Parametric Equatorial table for Dobson telescope

This is an easy way to build a DIY equatorial table. See it running on youtube: https://youtu.be/ka9uXJvbwiM

An equatorial table shall be adapted to the telescope you intend to use (size and mass) and to your location (latitude of observations).
This is the reason why one cannot find a ready to build plan of an equatorial table.
I decided to build mine to adapt a vintage SkyWatcher 1000x200 Newton telescope. Rather than doing a one shot design, I designed it to be fully parametric and customizable according to your needs. The design should work for latitudes between 30 and 50 degrees, I'm located in South of France hence a default 43.5° latitude !

Parametrization is based upon an Openscad script that will do all the job to generate the Vertical (curved) North Segments.

You just enter few parameters into the script, run it to generate the VNS :
- latitude where you intend to set your Dobson
- mass of the tube
- mass of the Dobson mount
- estimated mass of the upper plate of the platform (the rotating part)
- radius of the Dobson mount (from center to center of PTFE pads)
- duration of observation (best between 60 and 80 minutes)

You can also specify to the script if you want the metal rails or not to reinforce the PETG VNS.

Et voilà, you get the VNS ready to assemble and several computed dimensions that will help you to buid the wooden parts.

The South bearing is a simple ball joint bearing. It can be screwed to trim its length according to the latitude and level the upper plate.

Everything is mounted on ball bearings (the standard skate ones...) and they are rolling metal on metal.

Motorization is performed by a cheap 28BYJ-48 stepper motor modded to 2 phases- 4 wires.
The motor directly drives a worm screw carying a 3D printed carriage actuating a rod connected to the table by a 3mm rod and 2 ball joints.

Speed control is performed by an arduino board (I used an ESP32). The software includes all the equations to control the carriage speed in order to drive the table to compensate the Earth rotation.

The total cost of all the hardware is < 50€.

Accuracy will depend on how well you'll be able to assemble and align the parts, but I can say it works pretty well for observations, Saturn was kept close to the center of the eyepiece during one hour ! My feeling is that every Dobson for visual observation should have its equatorial table :-)