Split Flap Assembly and Design
by TheRobotsAreComing in Workshop > Laser Cutting
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Split Flap Assembly and Design
![Screen Shot 2021-12-06 at 2.06.56 PM.png](/proxy/?url=https://content.instructables.com/FFI/WV6R/KWUOSF08/FFIWV6RKWUOSF08.png&filename=Screen Shot 2021-12-06 at 2.06.56 PM.png)
Welcome to our Split Flap Assembly and Design Instructable! Split flap displays are a fun, and quirky way to display messages in alphanumeric text. Since the instructions here are pretty lengthy, we've grouped the steps into 4 major categories:
- Electrical Assembly
- Hardware Engineering
- Character Lettering Design
- Software Programming
Supplies
Materials for the Electrical Assembly (per split-flap unit):
1x Arduino nano (every) 1 https://www.amazon.com/dp/B07VX7MX27
1x Perfboard 24x18 holes (5x7cm) https://www.amazon.com/dp/B07LF78ZY3
1x Stepper motor Nema 17 with step angle 1.8deg https://www.amazon.com/dp/B094CQ4DBQ
1x A4988 Stepper Motor Driver with Heat Sink https://www.amazon.com/dp/B07BND65C8
1x Male header pins 4-pin https://www.amazon.com/dp/B0774VBJ3J
2x Female header pins 15-pin
2x Female header pins 8-pin
2x Female header pins 3-pin
2x Female header pins 2-pin
3x Female header pins 1-pin
1x Hall Effect Sensor https://www.amazon.com/dp/B07QS6PN3B
3x colors 22AWG Solid Core Wire https://www.amazon.com/dp/B07TX6BX47
4x TOTAL (for up to 8 split-flaps) Wire Nuts https://www.amazon.com/dp/B01MPXUEPO
2x TOTAL (for up to 8 split-flaps) 5KOhm resistors https://www.amazon.com/dp/B07HDFN3NV
Materials for Hardware Design (per split-flap unit):
2x Wooden Housing Case
1x Front Acrylic Panel
1x Acrylic Laser Cut Side Panel
1x Acrylic Laser Cut Right Wheel
1x Acrylic Laser Cut Left Wheel
1x 3D Printed Hub
1x 3D Printed Motor Mount
50x Split Flap
1x Acrylic Spring Holder
1x Aluminum Spring Holder
1x Spring Tin Strip
1x Motor Coupling + its screws
1x Magnet (for hall effect sensor)
4x #4 Washer
4x 4-40 Nut
4x 4-40 Bolt
11x #4 Wood Screws
4x 2/56 Nut
2x 4-40 Nut
2x #4 Washer
2x 4-40 x 1/2” screw
2x 4-40 x 3/8” screw
4x 2/56 x 3/8 Screws
4x 8mm M3 Screw
Materials for Character-Lettering Design
2x sheets of vinyl per 50-flap split-flap in the colors that you want the lettering to appear in
1x Silhouette Cameo
1x cutting mat
Electrical Assembly - Supplies
![assembly-0-electrical-materials.png](/proxy/?url=https://content.instructables.com/F60/O3AU/KUZJ12MX/F60O3AUKUZJ12MX.png&filename=assembly-0-electrical-materials.png)
![assembly-7.png](/proxy/?url=https://content.instructables.com/FX6/PWHY/KUZJ12N6/FX6PWHYKUZJ12N6.png&filename=assembly-7.png)
Here is an image containing all the supplies you will need to assemble the electrical wiring. See the supplies section above for a comprehensive list of all the needed components and links to purchase each
Electrical Assembly 1
![a4988 and individual microcontrollers v1.0.png](/proxy/?url=https://content.instructables.com/FMF/8K36/KV2I6D01/FMF8K36KV2I6D01.png&filename=a4988 and individual microcontrollers v1.0.png)
![assembly-1.jpg](/proxy/?url=https://content.instructables.com/FXQ/DHDS/KUZJ12MZ/FXQDHDSKUZJ12MZ.jpg&filename=assembly-1.jpg)
The diagram is what we will be building today. Feel free to build it your own way or follow our detailed instructions below!
First, solder wires to the hall effect sensor. Make sure the sensor is flipped the right way (when the face with chamfered edges is facing you, the wires are power, ground and signal left to right)! Add heat shrink for insulating the wires.
Electrical Assembly 2
![assembly-2.png](/proxy/?url=https://content.instructables.com/FU4/24JS/KUZJ12N0/FU424JSKUZJ12N0.png&filename=assembly-2.png)
Cut the header pins down to the following lengths:
1x male 4-pin
2x female 15-pin
2x female 8-pin
2x female 3-pin
2x female 2-pin
3x female 1-pin
Electrical Assembly 3
![assembly-3-top.png](/proxy/?url=https://content.instructables.com/FRY/XO9G/KUZJ12N2/FRYXO9GKUZJ12N2.png&filename=assembly-3-top.png)
![assembly-3-bottom.png](/proxy/?url=https://content.instructables.com/F5B/F7KS/KUZJ12N1/F5BF7KSKUZJ12N1.png&filename=assembly-3-bottom.png)
Place and solder components to perf board according to our design here. Your perf board's coordinates might not exactly match our spreadsheet, so be sure to still count the coordinates!
(For assembly, use the Top View; for soldering, use Bottom View, flipping around a left-right axis)
- Plug 2 female 8-pin into the driver
- Plug 2 female 15-pin into Arduino
- Put Arduino onto the board and solder the pins to the board (Bottom View, solder D2-16, J2-16)
- Put driver onto the board and solder the pins to the board (Bottom View, solder M7-14, R7-14)
- Put 1 male 4-pin onto the board and solder (Bottom View, solder S9-S12)
TIP: Unplug the Arduino and driver to better solder the small pins
TIP: For the small pins, tape the non-solder side before flipping it over and soldering. - Put the 2 female 3-pin onto the board and solder them (Bottom View, solder K11-13, L11-13).
- Next, do the 2 female 2-pin (B8-9, C8-9), and 3 female 1-pin (C13, K12, K14).
Electrical Assembly 4
![assembly-4.jpg](/proxy/?url=https://content.instructables.com/FGM/OSNV/KUZJ12N3/FGMOSNVKUZJ12N3.jpg&filename=assembly-4.jpg)
Wire the 4 wires from Top View, A->A (K13->S11), B->B (D16->S4), C->C (B13->S10), and D->D (K8->T10).
Electrical Assembly 5
![assembly-5.jpg](/proxy/?url=https://content.instructables.com/F1A/TQVL/KUZJ12N4/F1ATQVLKUZJ12N4.jpg&filename=assembly-5.jpg)
Following the Bottom View design, bridge neighboring cells in the same color in the diagram with solder.
Electrical Assembly 6
![247587999_1880035518856726_304174770725753843_n.png](/proxy/?url=https://content.instructables.com/FWA/IJZB/KUZJ16O7/FWAIJZBKUZJ16O7.png&filename=247587999_1880035518856726_304174770725753843_n.png)
Plug the Arduino and driver back into the board. From a top view when the Arduino is on the left and the driver is on the right, the Arduino's USB port should be facing up, and the driver's silver phillips screw knob should be facing the other way (you can check against the picture).
If you haven't already, now's a good time to stick the heatsink on the central chip of the motor driver.
Plug motor and hall effect sensor into the perf board. Make sure the red motor wire faces the USB.
Electrical Assembly 7
![assembly-7.png](/proxy/?url=https://content.instructables.com/FOH/45LG/KUZJ12PB/FOH45LGKUZJ12PB.png&filename=assembly-7.png)
Connect all of your boards together with two wires for I2C communication by plugging male-male jumper wires (or lengths of solid core wire) into the 4 header pins in a 2x2 square next to the Arduino. The two pins on the side closer to the USB port are SDA pins, the two farther are SCL pins. There are two of each so you can chain the boards together. And remember that somewhere on the I2C bus you will need pullup resistors (approximately 5KOhm) connecting each wire to 5V.
Electrical Assembly 8
![IMG_8443.png](/proxy/?url=https://content.instructables.com/FPB/HKL7/KUZJ13IW/FPBHKL7KUZJ13IW.png&filename=IMG_8443.png)
Connect all boards to the power supply, we found wirenuts useful here.
Electrical Assembly 9 [FINAL]
![Screen Shot 2021-10-19 at 10.28.18 AM.png](/proxy/?url=https://content.instructables.com/F1P/RX9F/KUY3KCXC/F1PRX9FKUY3KCXC.png&filename=Screen Shot 2021-10-19 at 10.28.18 AM.png)
Admire your handiwork! Here's what our final product looked like!
Hardware Engineering
![Material lIst.png](/proxy/?url=https://content.instructables.com/FHO/2DTU/KV2I5XQ4/FHO2DTUKV2I5XQ4.png&filename=Material lIst.png)
![Split Flaps Hardware Engineering](/proxy/?url=https://content.instructables.com/FBI/EUFX/KV2I5Y2B/FBIEUFXKV2I5Y2B.jpg&filename=Split Flaps Hardware Engineering)
![Split Flaps Exploaded View Animation](/proxy/?url=https://content.instructables.com/FT1/2UVO/KV3TEGC8/FT12UVOKV3TEGC8.jpg&filename=Split Flaps Exploaded View Animation)
Now, we will start creating the housing for your split flaps! Make sure to prepare these items before starting. Refer to this video as you go through all the steps for the "Hardware Engineering" of this tutorial.
Hardware Engineering 1
Attach the 3D Printed Hub with the Acrylic Laser cut Left Wheel using four #4 Wood Screws (make sure the row of holes are oriented away from the Left Wheel).
Hardware Engineering 2
Attach the 3D Printed Motor Mount with Stepper Motor using four 8mm M3 Screws.
Hardware Engineering 3
Attach the 22AWG Solid Core Wires and Hall Effect Sensor with the Stepper Motor (Make sure that the narrower side of Hall Effect Sensor is facing out/ towards the magnet).
Hardware Engineering 4
Attach the Motor Coupling with the Acrylic Laser cut Right Wheel using four sets of 4-40 Bolts, #4 Washers, 4-40 Nuts.
Hardware Engineering 5
Attach the Motor Coupling with the Stepper Motor.
Hardware Engineering 6
Glue the magnet onto the inner wall in the center of 3D Printed Hub (Make sure you have tested out the magnet beforehand and have glued it onto the correct side).
Hardware Engineering 7
Attach the Right Wheel structure with the 3D Printed Hub using four #4 Wood Screws.
Hardware Engineering 8
Attach Split Flaps by constantly loosening/tightening different screws in order to slide in the flaps (Make sure to have the first split-flap align with the magnet, so it’s easier to calibrate later) After all the flaps are in place re-tighten all the screws
Hardware Engineering 9
Attach the Acrylic Laser cut Side Pane onto the Left Wheel of the Structure by first sliding all the wires through the cut-out of the Side Panel, then attach by using three #4 Wood Screws.s
Hardware Engineering 10
Attach the Assembled Perf Board onto the Side Panel using four sets of 2/56 x 3/8 Screws, 2/56 Nut.
Hardware Engineering 11
Attach 22AWG Solid Core Wires and Hall Effect Sensor wires onto Perf Board and wire management.
Hardware Engineering 12
Sandwich the Spring Tin Strip between Aluminum and Acrylic Spring Holders using two 4-40 x 3/8” screws
Hardware Engineering 13
Attach the Spring Structure onto the Side Panel of the main structure using two sets of 4-40 x 1/2” Screws, #4 Washers, 4-40 Nuts
Hardware Engineering 14
Now one full structure of Split Flaps should be done. Spin the structure, and adjust the Spring if needed.
Hardware Engineering 15 [FINAL]
Attach the Split Flats structure with the rest. Done!
Designing the Split-Flap Lettering (All 4 Steps)
![BrainStormingFonts.PNG](/proxy/?url=https://content.instructables.com/FP6/WPQ9/KUY3KF82/FP6WPQ9KUY3KF82.png&filename=BrainStormingFonts.PNG)
![One Split Flap.png](/proxy/?url=https://content.instructables.com/F1E/MH8A/KUY3KFGT/F1EMH8AKUY3KFGT.png&filename=One Split Flap.png)
1. Prepare vinyl in the color and finish you’d like your letters to be in.
For our project, we ordered white and aqua vinyl with glossy finish. Our vinyl.
2. Select a font for your split flaps and scale the letter size so that it will fit on a single split flap.
For reference, you can see the Adobe Illustrator File that we used with every character already scaled and vectorized for the cameo.
To scale properly, make sure to measure the dimensions of your own flaps so that your characters are sized accordingly.
Feel free to use our font (The Adobe Illustrator files we used are below and ready for vinyl printing!) or make your own! Notice how every character is divided in half to account for how the characters will appear on the split-flap.
3. Cut the characters on vinyl using a Silhouette Cameo.
NOTE: Regular laser cutters will release toxins when cutting through vinyl, so please use an electronic blade cutter like the Silhouette Cameo.
4. Stick the cut vinyl onto the split-flap.
Every split-flap will get half a character (see image above).
While sticking them on, keep in mind that two adjacent sides of each split-flap form one letter. See our video as a guide to help you out!
Coding the Program
![Screen Shot 2021-10-19 at 10.26.15 AM.png](/proxy/?url=https://content.instructables.com/FE2/JR2O/KUY3KCR0/FE2JR2OKUY3KCR0.png&filename=Screen Shot 2021-10-19 at 10.26.15 AM.png)
.High level explanation of code, what leader does, what follower does
Our system is controlled by a single leader arduino which sends commands and receives updates from several follower arduinos which interface directly with a corresponding stepper motor setup.
The leader handles communication between the different follower arduinos and assigns specific commands to each follower arduino. The leader arduino is not directly connected to any stepper motor, and solely facilitates broader inter-follower communication and coordination.
Follower arduinos either wait in place, calibrate using the hall sensor, search for a specific letter, or spin based on their current state. After receiving commands from the leader arduino, follower arduinos execute actions based on their given command then update the leader arduino when actions are completed.
Leader Code Overview
The leader arduino can either initialize (under Initializing state in LeaderState) to set up communication between the leader arduino and all follower arduinos, calibrate each follower (under CalibrateFollowers state) by sending a CALIBRATE command to each follower, update state and sends the command to spin to a specific letter under the SendingReceiving state, or do nothing under the DoNothing state.
Follower Code Overview
Changing options and modifications
Finishing Up!
![Screen Shot 2021-12-06 at 2.06.56 PM.png](/proxy/?url=https://content.instructables.com/FDD/9EMB/KWUOSEBX/FDD9EMBKWUOSEBX.png&filename=Screen Shot 2021-12-06 at 2.06.56 PM.png)
![Working Split-Flap Display!](/proxy/?url=https://content.instructables.com/FGY/LYX4/KWUOSESF/FGYLYX4KWUOSESF.jpg&filename=Working Split-Flap Display!)
Pictured above is our final product! And a video of it working to display a poem we wrote :)