Thanks! Sure, if you scale everything up it should work for any size. I would also increase the wall thickness and use at least 15mm belt width, to be able to handle the bigger mass. How large is your 3D printer? It might make sense to use a circular wood, metal etc. for both axis and just 3D print the outer belt profiles and mounts.

@@jaketechblog , thanks again. Do you think doubling up the motors might better? I feel single motors might struggle to move a 12” beast. Then again, I am unfamiliar with stepper motors. My printed volume is about 25x25x25cm, roughly. I will have to print the gearings in many parts, I think. Can you power both motors at the same time so that the scope moves diagonally, not up then across, for example? Thank you

@@SeanDuguid Dual motors in a single belt loop? Not sure if that would work well with the belt tension etc. It would be probably better make a whole double pulley/belt system per axis then, but I am not expert with mechanical stuff to be honest. One thing that I know about steppers it that they have a high holding torque, but it declines with higher RPMs, you can find many torque diagrams on the internet. So in any case it should would work with slow accelerations. Also I think doing the calculations makes sense here, for example I am using Nema 17 with about 42 N*cm holding torque at the rated current and the tubus weighs about 5 kg. Length is 75 cm, so r = 37,5 cm. The altitude axis has a gear ratio of 21.5, so the torque is 42 * 21.5 = 903 N*cm. Now assuming the weight is equally distributed the average radius is r/2 = ~19 cm. 903 N*cm / 19 cm = 47.5 N. The results in a theoretical max. acceleration of about 9 m/s2, which is quite a lot. Of course I did not take friction into account, in practice it will be a always lower. I guess you should be fine with a Nema 34, they provide from 650 N*cm up to 1200 N*cm and you probably archive also a higher gear ratio, but put in you own actual numbers. Yes, I can run both at the same time, have already tried that, it is just a software change. I will post a software update soon. After that the next step is to mount the electronics and make it battery powered, when it is finished I will post another video.

@@jaketechblog , thank you for your continued reply and assistance, and my apologies for the belated response. I am going with the Nema 34, 8.2 Nm motors since my rough back of the envelope numbers are in that range. Next step will be setting up the software side of things, of which I have a few questions. Why did you choose to use an Arduino? Did you find it better than a Raspberry Pi? You mentioned that you post a software update and hardware upgrade. Any idea when this might be? I look forward to seeing more of your work. Thank you once again, Sean

@@SeanDuguid No problem. Did you already work on the mechanical stuff? And do you want to publish it as well? Would be surely cool to see with the large telescope. I can also put up a link or directly showcase it on my blog/YT if you want. Many use a RPi and I don't think that it is bad. Just overkill in my case, because the plan is to always take a laptop with it, so I don't need another full Linux on an RPi, the Arduino should only handle the calibration and control the motors. The laptop then has the software with object database and provides a proper screen and keyboard. I think about wireless connection, so I am probably going with an ESP32 which has builtin Wifi and Bluetooth. Other projects have a more standalone approach, with a screen and control panel firmly connected to the base, for this a RPi would definitely fit better. It is the next project on my list, so I think I will look at least at the software in the next 1-2 weeks. Yeah, I know that I interrupt projects sometimes for months or even years, I am trying to get better with this.