Gina

Mmm.... Tricky.

Regarding weatherproofing where the roll-off-roof and warm room roofs meat when ROR closed, these photos from my build may be useful.

Ordered this :- 12V 1.5 Kg Force Energy Saving DC Tractive Solenoid Electromagnet

I guess I could cover the whole dome and take a dark.

This ASI 120MC-S camera seems to be more sensitive than the ASI 185MC though I guess it's difficult to tell with the moon in the image. There another difference too - when the 185 was imaging the sensor temperature increased whereas with this one it doesn't. The 185 had a separate image sensor PCB whereas this has the sensor mounted directly on the main PCB. I guess I should stop imaging and get on with the construction...

Camera temperature has now dropped to -0.2°C. Part of image - 60s exposure, gain of 50. The clouds have gone.

Camera temperature has now dropped to 0.5°C. Part of image - 60s exposure, gain of 50. Here comes the cloud...

Camera temperature has now dropped below 1°C. Part of image - 30s exposure, gain of 50.

Camera temperature has now dropped to just over 1°C. Part of image - 30s exposure, gain of 50.

Camera temperature has dropped to just over 2°C. Part of image - 10s exposure, gain of 50.

Darks are a problem as the lens doesn't have a shutter or aperture control.

Moved ASC outside onto the window sill. It's now slowly cooling down towards outdoor ambient. I realised that I'm not ready for cooling as the camera needs clamping onto the Peltier TEC.

Here is part of a screenshot of the KStars FITS Viewer with the camera looking out of the living room window to the south. No cooling - I'm going to set that up next. Camera temperature is 13.2°C so camera image is showing plenty of noise and hot pixels.

There is already a 5mm thick adapter to convert C to CS mount so no problem there.

I've checked the motor opening and closing arrangement and it looks like shall not have to move the large pulley ? I have also checked the NW corner and I can indeed use the same system as for the SW corner, assuming I can get the parts. I haven't decided yet whether the latch that holds the roof will be on the south side or in the middle. Here's a photo showing the middle roof beam and the dividing wall with the roof closed. The solenoid latch could go on the dividing wall and the latch plate on the roof beam.

Decided the NEMA14 stepper motor I used before was overkill as well as taking up a lot of space so I'm replacing it with the ubiquitous 28BYJ-48 mini stepper motor modified for bipolar operation. This is much easier to mount and in this application, one screw is sufficient as it sits nicely into the curve of the camera casing. It will need a new pinion plus a spur gear on the lens shaft. This provides focussing using the thread of the lens mount (the lens has no focus mechanism).

That's a thought ?

I wondering whether to use some of the new silica gel crystals from one of the bags and put those in the space inside the camera enclosure rather than using a tiny silica gel bag (that I don't really know the state of). The top part of the casing could have a hole through to the inside which would be sealed with a plug or cork. This would mean not only being sure of fresh silica gel but fill all the spare space.

There's a farm supplies shop in town and they have a selection of hardware such as gate hangings, latches, bolts etc. and I'm thinking of going in next week and seeing what they've got. The eye-bolt and gate latch pin I used before came from there. Also, the weather looks like it might be suitable for going out to the observatory and checking a few things.

I mentioned the problem with the roof being blown very slightly open against the locking pins and causing friction so that the solenoid was unable to pull them out, in a post above, followed by a lever idea to reduce the drag on the solenoid but your idea is another way to do it. There will be a sensor to check that the roof is closed to stop the closing action anyway so the software could check that the roof was fully closed before trying to open it and if not then close it first.

I think I've found something to lock the east end of the roof. GATE HOOK AND & BAND HINGES - HEAVY DUTY STABLE STRAP GARAGE SHED BARN DOOR RND Or maybe something heavier. The idea would be to fasten the gate hook to the roof framework and the hanger to an upright on the main observatory framework.

If I have pin and ring-bolt locking system (as below) or similar on the four corners of the roof, that engage when the roof is closed, I will only be necessary to lock the roof closed so that pin and eye stay engaged. These photos show the pin and ring-bolt locking system on the SW corner of the roof. The pin is in the west end beam of the roof and the ring-bolt in the partition framework between scope room and warm room. The 3rd photo shows the end of the pin bolt on the outside of the ROR, which is in the open position for this view. These are farm gate fittings and very strong. I can do exactly the same on the NW corner which is just a mirror image. The east end corners will need looking at. The SE corner did have a peg which went into a hole in the frame but the hole has broken out and will no longer work.

Here is a simple lever design that reduces the force on the solenoid.

Safety and reliability are paramount.

My partner Tim had the vari-focal lenses on the NHS. Afterwards he could see well at a distance and also to read close up. He was delighted. Apparently, they are soft lenses that change shape like the real thing when you are young. This was at a specialist eye clinic in a local hospital with a renowned reputation.