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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

DIY Flatfield Dustcover with RPi

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Getting closer... There was no way for me to get the cap really good closed without that magnet trick. Because of my sloppy drilling for the caps main hinge there is a lot of slackness. I had to make some kind of "guide clip" for the magnet so that they really meet together at their middle. Those tiny magnets have a lot of force but only if they are really close and centered.

Now the cap closes quite good and the motor has enough force to devide the two magnets :)



After proper rewiring everything I hopefully can do some real tests outside when the scope is back on the mount.
I fear a little bit the flatfield cables might interfere other cables because of its 1kHz@100V power. No idea how this might influence the servo pwm. I also consider a complete rewiring because with the servo and the flatfield I have 5 new cables, one more step down converter and a low/high converter for the flatfields relay (because its active-low). Its getting really messy in my box

I consider to etch a new pcb and put everything possible on it but only if outside test were successful.
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pls excuse my bad english! :)
6 years 8 months ago #17729

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Hi,

when i try to connect the ServoBlaster Cap in the INDI Control Panel I get the following error-message:

[ERROR] ServoBlaster Cap is offline, did not initialize. Service servod not running

Anyone have a idea what can I do?

Best regards
Markus

Sorry for my bad english
6 years 1 month ago #23400

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Is the servod service or the servod binary running on your machine that is connected to the servo?
Is
/dev/servoblaster
existent?
Can you talk to the servo for example via?
echo "0=120" > /dev/servoblaster
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pls excuse my bad english! :)
Last edit: 6 years 1 month ago by pauledd.
6 years 1 month ago #23420

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Post 1

Well,now that I received my first 3d printer from far east I can give a short update of my (never-ending) dustcover project.
I decided to print some of the stability related parts in PLA with my new printer because some parts started to fall of from
that wooden-glued construction under that "harsh" outside conditions...

So I dived a little bit into freecad and things seemed to come out perfectly fitting.






But once everything was connected I noticed that there is something wrong.
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6 years 1 month ago #23460

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Post 2


If I unpark the cap it opens only as much as it does not cover the field of view.
The servo already runs from min to max (90ms/210ms) and of cause I set both open/close to 100% in the calibration tab.



Even with that "on the edge" settings it is not able to fully close. Unfortunately I am not a mechanics genius and I
currently don't really know where to start to optimize...
Maybe I should make that angle longer that holds the flatfield.



There are currently more questions that answers swirling through my mind :blink:

The second issue is that either wrong storage or glueing the angle to the flatfield bent
the whole flatfield acrylic plate a bit outside so that it cannot really close anymore, that's not acceptable
for stationary outside conditions. I think I will either glue a new acrylic plate only on some points or I will
exchange the whole thing by aluminium (0,5 or 1 mm).




If someone has and instant idea what I should change to make that dustcap easily open/close feel free to divulge :lol:

EDIT: I will give freecad's animation simulation a try, maybe I can figure out how to get it work proper.
--= human, without Windows™ =--
pls excuse my bad english! :)
Last edit: 6 years 1 month ago by pauledd.
6 years 1 month ago #23461

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Hi Pauledd,
the servod isn't running. How can I do this? There nothing stand in the tutorial.

Markus
6 years 1 month ago #23505

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Hi. In the tutorial point 5.2 explanes how to install servoblaster
$ cd ~/Projects
$ git clone https://github.com/richardghirst/PiBits.git
$ cd PiBits/ServoBlaster/user/
$ sudo make servod
$ // Follow instructions on screen to add the init script and start servoblaster service (servod)

@Pauledd.

In the youtube video, it looks like you are not using all of the servos travel? perhaps around 80 or 70%?
It looks like you stop the servo travel early at the closed position, so the servo horn does not hit the hinge?

Try using the outer hole for the servo to cap link that you have made. Then reposition the anodized servo horn so it can close the lid with some force, and without extencive binding. It's ok if it slightly binds.

On the picture with the mounting point for the lid, with the circle and question mark.
If you want the lid to have more range. (Now it opens and closes 90 degrees). Then you can make the mount point closer to the pivit point.

If you visualize the circumference of the circle made by the center / pivit point, and the linkage mount point. Then a large circle has the most tourqe, and a smaller circle will have more speed, and in ths case a greater range. (The circumference will be shorter, and the servo will still move the linkage the same length, so the lid will be rotated further around the pivit point).

Hope this makes sense. It's a cool project, and I'm envious of the built in flatlight.
I think next summers upgrades for me will be finnaly mounting the wall mounted flat light :)
Proud owner of Observatory 17b - A remote Linux observatory.
Website: Observatory 17b
Build thread @ SGL: Starting summers observatory project
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6 years 1 month ago #23512

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Thanks Magnus_e for your hints! No, I re-measured the servo horn angle of the min/max positions, its exactly 120°.
If you meant the hole in the linkage...



I used the outer hole before I made the video. The Problem with that was the amount of way I earned with that to the "close" position
was then missing in the open position, it was even less that 90° so that the tubes fov was a bit blocked...Good point, I lose 30° somewhere from the servos 120°.Ok, can you please use the annotations in this image? I dont get it :pinch:
What mount point closer to which pivit point? Do you mean I should decrease circle1?
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6 years 1 month ago #23514
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If you change circle one so it has a smaller radius than circle two, you will get more range, but loose some lifting force.
Proud owner of Observatory 17b - A remote Linux observatory.
Website: Observatory 17b
Build thread @ SGL: Starting summers observatory project
6 years 1 month ago #23515

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Ok, thanks I will try decreasing circle1. However thats strange :huh: where are the 30° gone? I designed circle1 with the exact diameter as circle2, that shouldn't that give the same angle range as the servo does... in theory :lol: I'll investigate further!
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6 years 1 month ago #23518

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I'm not 100% sure, but at the drawing of circle one I see one thing that can possibly be the reason.

The pivot point is not at the point where the angle for the lid arm is. Looks to be half a cm or so offset up to the hole for the link.

Thats the great thing with 3d printing. If first prototype is off, then try again :)
Proud owner of Observatory 17b - A remote Linux observatory.
Website: Observatory 17b
Build thread @ SGL: Starting summers observatory project
6 years 1 month ago #23521

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Success!
I reduced circle 1 radius to be only 80% of the circle 2 radius. I even had to reduce the servos travel distance in the calibration tab.

I had another problem where the cover. It wont open in the most extreme position (most force needed) but I could solve that by moving the rod that holds the close magnet just a little tiny bit away from the dustcap, that reduced the force of the magnets.
The last problem seemed to be solved too. It locked as if the dustcap would not close planar anymore to the foam gasket.
But the cap was not bending as I first thought. The problem was the hole mechanics was to tight/stiff. The axis of the hinge on which the cap is attached needs to have a certain backlash so that the cover can lay/adapt planar on the foams surface.

I will now do some more dry tests before I heft my scope back into the wilderness :)
--= human, without Windows™ =--
pls excuse my bad english! :)
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Last edit: 6 years 3 weeks ago by pauledd.
6 years 3 weeks ago #23845

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