Gina

Gradually advancing the design of the lens cover motor casing to fit it as close to the lens as possible to reduce the length of the arm. These are just test prints to check fit, hence the low "wall" round the edge - just high enough to be sure the motor will fit in. The bottom end will need a curve to fit onto the main casing where it will be glued on. I shall make a hole in the casing for the motor wires.

Forgot to allow for the filament thickness and the motor wouldn't quite go in so I've changed the design and printing it again.

That seems to be the main casing sorted out and now looking into the lens cover motor housing. This is a first attempt to see how it fits. This has the stepper motor driving the cover arm directly. Previous design had a pair of gears giving a slight step down ratio.

A couple of photos of the casing glued to the base/bracket. I'll tidy it up and fill hollows and also improve the inside fillet. ASA dissolved in acetone.

I think I can simply glue the main casing onto the base that also forms part of the bracket that holds the weather station wind instruments. I have elongated the hole in the mast tube where the power cable came through and I reckon I can again run the cable inside.

Printed and fits perfectly

Two beautiful vinyl collections of songs by Nana Mouskouri Plus a USB cable and some capacitors and FETs

Yes, beautiful A really professional job

Motor bracket and casing support.

Still not sure. And the diagram above is wrong - the focus motor comes almost out to the casing. The focus motor support could be extended out to the casing and two more "legs" could fully support the casing. Also, having the heatsink clear would allow heat to rise up to the lens and help with dew heating and the casing would be supported further up which is more effective. This method would use less filament too.

I'm now looking into the mast mounting and how the ASC works are fitted into the casing, the run of the power cable etc. This is a new way of mounting the ASC casing and presents new problems, particularly with the power cable. Previously I have run the cable inside the mast tube but this is much more difficult now. It would also mean drilling a hole in the lower mast tube. I know many people just tie the cable to the outside of the mast and maybe I shall have to do the same, at least for the time being. This would certainly cure one headache The ASC casing needs attaching to the "works" to keep everything aligned properly. One way is shown in the cross-sectional diagram below which I think may be easier than a ring and spokes from the aluminium heatsink block or camera which was my first thought.

Completed casing side view. The main casing still has the brim from printing. The lens cover motor in its casing should easily fit above the lens cone while still being below the lens.

Here's a photo from above showing the ASC in casing showing how the RPi & Hat fit in. If it it turns out that I need a separate RPi for the weather station, there is plenty of room for it

Main casing printing finished and now just waiting for it to cool. Making healthy creaking noises as parts of it come off the bed as it cools...

Finished wiring up the HAT for the new component positions. Main casing still printing... Should be ready for testing the remote focussing soon Maybe tomorrow. Be quite some time before I'll be able to test on the stars - cloud forecast for the foreseeable future!!

Tidied up the lens cone and now printing the main casing - just a cylinder 138mm OD and 2mm thick by 120mm high. Printing time 2h 10m.

A photo showing the lens cone with extensions. Cone rotates with lens for focussing. Print not tidied up yet.

Due to the height of the stepper motor drivers on the RPi HAT the diameter of the casing is going to have to be about 140mm diameter if it's a cylinder. If it wasn't for the rotating lens cone it could be oval, as I've done in the past. It might be possible to arrange the RPi etc. below the bottom of the lens cone but I doubt it would be worth the effort. Also, if I go for 140mm I can use the lens cone I've already printed if I add a bit extra on the top and maybe a bit extra on the bottom to provide a better overlap to keep wind driven rain out. Furthermore, the RPi can be moved up into the cone and save 20mm on the height. I think with this system I can get the motor drive for the lens cover above the lens cone and reduce the length of the arm but this remains to be proved.

Not sure I like that - cover arm seems too long. Trouble is, although this is 3D CAD software, the display is always 2D and that makes things a bit difficult. Also, things like the domed cover are quite difficult to construct in 3D. Of course, I have to do it for printing but seems a chore just for a diagram. Measuring the RPi and USB plug and from where it fits with respect to the camera, the main casing will be 140mm high and this is the height shown in the diagram so it wouldn't be out of place. The other point is how strong the gearbox is in the stepper motor and the windage on the cover.

Here is an alternative with the motor etc. lower down.

This diagram shows how a little stepper motor might be direct coupled to the arm which operates the lens cover. It would be covered by a small enclosure, of course. This arrangement might be simpler than drive rods, belts or cord.

I'm straining my brain trying to think up a way to drive the lens cover while keeping the stepper motor dry. The motor will want to be inside the main casing or possibly in a little pod. Drive could be gears, axle with bevel gears, timing belt and pulleys or even fishing line cord and drums (like I use for my 3D printers). Whatever I use must all be below the edge of the lens or it would obstruct the view. In typing this I have activated my brain a bit An idea has occurred to me - I wonder if I could use direct drive with little casing containing the stepper motor on a sort of "stalk"

Yet another re-design of the ASC is looking promising. I think I can avoid the need for lens alignment adjustment and reduce both the complication and size

Since the lens rotates, the yellow part in the diagram above will rotate with in and hence the casing will have to be circular in section too but depending on the electronics the casing might be 120mm or 125mm rather than 145mm so a bit smaller.

Since the lens now rotates (for focussing) I can't fasten a fixed casing to it. Instead the lens can have a separate conical shaped part attached with overlaps the main casing. The lens cover would then cover this. I have yet to decide how the cover will be controlled.