It’s been a long time coming, but I’m finally ready to call my Discovery communicator files “done.” The intention was to get this posted late last fall or early winter – but I kept finding things to adjust, fiddle with, and refine. I don’t even have one built from the latest version and was going to wait until then to post, but if I don’t put a hard stop on it, it’ll never get done!
This thread will document my Discovery communicator project from start to end (and hopefully beyond with builds by others). First I’ll present an overview of the prop and my files, along with a focus on some notable features and mechanisms. Then in later posts I’ll show my first prototype along with a build log of the more finalized design. I hope others will join in with their own builds from these files!
So! This is an original communicator prop from Discovery (as seen in the behind-the-scenes book Star Trek Discovery The Official Collector’s Edition):
This is a render of my design:
(I noticed some issues even when making the above image, but again, it has to be called close enough and done at some point )
A few more angles:
And the weird sunken-then-raised hinge coin knurling:
One thing that I never fully figured out on this prop was this knurled feature. The original communicators were machined from aluminum, meaning that there are only so many ways to achieve this particular detail. On the original, the knurled section is potentially a separate part inserted into a slot/groove in the “hinge wheels” - for example see the slight irregularity in the lower left two images below which could be an edge that wasn’t deburred properly, or damage that occurred while assembling the hinge. In addition, the small domed disc beneath the two stainless socket head cap screws appears crooked on the right hinge of the communicator that was on display in Las Vegas in 2017, indicating this could be a separate part as well. For simplicity my model keeps these and the lid as all one piece, with the two socket head cap screws affixing two inward facing hinge pins.
The 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).
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 housing for a 7th generation iPod Nano/miniature android phone (more on this later) – the only working feature in the metal itself is the lid spring mechanism. This acts to pull and hold the lid shut when rotated past a certain point, and to push 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 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:
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:
The function of the spring mechanism is visible on the show with how the actors must first pull open the antenna lid to a certain point with their second hand before being able to perform the classic flip open with the hand holding the communicator body. The lid also remains fully open at a consistent angle, independent of support from fingers as on the TOS communicator.
As previously discussed on this board, the season one Discovery communicators used both a tiny Android smartphone and a 7th generation iPod Nano. Why the switch from the former to the latter, we don’t yet know. I designed mine to work with both as well. The smartphone fits loosely in a raw printed shell:
Some shimming at the corners will be necessary for the screen to keep proper alignment, but the overall fit is close. The three pin holes for access to the power and volume buttons are present in the appropriate locations as well, as on this original (also visible in the BTS video):
For the iPod option, I designed a frame to hold the iPod in place. The BTS video shows a similar piece for that iPod, made of a white/grey material and what appears to be an integral lever on the top edge (possibly used to hit the sleep/wake button on the iPod by pressing upwards on the screen through the round bezel (“moire ring”), or by pressing upwards on the frame through a possible pin hole on the lower end of the comm - there are holes as part of the design there but it’s unclear if any are through-holes). The original frame:
In a somewhat clumsy attempt at allowing the iPod’s sleep/wake and play buttons to be accessible from the outside of the communicator without use of pin holes or any external features not present on the original, I’ve designed a small sliding arm that attaches through the rear shell to the delta on the back of the communicator. Pressing the delta sideways in turn presses the play button, and pressing the delta downwards presses the sleep/wake button. Also there is a nub to attach to the rear of the middle communicator button to allow it to hit the iPod’s home button (printed part tolerances are likely too rough to work right off the printer - will need some hand-tool adjustment of the shell).
With the iPod in place:
This whole mechanism is perhaps not the most elegant solution and 3D printing is not great for getting a close tolerance mechanism like this to work. Therefore I left the hole through the rear shell at its minimum size to help locate the delta in its proper position. If you print this and want to try this iPod button mechanism, the hole in the rear shell will need to be enlarged. Another possible mechanism would be for the delta to move the iPod frame itself, which would bump the iPod buttons against static stops on the interior of the body, with springy foam to press the frame back into proper alignment within the body.
A custom LCD screen/Arduino solution might be a better option for fan builds at this time given the current high prices of the 7th gen iPod Nano, and the abysmal standby battery life of the Posh smartphone. Then an opening chirp could more easily be incorporated as well.
6x 18-8 Stainless Steel Socket Head Screw 0-80 Thread Size, 3/8" Long 92196A057 https://www.mcmaster.com/#92196A057 (Hinge pins (L & R))
4x Black-Oxide Hex Drive Flat Head Screw 2-56 Thread Size, 3/16" Long 91253A075 https://www.mcmaster.com/#91253A075 (Affixes lower shell to body)
2x Steel Extension Spring A 0.5" Long, 0.018" Wire 9654K942 https://www.mcmaster.com/#9654K942 (stiffer than B)
2x Steel Extension Spring B 0.5" Long, 0.014" Wire 9654K941 https://www.mcmaster.com/#9654K941 (softer; better for a printed communicator)
(choose A or B)
1 brass or steel round rod 1/16" outer diameter, 2" long
Optional (for iPod mechanism):
2 Narrow Hex Nut 2-56 Thread Size 90730A003 https://www.mcmaster.com/#90730A003 (Inside face of “delta”)
2 Phillips Flat Head Screws 2-56 Thread Size, 1/8" Long 91771A074 https://www.mcmaster.com/#91771A074 (Through “button arm” into “delta” hex nuts)
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. This 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 (thanks Ryan!) 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”
Notes on Assembly:
- You’ll need a 0-80 tap for the hinge pin screws ($6 on Amazon) 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.
Now finally, the files. I am sharing these with the stipulation that by downloading the files you agree to use them only for personal builds - not for commercial purposes. The files are not to be shared, modified, sold, or posted anywhere else without permission. Prints, castings, and/or builds of these files are not to be sold in any form.
lower shell.stl (218.1 KB)
bezel.stl (125.6 KB)
faceplate brass.stl (88.8 KB)
faceplate charcoal.stl (95.4 KB)
faceplate.stl (182.5 KB)
hinge pin left.stl (272.2 KB)
hinge pin right.stl (272.2 KB)
delta.stl (345.7 KB)
ipod button arm.stl (61.3 KB)
ipod insert.stl (26.1 KB)
bar button.stl (517.2 KB)
button.stl (610.6 KB)
lid thicker.stl (1.6 MB)
ipod home button backer.stl (154.0 KB)
body shell.stl (1.2 MB)
lid.stl (1.6 MB)
That’s the last of it! Please feel free to use this thread to post your builds!