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    Adding 3rd Party INDI Drivers to RPi for Astro Imaging

    This blog describes Installing 3rd Party Drivers into a Raspberry Pi having installed Ubuntu MATE and followed the instructions to run the AstroPi3 script to install INDI and other astro related software.  SSH has been enabled so that now the RPi can be accessed remotely from Terminal.  eg. ssh gina@rpi where gina is my user name and rpi is the computer name as set up during the Ubuntu MATE installation. This set up process is detailed in my blog :- Setting up a Raspberry Pi for Astro

    Gina

    Gina

     

    Setting up a Raspberry Pi for Astro Imaging and Control - Updated Feb 2020 for RPi 3B & RPi 3B+

    INTRODUCTION This is a tutorial explaining how to install an operating system and software into a micro SD card to use in a Raspberry Pi 3B or Raspberry Pi 3B+ for astro imaging and control of the relevant hardware.  The software to capture images, control camera cooling and other things such as the mount etc. is called INDI and provides a set of drivers to control all the hardware. The Raspberry Pi will run in what is called "headless" mode - meaning that no human interfaces ar

    Gina

    Gina

     

    Modifying 28BYJ-48 steppers to run off A4988 driver modules (like NEMA 17)

    I modify my 28BYJ-48 stepper motors to run off the A4988 driver modules, just like the Nema 17.   I use these for remote focus for my astro imaging. These motors come with centre-tapped coils with the centre-taps connected internally.  We need the full coils without the centre-taps and these need to be separate so the internal link needs breaking and center-taps ignored.  This in turn effectively changes a 5v rated motor to one that works fine with 12v. These photos show the coils and

    Gina

    Gina

     

    It’s alive 2!

    Finally bit the bullet and knuckled down to wiring the handpiece- really made a rod for my own back though with the very tight space for the wires...it’s going to be really tricky getting the other half of the housing on there without squashing wires 🤦‍♂️ But it works-almost perfectly-almost that is except the pwm on the LED isn’t pwming 🤔 I swapped from a nano to the new Arduino nano every and I’m guessing the code isn’t totally compatible... 0E01F364-3061-4211-904D-1334A76EFE8A.MOV

    markse68

    markse68

     

    "GinaRep Mini Mk.2" 3D Printer

    A new improved version of my "GinaRep Mini" 3D Printer.  The first version used cord for the drives whereas this one will use the standard timing belt for X and Y and trapezoidal screw drive for Z.  I also expect to use a stout wooden case of 18mm plywood like my Concorde printer, for maximum rigidity.  This is to be a specially accurate 3D printer with option of nozzles as small as 0.2mm.  Print bed will be 200mm x 200mm with around 200mm printing height.  Essentially this is to be a reduced si

    Gina

    Gina

     

    Magnetic coupling

    Initially I planned to make the focus motor quick release and the magnetic coupling made some sense but I ended up going for a simple screw mounted motor so it makes less sense now 🤔 But it’s done now and it works really well- better than I’d expected. It allows for lateral misalignment yet is a nice stiff rotational coupling for the sort of torque required to turn the moonlite knob. A ptfe pad keeps the magnets slightly separated so the two plates can move a little easier against each other. Th

    markse68

    markse68

     

    3D printed housings arrived

    I had to wait an unbearably long time but the 3D printed housings arrived this week and they look great 👍 Surprisingly everything fits- a bit snug but it fits! I’d hoped to get the handset all soldered up today but wasted too much tome shopping so I’ve just been staring at it- psyching myself up to it and trying to plan the best way to wire it- it’s a tight fit and I don’t want to screw it up. The little round pcb is a reverse polarity protection pcb I built for something else that also used li-

    markse68

    markse68

     

    Spider hub

    The spider hub came together tonight- bit of a mare as it’s glued together with high strength retaining compound which gave me about a minute to assemble everything and try to align all the screw holes 😳- needless to say it was a right panic not helped by a friend deciding to strike up conversation at the critical moment. Wish I hadn’t rushed it as it’s not perfectly aligned and not much I can do about it now but it’ll do I think. It’s getting a bit hefty though which is a worry- 200g alrea

    markse68

    markse68

     

    Big improvement- this will work I think

    Disappointed with the function of the design yesterday due to friction issues I’ve modified it- it now has only one spring and 4 screws. The spring keeps the indexing screw in contact with the v-groove in the mirror cell top plate. Adjustment is achieved by slackening all the screws then adjusting the tilt to focuser angle with the indexing screw, and the focuser-axial rotation with the 2 side screws then all 4 can be nipped up to lock it which is better than just relying on the springs I think.

    markse68

    markse68

     

    It kinda works 🤔

    Completed the screw adjuster plate so I could give the swash plate mechanism a try- it does kinda work but I think there’s too much friction in the swash plate and the ball joint- a ready made Igus part. So I’m thinking they might need to be ptfe and polishing the back of the mirror cell top plate will likely help. But getting there I think... 40749B06-F1D5-43DB-9E9C-3ACA97EC0561.MOV

    markse68

    markse68

     

    Starting to come together

    While I’m waiting for the 3D printed parts for the stepper focuser I’be been making a bit of progress on the secondary mount. Here’s the top plate of the mirror cell with the ball joint and the rotation locking grooved insert and a video to show how it’ll work. You’ll have to imagine the mirror tube as that’s next on the todo list 😉 69104768-5797-42C4-ACB7-BF8EE2E23CF9.MOV

    markse68

    markse68

     

    The design

    I like the original secondary mount on my Fullerscope- it cleverly separates the tilt from the rotate of the mirror but it’s a bit crude and too big for my new mirror. The new design is meant to be kinematic and I think it is 🤔 It tilts the mirror on a ball joint and axial rotation is locked by a sliding key way on one of the adjuster screws. There are 2 adjuster screws opposed by strong springs and the second screw and the springs bear down on a nylon swash plate to make the action smooth. The

    markse68

    markse68

     

    The motor mount

    Working on the motor mount this evening- needs a bit more work but the general idea's there. I'm going to use a magnetic coupling and am thinking to make it quick release so I can take it off if I don't want to use it.

    markse68

    markse68

     

    Slight improvement

    24C2AE88-8FBD-47E7-BD34-716FB9018988.MOV Managed to square up the waveform for the step at the expense of halving it’s max frequency🤦‍♂️ But I’ve changed the driver board for the version that actually has half step input so my new max speed is about 3sec/rev which looks ok I think. It’s slmost working how I want it but I need to figure out how to shape the response as it’s too long in the very slow movement then suddenly shoots off into high speed- not sure why as the step times should be lin

    markse68

    markse68

     

    It’s alive!

    It’s very rewarding to see the motor moving 😊 Few issues though- it’s not a very linear response at all. I have a feeling that I need to make the step pulse train symmetrical high/low and just vary the frequency. The Trinamic driver I’m using has this feature called microplier where it interpolates input steps to output 256 micro steps for each input step (or 2 as that’s minimum input resolution I can chose without using serial interface) Nice feature as it makes the motor really smooth but it r

    markse68

    markse68

     

    Oh! those Summer Projects

    Feeling quite 'chipper' today! Many of my little 'summer' projects have been completed and seem to work. First - my bathroom extract system has been installed without me once falling off the ladder or putting my foot through the bathroom ceiling, second - I'm now producing tasty pizza and bread from my DIY wood-fired bread oven without upsetting my neighbours and third I've constructed four  battery powered 'dew zappers' for camera lenses and scope objectives.  The following is proof:

    Hawksmoor

    Hawksmoor

     

    'AP on a Shoestring' Project

    Hi all,   Thanks for dropping into my blog – I have had over 9000 views in total now, which is incredible, so thanks all! As you will know if you have read the previous posts (dating back 4 years or so), I have very slowly been pulling together various bit and pieces of astro gear. Currently I have the following: Skywatcher EQ3-2 mount (white, non-motorised) – second hand for £90 off ABS Skywatcher 150PL OTA – new from RVO for about £180 25mm, 10mm eyepieces and 2 x Barl

    Nigeyboy

    Nigeyboy

     

    Cornwall and Proper Dark Skies

    Hello there!!  Yeah, its been a while since my last blog post. Work and family life have been unbelievably busy these past months – added to that the summer nights being short, things on the astro front have taken a bit of a hiatus. However, the nights are slowly drawing in now, and following our recent holiday to Cornwall I am slowly getting more time to get out under the stars!  A couple of weeks ago, we took a family holiday to Cornwall. We stayed on a working farm, on the edge of B

    Nigeyboy

    Nigeyboy

     

    'Catch a falling star'

    Capturing images of meteors is a bit like fishing. After the event, you are always haunted by the big one that got away! My widest camera lens is a Canon 18-55mm EFS zoom and even though this covers quite a bit of sky there is plenty left in which a bright meteor can suddenly appear. As I had two camera bodies, a Canon 600D and 400D DSLR, I decided to try and use them in tandem to improve my chances of capturing more meteors. Fabricating a ‘meteor rig’, reusing equipment and materials

    Hawksmoor

    Hawksmoor

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