenience. This is shown in the second picture. I had been using JST's MHT connectors on the board because they were polarized. But scaling this up proved problematic because the US$40 crimping pliers I found for them require separate crimp steps for wire and insulation, while the US$20 iWiss crimper does both wire and insulation on the DuPont-style pins at the same time. I really don't enjoy crimping; we couldn't find anyone to make our unusual cables for us (all that hot-melt is to reinforce the 30ga silicone wires from a slip ring... quite finicky to work with). Near as I can figure out online, these are called DuPont-style connectors because Dupont chemical company developed them as an application of one of their flame-retardant plastics. The manufacture of them is no longer done by the Dupont company. So, (R)/TM as appropriate on the name Dupont.