Gina

For the Z carriage (print bed), instead of having a wheel running on each of the 4 uprights, I'm going to have 2 wheels each running on the front 2 uprights and instead of having the bed supported on each of the 4 corners I plan to use 3 supports, 2 at the front and one at the back in the middle.

Current arrangement.

Change of plan - no complete rebuild, I'm going to try stiffening the frame and improving the Z carriage/bed arrangement plus a few minor tweaks and see how that works.

Apart from my own DSO images I may also use some from the web such as Hubble ones though of course, I shall make it clear that these aren't mine.  I'm also thinking of describing various types of amateur telescopes and using camera lenses for widefield.  Tripods and piers should also get a mention I guess.  Then there's mounts, observatories, cameras, filters, etc.  I guess a none too detailled explanation of image processing should also be included. 

I have to bear in mind that this is a general audience probably with little knowledge of physics or maths so all explanations have to be very basic. 

Latest plans with some changes (may call the upgraded Mk.2) :- 

1. I very rarely use ABS these days as I feel it has been superseded by better, more user and environmentally friendly filaments.
2. Probably change bed heater to 240v AC.
3. Parts cooling system almost done, though this might change with changes to X carriage.
4. Change from inductive Z probe to Precision Piezo and nozzle contact probing.
5. I shall be using thick (18mm) plywood for the framework/box for rigidity.
6. May change from cord for XY drives to timing belts and pulleys though this would result in a larger overall size.

I am now thinking of replacing the inductive Z probe with the Precision Piezo sensor that works by probing with the nozzle.  This will give more accurate and repeatable results, avoid all the setting up required for inductive probes and avoid Z probe setting up when changing hotends (Concorde has interchangeable hotends).

Correct - and it was a bit too much for PLA - fine with PETG though.  I think PETG is my favourite filament.

Designed and now printing focus gears.

A couple of photos, camera casing and RPi roughly where it will go and printing the top outer casing.  Printing in cheap PLA, low resolution, for prototype.

Yes.  No problem as the error is tiny and easily compensated by the firmware.  In other printers I have had a slope of 5mm across 200mm and the firmware still coped fine.

Another.

This is a bit better.

Had a thought, rather than redesign base and camera casing top I reckon I could simply mirror image everything in the slicer and print what I've got.  Present prints are only test prototypes anyway - I shall print more accurately when I have the final design and everything fits together properly.

Hmm... well.  I've just tried the new right angled plug USB lead and found the B plug is the opposite hand from the one I designed for!  Back to the drawing board - CAD software.  At least the A plug is right for the RPi.

Yes, you're right, LH bottom should be green.  Z homing should set the start point unless I'm missing something.

No testing tonight even if it is clear.  All design work which I think is almost done.

Matching bottom part of the casing.  This is screwed to the passive cooler with M3 screws and to the top part with M5 screws from underneath.

Model of the top part of the outer casing.

If I solder the RPi power input wires directly to the board I can save 10mm height allowing for a slope on the top otherwise the top would be flat which I don't like.  I'm changing the arrangement and having the top go right down to the level of the inside of the bottom part.  That will make clamping top to bottom easier and put the seal lower down so that if there was a leak it would be below the camera.  Not that I intend there to be any possibility of a leak!

oops - forgot to allow for the RPi.  OK new design needed... No problem.

The basic top part of the casing, connecting dome to bottom part.  The dome can be attached with a ring on top of its lip screwed to the top ring of the casing, with a seal between.

This solves the problem of holding the camera casing together but not attaching the top of the outer casing.  The top needs clamping and sealing arrangements for the dome and for attaching to the bottom part.

New designs for basing bottom and camera casing top, the latter underside view.

Decided.  Going to put RPi with its HAT and the buck converter in the ASC casing.  Just need to increase the size a bit.

Good thought ?   Though not the warm room as that gets covered by the ROR but I am planning to mount it on the north side of the ROR.  The dome has to be above the roof to get a view of the sky to the south.  I could shade a lot of the casing though.  Last time it was mounted on the south side in the full sun.  Maybe it won't get too hot.

If it weren't for the enclosure getting hot in the daytime in summer I could go back to having the Raspberry Pi and the other electronics inside the ASC casing rather than in a separate box in the observatory.  Two advantages - it would save having to seal lots of wires, with just power connections remaining and also output heat to warm the dome and with the inside being dried it's only the outside of the dome that can suffer from dew.