[encypruon]

Great project and excellent presentation!

I've been trying to build something similar for tracking birds / panoramas / photogrammetry while avoiding using non-printed parts as much as possible but haven't been very successful so far. Because of that I'm particularly interested in the printed gears you are using. Maybe you could help me with some of my questions and concerns.

It looks like the whole thing is designed to be stiff, which means that the gears are pretty much at a fixed distance from each other. Doesn't that lead to backlash / play if the gears are a little bit too far apart or vibrations if there is too much pressure pushing them against each other? I've been worried about this and experimented with mounting the stepper motors on flexing parts to keep the pressure consistent and allow for more imprecision in the prints but I never really tried whether I can get away without that, so I'd be interested about how well this is working for you.

Pictures on the flexible motor mount idea: https://imgur.com/a/mM1Uql9

I would also like to know if there are any signs of wear after using the thing for a few days and what materials were used. I couldn't find anything on the type of filament on your website (did I overlook something?). I've only ever printed PLA so far and found that the gears would turn more smoothly after being used for a while. I imagine that the effect of wear might be different on the design without flexing parts.

Is it correct that the upper part is resting / sliding on "base-2"? Or is the bearing doing most of the work? Does it wobble at all? That was another one of the problems I had.

[dvoros]

Hey there, thank you for the feedback!

Yes, this is completely stiff, no flexible parts. I've experimented with a few gears and different distances between them. I've found that this herringbone gear works very well. I don't experience any visible backlash, but the gearing ratio also helps to suppress that.

I've printed everything from Hobbyking Premium PLA. Just as you've described, the rotation gets smoother after some wear. But even after 30-40 hours of use they still don't seem to become loose at all.

Securing everything on the bearing, there's no visible wobbling. I really recommend using a bearing if possible, it makes things so much easier. (:

Good luck with your project! (;

[encypruon]

Thanks a lot for the answers. And for everything else, too!

[dekhn]

if you really care about backlash, just measure it and then add a correction in your motor controller.

Another way to do this is to always move back to endstop zero, and only move forward. THis is very limiting.

The biggest problem I had was all my PLA prints melted in the direct sun!

[encypruon]

> if you really care about backlash

At 1200 mm equivalent a picture is only about 1.15° high, so accuracy is important :)

> just measure it and then add a correction in your motor controller.

I think your first idea doesn't really work for tilting because there is little friction and the camera isn't going to be perfectly balanced (the center of gravity also changes with the focal length and even the focus). When gravity pulls the camera towards one direction backlash is less of a problem, but when it's near the tipping point it becomes really shaky and sensitive to disturbances. Past the tipping point it is biased towards the other direction.

Preloading might be an easy fix but at the cost of acceleration.

> Another way to do this is to always move back to endstop zero, and only move forward. THis is very limiting.

At least for panning in panoramas this isn't a bad solution at all. I think both your ideas are good for panning with planned paths.

> The biggest problem I had was all my PLA prints melted in the direct sun!

Was it white PLA? So far I've only had stuff bend out of shape in the car.

[dekhn]

I've built a similar device to this (originally for a solar tracker that keeps the sun at high magnification in the middle of the frame, but it turns out to be ideal for panos as well).

It's a DSLR with crop sensor, 300mm lens, stepper+gear for azimuth and stepper+belt for altitude (with gearing to get more torque for both). I used this system with Hugin to assemble 180 degree x 180 degree, 5 degree azimuth and altitude steps (so, about 5X your resolution, I don't have the same zoom as you). Results are great- I can give this straight to hugin, update a PTO file with my known angles, and it assembles without any futher optimization. I do pan with a planned path.

If the belts are real tight, backlash is neglible (seems to be a lot smaller than any gear I could print). If you're having that much backlash on tilt (that it's shaky and sensitive) I think you might need to re-engineer the frame to be more stiff (which will cause the shakes to dissipate faster) or tune your motors (tuning velocity and acceleration). You might also be able to use a spring to keep the gear in place. I tried to get a 3D-printed worm gear working, but never made it compact enough to be practical for the altitude.

I had white PLA, in direct sunlight/90F ambient for hours, and it warped. I only noticed because I was inside watching the incoming images and the altitude staged started to "melt" causing massive positional losses.

[encypruon]

Good results without optimization at 300 mm sounds pretty impressive. Maybe belts are the way to go. Thanks for taking the time to elaborate!