Tag Archives: equatorial

3d printed equatorial platform

Here is the platform in operation. Notice the 3d printed phone holder attached to the eyepiece. I also use a DSLR with a 2x barlow.

The north segments are the only potentially unique part of the design. Inspired by the common Vertical North Sector (VNS) design, these are “bent” elliptically so they contact the drive wheel in the same point for the complete rotation. This was an attempt to prevent the rotation rate from varying with time. I haven’t done the math to see how much this matters and it seems there’s other errors that might be more significant in my build. The bottoms of the sectors are the surface of a cone.

The electronics are very simple. I bought a 1:100 planetary gearbox stepper motor from Amazon, the Pololu Tic T834 Stepper Motor Controller, and the Arduino Nano with Bluetooth Low Energy (BLE). The Bluetooth allows me to precisely adjust the velocity command during observation. All of this is powered by 4 AAA batteries. The batteries seem sufficient for over 5 hours of operation. AA batteries would probably be a little better.

For friction, the drive wheel is wrapped in a rubber end cap with the end cut off. The cap is 22mm and I sized the wheel to be 23mm to give it enough friction not to slip off. I also printed a wall at the outside edge of the drive wheel to retain it from getting extruded out. The wheel is also slightly cone shaped because this is actually a conical drive.

The south bearing is a simple pivot angled to point along the rotation axis (towards the north star) of the platform. I’d like to make the platform more square, but that would require a more complex south bearing and I just wanted to see if the idea would even work first.

Pictures taken using the platform

December 22, 2020 Saturn and Jupiter Conjunction
Pluto — October 1, 2020
Dumbbell Nebula — September 21, 2020
Ring Nebula — August 18, 2020
Andromeda — September 10, 2020
Omega Nebula — 20200904
Mars — September 21, 2020
Saturn — September 3, 2020
Jupiter — August 20, 2020