I'm for over 30 years a mechatronics technician and for a few years a amateur astronomer. Actually, I have been involved in astronomy since my childhood, but after a long time break, I have found my way back to this beautiful hobby.
I have now used my craftsmanship and specialist knowledge and have built my own OnStep GoTo controller for my SkyWatcher EQ5. I'd like gladly to report about it here in this forum.
I was in point of fact to build a simple tracker for my EQ5, but I quickly became aware of Howard Dutton's OnStep project in my search for a simple solution. After registering with the OnStep project group and reading the articles carefully, I decided to build myself an OnStep. Since I was looking for a simple, compact variant in my own impatience and wanted a finished GoTo controller quickly, I decided to reproduction the MiniPCB, based on the Teensy 3.2.
Here is my finished configuration for the stepper motors and the power transmission to the worm gears after some experiments:
NEMA 17 Bipolar Stepper 0.9deg (400 Schritte/Rev) 1,68 A 44 Ncm (62.3oz. in) Motor
GT2/2GT pulley 12 Teeth 5.0mm Bore with 6mm Width Belt for the motor shafts.
GT2/2GT pulley 48 Teeth 6.0mm Bore with 6mm Width Belt for the worm shafts on the EQ5.
This results in a ratio of 4:1 only for the drive. With the worm gear ratio of 144:1 results in a total ratio of 576:1. This results on 1/16 micro-steps for both axis a resolution of 10240 Steps Per Degree. The Brackets for the Nema 17 stepper motors on the EQ5 mount, I have found this on Thingiverse.com website.
I put a little video about the production process on Youtube.
Later I made the OnStep Smart Hand Controller with a little display. Although the OnStep is actually designed for operation with a smartphone or a tablet, I think that operation with the Smart Hand Controller is the better option.
I hope, you enjoyed my small contribution about my replica of the Onstep.
Thank you in advance.
Kind regards from Austria.
Edited by Roman167, 17 June 2019 - 08:36 AM.