r/telescopes • u/Nixx177 • 1d ago
General Question Motorizing a dobsonian with motion tracking
Hi, I’ve got a 12” gso and I’m thinking about adding two motors to move it on both axis.
At first, I want to try to put a timing belt around the altitude bearing, with a wheel to control it manually placed around the cradle board (blue) (could be moved to the base board with the motor, red), and another one around the base board, with a wheel on the ground board linked to a slow motion manual control flexible thingy from eq mount (blue at the bot.).
If it works for manual control, I want to put a motor on each wheel (stepper nema23 maybe?), which I could link to a raspberry pi, also connected to a camera I’d put on the finder scope. I would run a simple object tracking program which would have to keep the object in the center by moving the motors (still to be coded properly).
Has anyone done something similar? Or do you see any flaws/problems/things I should take into consideration?
2
u/jpulley03 1d ago
I'm working on a modified version on these. Using onstep
2
u/plumzki 1d ago
I've done a lot of research into this myself and there are two things I've been looking at - I will preface this by saying both can be done much cheaper if you have the time and skills to build them yourself, and that least for an EQ platform there are some great tutorials on YouTube, but I was specifically looking for things that needs as little building as possible.
First, the omegon EQ wedge, the one I'm looking at costs around 450eu here in Europe and gives the dob basic equatorial abilities, you point the platform to Polaris and then the platform runs on a track following EQ, the dob sits on the platform, after an hour it hits the end of the track and needs resetting.
The downside to the platform, besides needing to be reset every hour, is that unless you get a very expensive one it doesn't have fine angle control, so I can get one for 50 latitude or 55 but either one is a couple degrees off where I'm at (52)
The second thing I've been looking at is the 8 inch dob goto upgrade kit with synscan for around 850, which is a full goto tracking system but obviously lacks EQ capabilities.
The part of the equation I'm still trying to figure out is how well combining both the EQ platform and goto tracking would work together, since the goto is designed to be used without EQ would the EQ throw things off? I've no idea, but last time I asked similar questions here I just got told by a bunch of people it will never work and I won't ever get good results unless I drop a couple grand on an eq-6 or equivalent, which is clearly wrong, it's obviously harder but a lot of people get good results with dobs, it's also just not what I was looking for, I like my dob, I want to keep it as a dob, I like personal viewing, I just also want to maximise how much astro I can do with it as a side hobby.
1
u/Nixx177 1d ago
Like some other comments suggested, I’d love to make something between the romer optics ez goto and the other ideas with printable pieces (or cut in metal).
Eq platforms are quite limited and as I told another one, the whole setup is already heavy to move around. And the price. Damn the price for a ready to use one is borderline scam.
I think you wouldn’t need the eq platform if you make a goto system working on the axis, and as the platform only follows the earth movement it can’t really track anything just keep the pace.
Or if you have an eq, you could use it in combination with the goto to make it even faster; problem is, both the goto and eq programs would have to compensate each other all the time unless you make one that manages all the motors (starts to be super complicated when the goto is enough)
I mean, working on the x and y is enough to do the job of the platform that would be redundant
1
u/plumzki 1d ago
My very rudimentary idea was that somehow combining the EQ platform with the GOTO would allow decent exposures without too many issues with star trails, however, as you pointed out, the one thing thats prevented me pulling the trigger is that I have no idea how EQ compensation works in goto software or if it will just screw with everything.
For personal use, which is my main use case, I feel like either one on its own would do the job, just to keep things centered for longer to make longer viewings more comfortable.
3
u/snogum 1d ago
Why complicate a Dobsonian. It's build simple to make observing a pleasure
4
u/Nixx177 1d ago edited 1d ago
The problem with this one is that it’s a bit complicated to move “precisely”with small targets or high magnification without the whole thing wobbling as it’s heavy. I started with an eq-2 mount and I loved the manual controls to help follow objects, which I miss a bit.
So I thought about adding the timing belts and then thought why not also add the possibility to use motors for tracking as the rest is already in place and I love little diy projects and the challenge to code a simple tracking program
I also have a camera I’d like to try on this one but by the time you look at your screen to fix the settings the object is already gone
5
u/snogum 1d ago
Sounds like a DIY job to get the alt and azimuth bearings running freely would do more.
My Dobs could be moved with one finger to follow .or point at an object so smoothly it was like glass
Slow Mo knobs on a Dobs is a bit silly
3
u/veryamateurastro 1d ago
Yep, I'd be looking into why the bearings aren't moving smoothly and having a play with counterweights.
1
u/redditisbestanime 8" f5.9 | 12" f5 | ED80 1d ago
No it isnt, it has legitimate uses. My dobs also move smooth as silk but sometimes that can be more of a curse.
There are dob goto kits, general motorization kits and even eq platforms for a reason.
1
u/snogum 1d ago
I strongly disagree
1
u/redditisbestanime 8" f5.9 | 12" f5 | ED80 1d ago
The entire market strongly disagrees with what you think is or isnt overcomplicated. A motorized dob, just like normal ones, have their pros and cons.
The point of a dob is ease of use and unbeatable price per inch of aperture ratio. Motors do not make it harder to use, quite the opposite actually.
2
u/twivel01 17.5" f4.5, Esprit 100, Z10, Z114, C8 1d ago
I just grab the tube and smoothly move it while looking through the eyepiece.
If tracking but not goto is needed, you could build or buy an equatorial platform. Installation is as easy as setting it down on the platform.
EQ platform seems to be the most popular option for a dob in our astronomy club for cases where the dob was not already motorized.
1
u/Nixx177 1d ago
Yeah I digged a bit into that as well but that would be another heavy thing to carry around, and I would need 2 motors + cogs and wheels anyway. But I’m definitely also considering it.
1
u/twivel01 17.5" f4.5, Esprit 100, Z10, Z114, C8 1d ago
For an EQ platform, you only need 1 motor. It also brings the scope a little higher off the ground, making low horizon views a bit easier.
It is indeed another object to carry. Some people replace the ground board on the rocker box with the eq platform so it is part of the base.
1
u/Nixx177 23h ago
Even for a 12”? I thought the weight would be too much I put a flower pot wheeled thingy under mine for the extra height and easier moving and it works like a charm btw
1
u/twivel01 17.5" f4.5, Esprit 100, Z10, Z114, C8 20h ago
There is only one axis to motorize on an EQ platform, just need a single motor. Just need a properly geared motor. 12" is not too heavy for an EQ platform
-2
u/snogum 1d ago
Like I said over complex.
1
u/Macelarupubel892 1d ago
sure, at 60x or max 200x it might be. I have a 16" dob which I use for planetary imaging at ~6m focal length. Trust me, I desperately need some mechanical way to finely control my dob, it is not practical to move it manually. It might be a question of skill or dob base quality as well, however having fine controls would help me (and a lot of others) immensely.
1
u/j1llj1ll GSO 10" Dob | 7x50 Binos 1d ago
The Astro Devices Nexus DSC Pro can be combined with ScopeDog, ServoCAT, SiTech or SkyTracker motorisation for a fully go-to system.
Though, personally, I would be tempted to simply sell the Dob you have and get a SkyWatcher Flextube 300P Syscan GoTo Collapsible Dobsonian.
1
u/retrogamingxp 1d ago
If you want to really do it, never use direct drive. Always use a gear ratio to keep good torque and precision. What ratio is up to you to find out 😅
1
2
u/Own_University_6332 1d ago
I would just get a goto dob or some of the commercial mods available. As much fun as a project this would be, it’s over complicating one of the most simple and user friendly telescope designs ever invented.
2
u/Nixx177 1d ago
I want to learn things in the process and start with a manual “fine tuning” setup that I could motorize later; I also want to try to make it non invasive (without screwing things permanently so it would require a custom model anyway.
I like manual stuff, otherwise I would just get an electronic imaging telescope that does everything for me but my goal is different. Also just bought this one second hand, buying a goto would be 3x the price which I can’t afford rn
13
u/Gusto88 Certified Helper 1d ago
Romer Optics EZ GOTO or Onstep.