Tommy's Star Tracker - for Telescope Astrophotography by tommyent

Last crawled date: 3 years ago

A 3D printed star tracker mount for visual astronomy and astrophotography!
This design is based on SimonRob's Equatorial Mount for DSLRs (https://www.thingiverse.com/thing:4365068), but it's been upgraded to handle smooth tracking on a lightweight telescope setup. A huge thanks to him for laying the groundwork, and I highly recommend checking his thing out for a great set of build instructions.
Note that I also used Trigubovich's Compact planetary gearbox (https://www.thingiverse.com/thing:2114390) , but couldn't get the remix connection to work; I'll see if I can fix that.
Also, don't forget the matching latitude base and the 3D printed counterweight!https://www.thingiverse.com/thing:4776560https://www.thingiverse.com/thing:4755514
Parts List:
a ball head mount
a Nema 17 motor
electronics to drive the motor (I used an arduino)
a 200mm GT2 belt
a 20T GT2 pulley
Two R8-2RS bearings (1/2" x 1 1/8" x 5/16")
One 623ZZ bearing (3mm x 10mm x 4mm)
Four M3 40mm screws for the Nema motor
an M5 bolt for the planetary gear output
a bunch of short M3 bolts and nuts for assembley
a 1/2" OD tube (I had aluminum on hand, but it's a common size for rigid copper)
a 3/8" threaded rod and nuts for the counterweight (or metric equivalent should be fine)
The reduction ratio is 1:17 (1:4 at the planetary gear and 1:4.25 at the pulley)
Telescope should rotate every 23.9344 hours
after the 1:17 reduction that's 1.4079 hours
that would equal 5068.47 seconds
Nema has 200 steps or 6400 microsteps (at 32 microsteps)
5068.47 sec / 6400 microsteps
0.7919485 seconds per microstep
If microstepping at 32, you should have one step every 0.7919485 seconds.
I am just getting this out there for people now, but I will update this with build instructions soon. Here is the code:
// TOMMY'S STAR TRACKER
const int stepPin = 9; // Set the stepping pin to pin 9
const int dirPin = 8; // Set the direct pin to pin 8
define DELAY 791.95 // This is the delay in between steps in milliseconds
void setup() {
pinMode (stepPin, OUTPUT); // Set stepPin as output
pinMode (dirPin, OUTPUT); // Set dirPin as output
digitalWrite (dirPin, HIGH); // Set the direction to clockwise
}
void loop() {
digitalWrite (stepPin, HIGH); // Start a stepper pulse
delay (DELAY); // Wait
digitalWrite (stepPin, LOW); // End a stepper pulse
delay (DELAY); // Wait and repeat
}