Einstar 3D Scanner from Shining 3D - Cable Protector

I love my portable Einstar handheld 3D Scanner from Shining 3D, but worry someday the round connector could be damaged rendering the scanner unusable. Replacement cables are not available locally, and if one is needed expect to wait a few weeks for delivery. A protective cable cover is needed.

I searched for Protective Cable models online, but unfortunately was not able to find one, so I designed this myself.

This protective cable cap uses a Buttress Thread design that is based on a fitment tolerance of ±0.25mm gap between mating threads. This is generally enough clearance for most 3D printers with 0.4mm nozzles and 0.2mm layers to print this as a functional threaded assembly.

I printed mine on a Prusa i3 MK3s without any problems, and it worked right the first time.

I exported an STL file of the build plate ("All Parts Build Plate.stl") showing the orientation I used to print the parts. I used OrcaSlicer and printed them in Elegoo PLA Plus with 0.4mm nozzle and 0.2mm layer height.

Because the male threads capture the flexible strain relief of the Einstar Cable (ie. they are "die-locked"), I designed the male threads in 2 pieces, splitting them in half. The 2 halves are assembled with 2 small pins with a generous clearance for assembly. One half is standing up because I added an alignment feature towards the front of the piece, and the other half is laying down.

After printing, remove material, and assemble the 2 male threaded halves around the strain relief end of the Einstar Cable. Insert the 2 alignment pins. Apply a small amount of Cyanoacrylate (super glue) to the other half (don't allow the glue to the cable directly, just the mating 3D printed part) and assemble with the other half. Hold the two 3D printed halves together firmly for a minute, and allow glue to dry before screwing on the protective cap, to avoid gluing the cap on (ie. the cap should be removable).

There are a few cable loops in the design if you want to add a piece of string to keep the Cap tethered to the cable. I decided to wrap a small Zip-Tie through them instead, and use that to secure the 2 halves firmly together on the cable. If you ever lose the female threaded cap, you could print another one.

How I designed this part
I drew a profile of the Buttress Thread on a sketch, and then created a helix with 10 revolutions. I performed a sweep to create the threads. After splitting the male threads into 2 halves, I made a plane 1.5mm away from the split, and opened a sketch with an intersection curve through the threads. I then performed an extruded cut at ±3° to "Trim" down the last 1.5mm of threads close to the split line. This reduced the amount of post processing to have the 2 mating threaded parts match up with working threads. I then used a surface offset command with a distance of 0.25mm to create a cutting surface for the female threads, and used the Split Body command to form them into the mating half.