turner3d
Active Member
I recently went on a journey to model a reasonably accurate 3d-printable Star Trek TOS communicator. There are months worth of updates and discussion in another thread, but I've had so many inquiries about how I made the motorized moire that I think it deserves its own post.
While considering everything from stopwatches to stepper motors to drive the moiré, I discovered that battery-powered silent clock movements were a thing - they don't tick because of a smooth-sweeping second hand. Even better, they cost a whopping $7.59 for a 2-pack. They're way too big to fit inside of a communicator out of the box, but at that price, it was worth a shot to see if it was possible to hack one up to make it fit. Spoiler alert: it's possible (just barely). I'll try to cover everything you need to make your own 1.5V moiré.
Before diving in, you need to know that this isn't 100% screen accurate. Compared to the original hero props, the platter moves at 1/2 speed and its motion is smooth as opposed to jerking 6 times per second. On the other hand, it still looks pretty great and can be built for almost nothing.
You can remove the gear marked with a red X - you won't need it. You also don't need any of the gears on the underside of the chassis.
Grab the chassis by its edges and gently pull it out of the case. You should now have something that looks like this, minus the Photoshopped MS13-knuckle-style numbers.
You'll want to get familiar with the remaining 4 gears and their orientation. Gear 1 has a magnet on the underside and sits in a little cylindrical hole with a touch of light oil. Try to avoid removing this gear if you can. It stays put pretty well, and you definitely don't want to get any dust or debris under it.
Take your tweezers and remove gears 2 and 3 in that order, laying them on a clean, dust-free surface. Note that both of these have tiny secondary pinion gears facing down.
Remove gear 4 and with your wire cutters, trim the long second-hand shaft so that it measures 11mm from its tip to the large surface of the gear.
On the underside of the chassis, trim the long piece that gear 4's shaft comes through so that there is about 4mm of the small diameter piece remaining. When the gear is re-inserted into this hole, about 4mm of it should be protruding. Also trim off the other 2 chassis pieces indicated, and solder wires to the power connectors. Make sure you only feed this 1.5V. I tried feeding one 3.7V for a couple of seconds and it didn't burn it out, but it didn't run, either.
Next, you'll want to trim the clear-ish part of the shell. The knob/shaft normally used for setting the time can just be pulled out and tossed. The areas marked green in this picture are necessary for keeping the remaining parts in place, and the red line indicates where to cut. Keep in mind that this piece is quite brittle. A fast rotary tool with a cutoff disc works nicely to sort of melt your way through it. After you get the shell trimmed and the edges cleaned up, modifications to the clock movement are complete.
Now we get into the 3d printing. I used Nika3D Silver Silk filament to print mine, and the results are a pretty convincing aluminum finish. I also printed mine at a .08mm layer height with the last layer pattern set to "concentric" in the slicer. If you have a really smooth build plate, you can print the bezel face down with no supports, but if you have a textured plate, I'd print it face up with supports.
You may have to experiment with X-Y hole compensation in your slicer if the holes in the platter and chassis are too small to fit snugly on the clock parts. Make sure to do a test fit of the platter onto the second-hand shaft and of the moiré chassis holes onto the clock chassis pins.
Print pattern-bottom.pdf onto glossy photo paper for best results. Trim this with a pair of scissors to the edges of the image. The cutting job doesn't have to perfect at this point. Stick this centered to the flat side of the Moiré Platter (the smaller disc with the hole in the middle). Place this face down and trim off the edges of the photo paper with a hobby knife. It's very important that the paper is as even with the edges of the 3d-printed piece as possible and that they don't protrude at all.
You'll need to take your .75 mm thick clear plastic and cut it to size. I'll refer to this round clear piece as a lens from here on out. Take a small piece of double-stick tape and attach the 3d-printed "Moiré Lens Dummy" (the flat disc) to the clear plastic, then trim the clear plastic down to be the same size as the dummy. The side of a cylindrical carving bit in a Dremel works very nicely for this. Make sure that it's as close as possible to the size of the dummy. If the lens is even a little too big, it won't fit into the bezel. Once you're happy with the size, carefully pry off the dummy piece.
You need to get the lens as clean as is physically possible, being very careful not to scratch it. If there's any tape glue stuck to it, a little WD-40 does a great job of dissolving it. To finish, I washed mine very thoroughly with Dawn dish soap and dried it with a clean microfiber cloth, leaving it wrapped in that cloth until ready for pattern application.
Print pattern-top.pdf on your clear adhesive sheet, and attach it to your sparkling clean lens, making sure to get it lined up with the dot as close to center as possible. Try to push out any air bubbles you can, being careful not to rub off the pattern. If you used waterslide decal paper like I did, you'll now want to let it dry for a couple of hours. Once dry, lay it pattern-side-down on a clean smooth surface and carefully trim off the excess with a sharp hobby knife. On mine, this caused the decal to pull up a little bit in a couple of spots around the edge. If this happens, a paint brush with a tiny bit of water or even micro-set to re-wet around the edges will allow the pattern to re-adhere.
It's assembly time! First, assemble what's left of the clock movement. You're probably pretty familiar with this procedure by now. Next, press the platter onto the second-hand shaft. Slide the moiré chassis over the platter sideways, position the bracket holes over the pins on the clock chassis, and carefully press it into place. If you use too much force, you can snap off one of the feet and have to re-print the chassis. Press the lens into the bezel with the pattern transparency on the inside - this will not only make the lens surface shinier but will also protect the pattern from being scratched.
Placing the bezel/lens assembly onto the moiré chassis is the last step. It should friction fit fairly well, but it can be glued on if desired - just don't use any glue until you have the hole cut in your communicator shell and the chassis mounted through it. The model was designed to be mounted in a shell that is 1.5mm thick. If you used .75mm plastic for the lens and have a 1.5mm thick shell, there will be about .6mm clearance between the bezel and the face of the shell, just like in the original Alpha prop.
Enjoy!
While considering everything from stopwatches to stepper motors to drive the moiré, I discovered that battery-powered silent clock movements were a thing - they don't tick because of a smooth-sweeping second hand. Even better, they cost a whopping $7.59 for a 2-pack. They're way too big to fit inside of a communicator out of the box, but at that price, it was worth a shot to see if it was possible to hack one up to make it fit. Spoiler alert: it's possible (just barely). I'll try to cover everything you need to make your own 1.5V moiré.
Before diving in, you need to know that this isn't 100% screen accurate. Compared to the original hero props, the platter moves at 1/2 speed and its motion is smooth as opposed to jerking 6 times per second. On the other hand, it still looks pretty great and can be built for almost nothing.
Equipment needed:
- 3d printer - if you don't have one, you'll need a friend who does or a 3d-printing service. Note that these instructions are for FDM, but SLA should also be fine - just ignore the parts about filament
- Laser or inkjet printer
- Rotary tool (e.g. Dremel)
- Soldering iron
- Pair of sturdy wire cutters
- Hobby knife
- Tweezers
Materials needed:
- Digital Assets Download - https://www.turner3d.net/ClockMovementMoire.zip - Includes 3mf, stl, step files, and hi-res moiré pattern PDFs
- Alternate link for digital assets: Dropbox
- Silent Clock Movement - Amazon.com
- Silver Silk PLA filament - Amazon.com
- Clear adhesive printable sheets - my preference is printable waterslide decal sheets
- laser: Amazon.com
- inkjet: Amazon.com
- Photo printer paper of your choice
- Double-stick tape
- Rigid clear plastic sheet, 0.75mm (0.03") thick - I used a piece from an old poster frame, but the stuff is pretty cheap to buy
- Wire
- 1.5V power source
Let’s Do This
The first step: take the clock movement apart. There are no screws to mess with; it releases with a little prying on 3 latches. Pry them one at a time, pulling the case open at each just far enough to keep it unlatched. Once they're all unseated, turn the whole thing threaded shaft down, and carefully remove the rear shell.You can remove the gear marked with a red X - you won't need it. You also don't need any of the gears on the underside of the chassis.
Grab the chassis by its edges and gently pull it out of the case. You should now have something that looks like this, minus the Photoshopped MS13-knuckle-style numbers.
You'll want to get familiar with the remaining 4 gears and their orientation. Gear 1 has a magnet on the underside and sits in a little cylindrical hole with a touch of light oil. Try to avoid removing this gear if you can. It stays put pretty well, and you definitely don't want to get any dust or debris under it.
Take your tweezers and remove gears 2 and 3 in that order, laying them on a clean, dust-free surface. Note that both of these have tiny secondary pinion gears facing down.
Remove gear 4 and with your wire cutters, trim the long second-hand shaft so that it measures 11mm from its tip to the large surface of the gear.
On the underside of the chassis, trim the long piece that gear 4's shaft comes through so that there is about 4mm of the small diameter piece remaining. When the gear is re-inserted into this hole, about 4mm of it should be protruding. Also trim off the other 2 chassis pieces indicated, and solder wires to the power connectors. Make sure you only feed this 1.5V. I tried feeding one 3.7V for a couple of seconds and it didn't burn it out, but it didn't run, either.
Next, you'll want to trim the clear-ish part of the shell. The knob/shaft normally used for setting the time can just be pulled out and tossed. The areas marked green in this picture are necessary for keeping the remaining parts in place, and the red line indicates where to cut. Keep in mind that this piece is quite brittle. A fast rotary tool with a cutoff disc works nicely to sort of melt your way through it. After you get the shell trimmed and the edges cleaned up, modifications to the clock movement are complete.
Now we get into the 3d printing. I used Nika3D Silver Silk filament to print mine, and the results are a pretty convincing aluminum finish. I also printed mine at a .08mm layer height with the last layer pattern set to "concentric" in the slicer. If you have a really smooth build plate, you can print the bezel face down with no supports, but if you have a textured plate, I'd print it face up with supports.
You may have to experiment with X-Y hole compensation in your slicer if the holes in the platter and chassis are too small to fit snugly on the clock parts. Make sure to do a test fit of the platter onto the second-hand shaft and of the moiré chassis holes onto the clock chassis pins.
You'll need to take your .75 mm thick clear plastic and cut it to size. I'll refer to this round clear piece as a lens from here on out. Take a small piece of double-stick tape and attach the 3d-printed "Moiré Lens Dummy" (the flat disc) to the clear plastic, then trim the clear plastic down to be the same size as the dummy. The side of a cylindrical carving bit in a Dremel works very nicely for this. Make sure that it's as close as possible to the size of the dummy. If the lens is even a little too big, it won't fit into the bezel. Once you're happy with the size, carefully pry off the dummy piece.
You need to get the lens as clean as is physically possible, being very careful not to scratch it. If there's any tape glue stuck to it, a little WD-40 does a great job of dissolving it. To finish, I washed mine very thoroughly with Dawn dish soap and dried it with a clean microfiber cloth, leaving it wrapped in that cloth until ready for pattern application.
It's assembly time! First, assemble what's left of the clock movement. You're probably pretty familiar with this procedure by now. Next, press the platter onto the second-hand shaft. Slide the moiré chassis over the platter sideways, position the bracket holes over the pins on the clock chassis, and carefully press it into place. If you use too much force, you can snap off one of the feet and have to re-print the chassis. Press the lens into the bezel with the pattern transparency on the inside - this will not only make the lens surface shinier but will also protect the pattern from being scratched.
Placing the bezel/lens assembly onto the moiré chassis is the last step. It should friction fit fairly well, but it can be glued on if desired - just don't use any glue until you have the hole cut in your communicator shell and the chassis mounted through it. The model was designed to be mounted in a shell that is 1.5mm thick. If you used .75mm plastic for the lens and have a 1.5mm thick shell, there will be about .6mm clearance between the bezel and the face of the shell, just like in the original Alpha prop.
Enjoy!
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