Jump to content

sgl_imaging_challenge_2021_2.thumb.jpg.72789c04780d7659f5b63ea05534a956.jpg

wobblewing

Members
  • Content Count

    78
  • Joined

  • Last visited

Community Reputation

24 Excellent

About wobblewing

  • Rank
    Nebula

Profile Information

  • Location
    Cambridgeshire, UK

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

  1. I created a longer timelapse and it appears that I can see: - PA alignment error (will do better next time). Noted the other more accurate technique. - a small amount of non-linearity as it approaches the centre of the sweep and the 'turnbucke' (ball joint thingy) goes horizontal - you get a tiny amount of speed drop requiring less than a millisecond of 'per step' adjustment. I'll approximate it into a number of linear portions of the sweep. - more significant I think is that the step signal of the micro:bit appears to jitter due to using micro python (interpreted code), it's
  2. I'm running another timelapse video over the whole sweep, so it might help characterise the non-linearity (maybe)
  3. A single 8 second sub, ISO 500. Looks kind of promising for an afocal effort. Will DSS this lot. My talent probably runs out here
  4. Well, clear night tonight finally - albeit with a full moon! So, testing the tracking out.. here's a hyperlapse video.. bear in mind this is ~22mins squash into 22seconds! I can juuuuust notice the non-linearity, which equates to about one third to a half millisecond timing on a step.. Will fiddle with the code, but it's not really necessary as it exceeds the exposure length I can do with my phone up against the lens. Not quite sure what the up and down is all about I think my PA needs work... But the hyperlapse really amplifies it... in real time it doesn't seem like it move
  5. I just realised I put this in the wrong thread - I've copied this post over to there, but cannot seem to delete it from here! Sorry. Well, clear night tonight finally - albeit with a full moon! So, testing the tracking out.. here's a hyperlapse video.. bear in mind this is ~22mins squash into 22seconds! I can juuuuust notice the non-linearity, which equates to about one third to a half millisecond timing on a step.. Will fiddle with the code, but it's not really necessary as it exceeds the exposure length I can do with my phone up against the lens. Not quite sue wha
  6. I would be quite up for making my own 12in dob. I'd build it onto a scaled up version of the platform above.. but the mirrors seem to be as expensive as buying a complete telescope, so not sure if it's worth it!
  7. One of the difficulties i have is that i cannot easily see polaris from my observation spot. My garden is south facing but just around the other side of my house is a street lamp which causes some interference. So I sit the 'scope out the way off the street lamp by hiding behind the house, but then i cannot see polaris! I waited for solar noon, projected the sun's position onto the ground with a broomstick and then put a small mark on my patio to line the platform against!
  8. I'm struggling to get spot on Polaris alignment throughout the whole travel, but this is because of me and I'm getting used to it! I'm thinking about making a little gadget that clips onto the back to help with alignment (or maybe something that clamps the OTA into a fixed spot for alignment with the red dot finder). That said, rough alignment seems to work perfectly for visual.
  9. It is definitely moving in Z and Y, whilst being pushed along X (the ball joint)... but I think it's such a small amount that it's insignificant. We will see I might have a go at some geometry calculations to see how much it is.
  10. A few CAD images from Fusion 360... Ok, so I used white PLA instead of black Latitude 52deg. Adjustable levelling feet give probably +/-4deg ish. Total movement ~125mm giving 82minutes of travel.
  11. 1) actually I tried 3DP rollers to start with, but found them a bit lumpy due to the FDM layering. I switched them to skateboard bearings (had a set in my spares box!) and it made it run much smoother... I also put an open bearing in the South pivot point as I found 3DP friction bearing a bit 'sticky', although the torque of the drive mostly overcame it... By using bearings the movement is very smooth indeed. I printed the sectors to get the FDM layering along the axis of movement and then sanded it to get a very smooth surface to roll on... It's super slick and smooth. I had more of an is
  12. Right now I've only got about 90mins use playing around with it.. Since my dob is only little with a FL of 750mm, I tried a 3.2mm BST EP looking at a star (thus x234 - approaching the practical limit of the scope) and it was holding in the centre of view really well as far as I could tell... the problem is it was quite windy and getting knocked around a bit - so more time will tell! Also, only Mars is available at the moment and it's getting very small... so not much more useful than a star in terms of seeing how well it tracks. In theory I'm sure there is some non=linearity to deal
  13. Interesting thought... I only intended to make it as a one-off for my own use! It was very cheap on materials, but I spent quite a lot of time on it... I need to get a bit of experience on it first... I'm a newbie in terms of astronomy, so I don't really know what to gauge it against.. Also, I'm only doing afocal photography using my phone with a 3D printed 'phone to eyepiece' adapter, so I'm not sure if my photography setup is capable enough to really characterise how good the platform is... My engineering nouse suggests it's reasonable, but I may find foibles as I gain experience with
  14. To close this thread: I finally finished it! I ended up having to pay £2.30 for a stepper motor driver PCB (not Free ). Other than that, it's from the parts bin and made from an old shelf. All 3d printed included the ball joints. Driven by a stepper motor and worm gear pushing/pulling the platform (way more torque than needed, but this can be turned down on the driver PCB)... BBC micro:bit coded in Python... Powered by a 2S or 3S Lipo.... It actually works really well and I've got the accuracy spot on! I had no issue at all with the pot
  15. I had no issue at all with the error induced from pushing the platform following a circle profile by using a linear leadscrew. As you can see the motion is as good as linear through its entire travel, so a fixed speed across it (without varying across its travel according to position) worked out fine. I was going to replace the brass leadscrew 'nuts' with a split nut design so it's fast to reset.. but I found that it only took about 10seconds to spin it back by hand - so I didn't bother. There are no limit stops with microswitches, I basically reset it to the start position a
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.