Gina

I have a roll of it in the kitchen cupboard.

This is the sort of arrangement I have in mind with a hinge between two aluminium plates. The dome part can be ignored - the new dome will be bigger. Sorting out the RA drive looks like being "fun"!!

That aluminium plate the pillow blocks are attached to is not thick enough - I can bend it. I do have a thicker plate I can use.

Here's a photo of a redundant aluminium plate with the pillow blocks mounted on it.

I've been thinking about the main construction again and how massive (or not) to make it. I already have a massive part construction using heavy duty pillow blocks and aluminium plates. This seems like over-engineering with a vengeance for a payload of well under a kilogram but that's better than under-engineering and it's there. Those pillow blocks are over 6" wide.

Adhesion to the print bed is totally necessary otherwise the print would move about or fall over if tall. With a warm bed and print the print will usually stick to a glass plate or various things applied to the glass. As the bed and print cools the adhesion should break and the print be released. HTH

The print was adequate for purpose if not very pretty. Here are some photos of the rain detector fastened in place. I have yet to secure the cable.

I don't think so. How do you mean to use backing paper?

I managed to get a thin, small screwdriver under one corner of the print and lever it off. With just glass prints came loose when cool. Also, the surface of the print against the PEI sheet is very rough unlike the mirror finish obtained with glass. I'll try it a bit longer but so far I'm not impressed.

Phew!! Well I managed to get the PEI sheet on the glass reasonably flat - a few bubbles and ridges but not bad overall. I'm not sure the PEI sheet was a good idea - the print, though cold is stuck to the sheet!!

PEI sheet and glass plate are on their way here so I'll be able to fix my Concorde printer this afternoon ready to make a bracket for the rain sensor. I've decided where to put it and that's on the drop-down window, well away from the main roof in a clear, open space.

I'm thinking of a mixture of metal and plastic in the construction. The most important aspect of a mount to be used for a widefield rig without guiding is polar alignment. With good PA guiding is not needed and the motion is in RA only - Dec is only used to frame the image. This results in a much simpler system. The important thing is that PA is maintained and that is where the metal parts come in, to avoid the creep in plastic. The other critical requirement is that the mount move in RA at the correct rate but since this is relative after the image is framed, it isn't affected by creep. One requirement this mount has in being entirely remote controlled is that the PA also has to be remote controlled. Although this should be a one-off process, to use manual PA would mean having a computer display at the pier to display the images. Overall, I think remote PA will be the best option. It just means two more remote controlled stepper motors.

This project may be resurrected in the not too distant future. Not yet though as I have other priorities. Nothing to stop me thinking, planning and tossing ideas around in my brain and here for discussion. It goes with my micro-dome observatory project, also in sight of resurrection sometime in the next year or two. I think I've pretty much decided to go for a single widefield imaging rig to reduce the size and complexity for my first attempt at making a mount and getting it working.

Work on the ROR automation is proceeding apace now though still lots to do. But I'm also thinking ahead a bit to future astro projects. In particular the micro dome and DIY fork mount for widefield imaging which would free up the main full sized observatory for narrower field use with telescopes rather than vintage SLR lenses. I have two ASI1600MM-Cool cameras which would lend themselves to a dual rig or two independent rigs. Unfortunately I only have one set of Astrodon 3nm NB filters which is a little limiting. I have a micro-dome half built which is a standard design with shutter but another of my projects is the Giant 3D printer with which a larger dome would be feasible. Another thought inspired by another thread is a clamshell type dome - something I have thought of in the past but not made much progress on. My greater experience in designing and making 3D printers and printing techniques leads me to believe I could do a lot better now than I did with my other little dome. The advantage of a clamshell design is that it doesn't need rotating and also I think a clamshell may be easier to automate than a standard shutter. The advantage of a standard dome is shielding from wind and stray light, of course.

Hooray!

Some improvements made to the chain drive including adding a tensioning spring and adjustment. The eastern attachment bracket remains the same but the western end block has been replaced by an eye bolt through the end frame of the roof and a heavy duty spring. Also the smaller chain pulley has been replaced by a bigger and stronger 3D printed version employing two ball bearings and an 8mm coach screw into the motor baseboard. This was to cure the chain climbing up onto the edge of the pulley and to improve the chain movement generally. Two screenshots of the new small pulley design. New pulley installed. Spring and eye bolt, which provides for tensioning the chain.

WOW just WOW!! Incredible, amazing, wonderful! Well done everyone!

Raining now so just as well I've finished outside. Did have a brief shower this afternoon too but nothing much. But the rain has reminded me that I haven't mounted the rain detector in/on the observatory yet. There always seems to be something else to do.

I think that's the mechanics done now comes the electrics and electronics and then the firmware coding... Yep!! Still lots to do!

That operates the clutch. Disconnects the motor drive (worm gear) from the drive sprocket so that the roof may be opened or closed without running the motor or in event of motor failure. It's self-latching so one pull disengages and stays disengaged then second pull releases it and it engages.

Herewith some photos. Firstly the new small chain pulley then the spring attachment to the ROR with an eye bolt.

Lovely looking pair of domes!! Great job!

Been out to observatory and fitted new small chain pulley. Also altered fixing to roof where spring attaches to an eye bolt so that I can adjust the chain tension. Photos to follow. Having a cuppa break ATM.

Blimey!!! You're right the price has gone up £6 during the day!! Ordered anyway.