I really love the design of the communicator prop from Star Trek: Discovery. It's a sleek, cool original design that incorporates cues from the TOS and TWOK communicators to ground it in the lore of the show. It just screams Trek as soon as you see it.
A behind-the-scenes props video from September 2017 gave us a fantastic look at the innards of a hero communicator. It’s really very elegant in its simplicity -- the communicator is essentially an elaborate CNC machined aluminum housing for a 7th generation iPod Nano. The only working feature in the metal itself is the lid spring mechanism.
This printable communicator is designed to be assembled in a way (and with a lid mechanism) that mimics the original as closely as possible given the current available reference. Not pictured in the renders are the eight socket head screws that hold the parts together as on the original. I omitted the threaded inserts that are visible on the original.
The BTS video is not clear enough to see what the actual attachment of the spring to the hinge pins is, but this is what I came up with. An extra stainless socket head cap screw acts as a pin for the spring to hook onto and rotate about. This acts to pull and hold the lid shut when rotated past a certain point, and to pull and hold the lid fully open going past that point in the other direction. Two springs loop over a fixed brass (steel?) bar that spans the comm body cavity; the other ends of the springs appear to be attached (off-axis) to the lid hinge pins. The springs are constantly under tension, with the points of least strain being the lid fully open and fully closed.
The image with the test print demonstrates the hinge function. From left to right: Fully closed lid, lid open to neutral point with maximum spring extension (where the lid is rotated such that the spring falls exactly across the axis of the hinge pins), and on the right, fully open lid. The hinge pin pieces also incorporate physical stops that prevent the lid from rotating past 130 degrees.
Notes on Printing:
The STL files are in millimeter units.
Some clearances are worked into the models, but for the lid in particular, because it is a moving part, I recommend scaling it up by 1-2% before printing. Same goes for the "bar_button" - scale it down 1-2%. These adjustments will not be visible to the eye and will provide some additional clearance for the thickness of paint and primer.
A second version of the lid (lid thicker.stl) is provided if the standard lid proves to be too challenging a print. This is primarily intended for those using resin printers - some test prints on a Form 2 revealed that the very thin nature of the lid could cause cracking during the curing process. Hopefully this version will be less prone to that, but the idea is untested.
Two versions of the faceplate are included. One has the brass and painted layers as one piece, and then there are individual files for each piece. On the original communicators that rear layer is made of actual sheet brass.
Print 3 copies of “button.stl”
- The file “buttons and bar grouped.stl” is a sprued assembly of three buttons and the bar button which will be more convenient and cost effective if you wish to have metal pieces made by Shapeways.
Notes on Assembly:
You’ll need a 0-80 tap for the hinge pin screws ($6 on Amazon https://www.amazon.com/gp/product/B000SKVEYI/ ) along with a corresponding tiny 3/64" drill bit.
A 2-56 tap for the main shell threads might be useful but at that size and depending on your print material, the screws may tap themselves
When assembling the lid springs, affix the brass rod through the spring loops first, then use a small metal pick or pliers to hook the other loops over the screws/posts on the lid hinge pins.
- It helps to smooth up the hinge holes in the body (taking care not to go too far) with a 23/64 bit. You can use a 1-2-3 block to help align the body at a right angle to the table of the drill press. Don’t forget a little clean up of the edge with a countersink bit.