A 3D Printed Seven Segment Electro-Mechanical Single Motor Driven Display.
Introduction: A 3D Printed Seven Segment Electro-Mechanical Single Motor Driven Display.
Via followers of mine I've received a number of links to electro-mechanical seven segment displays created from cardboard or Legos using quite a few servos and/or motors to simulate a seven segment LED display, and most if not all were not quite what one would consider to be a "low profile" design. I was then challenged by one follower to attempt to create a low profile design of an electro-mechanical seven segment decade counter driven by a single motor, and "A 3D Printed Seven Segment Electro-Mechanical Single Motor Driven Display" is my answer to the challenge.
In my design, an Adafruit ESP32 drives an inexpensive stepper motor and driver, which in turn drives two slotted cams (one controlling the A, B, F and G segments, and a second controlling the C, D and E segments) such that the model counts from 0 through 9 repeatedly (a decade counter) via a single stepper motor. Seven "slides" follow specific cam slots in order to swing the seven segments in and out of view, and a mere 3.5mm deflection of a slide results in a 90 degree movement of its respective segment.
I plan on expanding this design to create a large format hours and minutes clock.
As usual I probably forgot a file or two or who knows what else, so if you have any questions, please do not hesitate to comment as I do make plenty of mistakes. Designed using Autodesk Fusion 360, sliced using Ultimaker Cura 4.10.0, and 3D printed in Ultimaker PLA on Ultimaker S5s.
Step 1: Parts.
I acquired the following parts:
* One Adafruit Feather ESP32 board.
* One "6PCS 28BYJ-48 Stepper Motor Kit".
* Four "uxcell 6700-2RS Deep Groove Ball Bearings Z2 10mm x 15mm x 4mm Double Sealed Chrome Steel".
* One USB power supply with connector compatible with the USB connector on the ESP32 board.
* One 36" length of 1.9mm music wire.
I 3D printed the following parts at .15mm layer height, 20% infill and no supports:
* Two "Axle, Gear, Cam.stl".
* Fourteen "Axle, Segment.stl".
* Two "Bolt, 4mm.stl".
* Six "Bolt, 8mm.stl".
* One "Cover.stl".
* One "Face.stl".
* One "Gear, Cam A, B, G, F.stl".
* One "Gear, Cam C, D, E.stl".
* One "Gear, Cams, Drive.stl".
* One "Rear.stl".
* Seven "Segment.stl".
* One "Slide A.stl".
* One "Slide B.stl".
* One "Slide C.stl".
* One "Slide D.stl".
* One "Slide E.stl".
* One "Slide F.stl".
* One "Slide G.stl".
This mechanism is a high precision print and assembly using at times very small precision 3D printed parts in confined spaces with highly precise alignment. 1014
I 3D printed all parts using the Ultimaker Cura 4.10.0 "Engineering Profile" on my Ultimaker S5s, which provides a highly accurate tolerance requiring minimal if any trimming, filing, drilling or sanding. However, prior to assembly, I still test fitted and trimmed, filed, drilled, sanded, etc. all parts as necessary for smooth movement of moving surfaces, and tight fit for non moving surfaces. Depending on your slicer, printer, printer settings and the colors you chose, more or less trimming, filing, drilling and/or sanding may be required to successfully recreate this model. I carefully filed all edges that contacted the build plate to make absolutely certain that all build plate "ooze" is removed and that all edges are smooth using small jewelers files and plenty of patience.
This mechanism also uses threaded assembly, so I used a tap and die set (4mm by 1 and 8mm by 1.25) as required for thread cleaning.
Step 2: Assemble the Face.
To assemble the face, I performed the following steps:
* Using a handheld rotary tool with a cutoff blade, I cut seven 10mm lengths of 1.9mm music wire then removed the bur from the one end and rounded the other end of each of the seven pins. 632