For quite some time I was considering upgrading my standard EQ6 with better electronics and mechanics.
As any form of commercial upgrade was never an option for me (a matter of principle
) I decided to do it myself..
The first step was Darren's firmware, I did this last year and now I have GoTo functionality.. (with the help of laptop, running CdC)
This time, it was the steppers and gearboxes.
I could not find Konrad gearboxes (most popular choice for many, it seems) so I decided to design my own.
Also, I wanted to end up with such a system that will tolerate much higher slewing speed.
And I wanted to have everything inside existing housing (so external timing belt reduction, an excellent choice from the backlash and PE point of view) was also out of the equation.
The design I adopted is as follows:
1) 200s/rev steppers from 5 1/4" floppy drive
2) Two-stage gearbox (1/4 each, overall reduction 1/16)
3) miniature ball bearings on all shafts
4) re-using the existing gears for worm coupling.
Steppers had only 5 wires, so I opened them and added 6th (so I ended up with two isolated coils with middle terminals).
The gear pairs are all the same:2 x 20 and 80 teeth gears and they all came from my junk-box..
This configuration is also compatible with Bartel's software.. which I know will work perfectly (from the experience with my dobson).
The overall reduction of such motor-gearbox assembly is 66.6666 (the original was 132.8125)
The final resolution (with micro-stepping) is 0.0703 arcsec/step [original was 1.1294arcsec/step, or 0.5647arcsec/ustep (Darren's mod)]
The result (not completed yet) is on the pictures below.
Now the only couple of things remained to do is to assemble the RA gearbox, to mount everything inside the mount and to see how it works :-) .
I will post the results when I do all this. It will not do much for 8min period (worm) but the higher frequency components will be eliminated or sufficiently reduced, as well as backlash.
The next step of this project will involve a software change:
- Darren's code has a problem with 24x slewing speed.
- this is not quite fast enough
and
- it does not support acceleration (not really required for 16x slewing), but absolutely required for anything faster, considering 25kg of telescope and counterweight, loading the mount.
Of course, in a course of things I may decide to stick with Mel Bartels' solution.
In that case, I will have to build the new drivers for motors (to fit inside the mount cavity).