Parametric Equatorial Table Or Platform For Dobson Telescope 3D Printer Model Free Download

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Summary

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

See the results on the Moon and Jupiter: https://www.youtube.com/watch?v=I6fJBA_TYC4

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 55 degrees (at least), 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.

[OLD 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.]

EDIT: I changed the drive system of my 3D printed equatorial table.
Previous concept was with a lead screw, it had some drawbacks mainly backlash and software complexity.
This new concept uses:

a planetary geared stepper motor (1:51) which provides plenty of torque
a wire
a spring
a cylindrical North sector only used to guide the wire
See it on youtube: https://www.youtube.com/watch?v=mnKlnrRpf_w

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 :-)

EQ_table.xlsx	156.0KB
ESP32_EQ_table_2cores.ino	11.4KB
ESP32_EQ_table_2cores_wire.ino	11.5KB
NEMA-PG-mount.scad	857.0B
NEMA-PG-mount.stl	131.5KB
table-eq-bearing.stl	708.3KB
table-eq-rotule.scad	10.2KB
table-eq-rotule.stl	1.0MB
table-eq-rotule_nut.stl	2.3MB
table-eq-wire.scad	14.4KB
table-eq.scad	11.6KB
table_EQ.pptx	1.9MB
telescope_motor.scad	14.3KB
telescope_motor1.stl	147.3KB
telescope_motor2.stl	87.6KB
telescope_motor_nut.stl	2.2MB
telescope_motor_plaque.stl	79.8KB
Thread_Library.scad	11.1KB

Parametric Equatorial Table Or Platform For Dobson Telescope 3D Printer Model

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