Reworked Mechanical Planetarium

When I first received my Ender 3 v2, my wife sent me a link to the mechanical planetarium as a joke.  But I actually tried to print it and became disappointed when I discovered that I could not manage tolerances well enough for the entire assembly.  I forgot about it for a while, with a partially completed planetarium being a trophy to the poor quality printer.  About a year later, a coworker convinced me to buy a Prusa MK4, which turned out to be so much better than I ever expected vs the Ender 3.  So I came back to this only to discover that Damada42 had added a stepper motor.  I bought the electronic parts and got to printing, and the first attempt worked, but not well.  So I started tweaking, and rebuilt it more times than I care to remember.  I ended up with 16 changed parts in my version.  After making 3 of these, I'm ready to release this remix to the public. 

Some pointers on printing and building:

• Use ironing on all surfaces touching rotating parts, like the top of an idler gear, or all parts stacked on the tower.  In Prusa slicer, right click → Add Setting → Ironing.  Check all boxes and select “Topmost Surface Only”.  This will work for most parts.  Some require adding a modifier to a specific area of a part to selectively iron areas.  
• Use a knife and fine grit sand paper taped on glass (guaranteed flat surface) to further smooth surfaces where able.  
• Lubricate rotating parts.  I used small amounts of super lube because I had it on hand.  
• Lightly sand the main drive shaft.  
• Reem holes with a slightly larger drill bit

I printed this on my Prusa MK4 with input shaping turned on using the mostly default 0.20mm STRUCTURAL print settings.  My changes were:

• 3 perimeters. 
• Check “Avoid crossing perimeters”. 

I printed almost the entire model with PLA, with the exception of the 28ByJ48_Axis.  The stepper motor does get warm, and printing this file solid and out of PETG fixed my issues.  

Electronics:

After discovering that a 5V stepper motor didn't have the torque to really do this justice, I decided to up that to 12V.  A 5.5x2.1mm barrel jack is needed as well as a buck converter to step down to 3.3V.  The buck converter has a trim pot that will need to be adjusted to output 3.3V.  This requires a multimeter.  The button is somewhat loose in its slot, and shimming with a folded piece of paper solves this issue.  Hot glue works wonders for keeping the ESP8266 in place. 

EDIT: I forgot to upload the code initially, and can't find my .ino file.  Use Damada42's planetarium.ino.  Just remember to use the Arduino IDE to edit the wifi/AP settings first.  Follow the instructions on the Amazon page to setup the IDE to talk to the board.  The most important thing is to install the appropriate drivers:

CH340 Drivers for Windows, Mac and Linux

This link will save you hours of frustration.  

To satisfy the ESPAsyncWebServer.h dependency, install ESPAsyncHTTPUpdateServer by Mohammad Mahdi Nazari with all dependencies.  As of 12/2/2024, this compiles and uploads.

• Uses 12V to power the stepper motor for more torque.  Pretty much any 12V wall wart that outputs more than 1A will work.  
• Power input changed to 5.5x2.1mm barrel jack.  
• Base plate reworked to accommodate buck converter to step down from 12V to 3.3V for electronics.  eBoot Mini MP1584EN DC-DC Buck Converter Adjustable Power Supply Module 24V to 12V 9V 5V 3V (12 Pack)
• Main drive shaft is now keyed on both ends.  It will stay together if you pick up the entire assembly via the sun cap. 
• Tweaked the width of the tabs on the idler arms to minimize precession. 
• Sun peg no longer tries to lock into the base plate.