Gina's Mini Dome Observatory for Widefield Imaging Rig

[Gina]

Looking at connecting the dome with the casing for the mount.  This is not "it" yet - I want the horizontal part sloping downwards.  Work-in-progress...

[Gina]

I could do it like this cross-section to give a slope but I don't like flat printed parts at all if I can avoid them so I will apply more thought to this.

Edited August 20, 2019 by Gina

[Gina]

The dome could be arranged like this, with appropriate attachment to the mount casing.  The black line represents the mount RA axis.  Less than half the dome shown would open.

[Gina]

This might be one way of fitting the dome to the mount casing though I have yet to look at the practicality of splitting the dome into sections for printing.

[Dr_Ju_ju]

I realize there must be some level of complexity, but.....

[Gina]

Using the clamshell form makes it simpler to implement than a shutter type and this takes advantage of the ability of 3D printing to produce almost any shape and curves are better than flat planes.  Plus I like the spherical shape and playing with CAD software is fun in itself.  This is a bit of light relief from the main project list.

A more conventional shape of dome might be better, attached to the ground rather than the pier.  I already have four fencing spikes in the ground around the pier that I was originally going to use for a mini observatory.  OTOH the dome shape has to allow for the appropriate part to open to give the required view of the sky.  This leads to the design in the screenshot below.

The opening part of the dome could be driven by timing belt and pulleys.  With the pulleys being aluminium or plastic and rubber belt, they shouldn't hurt being outside.  The motor would be inside the casing.

[Gina]

Dome and part of the mount cover.

[Gina]

The dome and part of mount casing.

[Gina]

The fixed part of the dome only.

It may be possible to print it like this but could be made in two parts with an interior flange joint :-

[Gina]

I think I have a way to print the fixed part of the dome plus a bit of the mount casing which can be overlapped with the rest of the mount casing and secured.

[Gina]

Printing the above to a small scale - 30% of the final expected size.  Just past half way and so far so good except for near the start where I suspect the scaling down has caused an issue with the filament width (less than one).

[Gina]

Print finished and proved that the model was viable in the sense that the overhangs could be handled without problem.  The main problem with this print is that the thickness went below one layer width resulting in tiny gaps between layers.  I think I'll do a 50% scale print - the biggest I can get on the Concorde printer.  I can then go on to produce more 50% scale parts for testing.  I know I can model everything as an assembly to test that parts go together but I don't think you can beat a scale model for showing up problems.

[Gina]

This design isn't right yet.  I think I need to do more CAD modelling...

[Dr_Ju_ju]

In your slicer, make sure the thin wall thickness is being detected & 'fattened' up....  I don't know if you are using Slic3r but Prusa's version is loads better & not just for the Prusa printers....(https://www.prusa3d.com/prusaslicer/)

[Gina]

Yes, I am using Slic3r.  I've heard the Prusa version is a lot better but not tried it.  I've downloaded it and seems it needs compiling.  No problem - done that a lot with INDI drivers etc.

[tekkydave]

19 minutes ago, Gina said:

Yes, I am using Slic3r.  I've heard the Prusa version is a lot better but not tried it.  I've downloaded it and seems it needs compiling.  No problem - done that a lot with INDI drivers etc.

You may have downloaded the sources by mistake. There is a compiled application on the prusa slic3r website Here

[Gina]

Can't seem to find the compiled Linux version of PrusaSlic3r, only the firmware and a link to GitHub where they have Alpha releases.

[tekkydave]

Strange - they seem to have removed the old Slic3r PE downloads. Looks like its now up to your Linux distro's maintainer to provide a packaged app.

Or , as you say compile it yourself. Shouldn't be a problem if you have all the dev tools installed.

 

[tekkydave]

Just had a look at the github site. If you download the file with the .AppImage extension it should run by double-clicking directly on the file.

[Gina]

OK downloaded the.Appimage and tried to run it - got this

[tekkydave]

Is it set executable in its permissions?

[Gina]

I'll check.

[Gina]

It wasn't but it is now and it works - thank you.

[tekkydave]

In case anyone is unaware of AppImage and how it works see this explanation.

[Gina]

PrusaSlicer running and set up in Expert mode - I like it.  Now to try a print from it...