All Sky Camera Revisited

[Gina]

This might be a possible design for the outer casing.

[Gina]

I'm not happy with this design - I'm not sure about the dome clamping/sealing.  In many ways it would be easier with the 4" dome though the 4" dome would give a much bigger area to keep clear of dew.  The dew heater and Peltier TEC connections can use a sealed 4 pin chassis connector but sealing the USB cable is much more difficult.  Needs a lot more thinking...

[AngryDonkey]

I use them on my housing and they are pretty good quality:

 

 

[Gina]

They look good but where can I order them from (UK preferably).  Alternatively I guess I could break into the USB cable and use a standard multi-pin connector.

I guess if I'm thinking of breaking into the USB cable I could get a USB plug for the camera and run multiple single wires through a multi-pin connector.

Edited March 16, 2019 by Gina

[Gina]

The mast the ASC is going on is an aluminium pipe 37mm ID and 45mm OD.  Cables and cooling water tubes will go down inside.  I guess the outer cover wants to be in 2 main parts.  The top part taking the dome and the bottom part attaching to the mast.  Somewhere there will have to be a sealed joint (in addition to the dome seal).

[AngryDonkey]

1 hour ago, Gina said:

They look good but where can I order them from (UK preferably). 

Only found them on AliExpress. Delivery is cheap if you are happy to wait 20 to 40 days (around £4) but fairly expensive if you need faster (e.g. EMS is around £15 which they say will come in 7 to 15 days):

https://www.aliexpress.com/store/product/Factory-IP67-USB3-0-Metal-Shielded-Plug-Mount-Socket-Waterproof-Cover-Electrical-Waterproof-Car-Audio-Vertical/3619191_32859744235.html 

[Gina]

I printed the outer casing shown above but it isn't big enough inside to clear the projection on the camera housing that takes the camera USB connection.  Two possibilities, either simply increase the size or add a "bump" to accommodate the projection.

[Gina]

Radius of protrusion from camera centre line (optical axis) is 60mm.  Current ID of outer casing is 110mm so for a cylindrical outer housing the ID would be 120mm.  I think that's the easiest.

[Gina]

Design changed and now printing.

[Gina]

Start of the design of the bottom part of the outer casing, connecting ASC to mast.

Edited March 16, 2019 by Gina

[Gina]

Base plate and waterblock clamp.  I have yet to work out how USB and other connections will go through this and be sealed.

[Gina]

Mast coupling, base plate with waterblock clamp and camera in housing.  With this arrangement there isn't room for a 4 pin connector for the Peltier TEC and Dew Heater nor for a waterproof USB connector.

[Gina]

Decided I shall use two round cables - USB and a 4 core for the dew heater and camera cooler (Peltier TEC).  They can be clamped between 3D printed flexible plastic pieces (TPU filament).

[Gina]

New baseplate and waterblock clamp plus cable clamp.

 

Edited March 17, 2019 by Gina

[Gina]

Cables clamped and will be sealed with silicone sealant when finally assembled.  The upper casing will be attached with screws from underneath and sealed to the baseplate.

[Gina]

More progress.  Most of the outer casing done - still the dome clamp to be done.  I think the dome may want raising a few mm to get the lens in the optimum position but I think I'll try it as it is (next time there's some clear night shy).  Also some outside work - cut mast tube to length and made hole in the side for cables and water pipes.

[Gina]

I'll start a Blog on this ASC soon but I need to decide on a title.  The version number doesn't mean very much and whilst I'm hoping this build will last a few years, it may not be the last one I make and I certainly can't call it "Ultimate" or anything like that.  Maybe something like "Gina's 2019 All Sky Camera".

[Gina]

Dome clamp ring designed, printed and fitted.

[Gina]

Been pressing on with this project and almost finished the ASC itself including wiring the Peltier TEC and dew heater to the 4 way cable, attaching the waterblock and clamping together all the camera casing parts, and sealing the cables and various parts with silicone sealant.  With clear sly now and forecast for tonight I was all ready to get it up on the mast - just needed the focus setting.  BUT - in spite of having everything working a few days ago, I now cannot get the router to connect to the RPi using Ethernet.  Ethernet sockets show the connection as working but the RPi is not being detected. 

HELP!!

[Gina]

Working again!  Tried a different SD card and that worked so I tried the asc card and that's now working.  Must have been a bad contact.

[tonyowens_uk]

Gina what was that translucent filament you made the exterior casing and dome retainer ring from?

Also have you had any problems with outgassing (acetic acid and moisture) from the RTV sealer on these types of projects involving optical windows?

Thanks

Tony Owens

[Gina]

rigid.ink PETG Natural Clear

Too early to say if there's any outgassing from the sealant.  I've only used it sparingly.

[Gina]

I managed to get a few images with the ASC mounted on the mast which I stood on the ground outside the living room window and supported nearly upright by tying to a heavy tripod (the one that came with the NEQ6 mount) but lost the USB connection, probably at the connection inside the mast tube.  At that point I decided I wouldn't risk the rather less than totally safe support with the tripod.  I think there's a good chance that I shall be able to attach the mast to the side of the observatory and run the ASC from inside the observatory tomorrow.

Here's an image with the ASC about 2.8m above the ground outside the front of the bungalow.

[Gina]

Hole in pipe that forms the mast.  This is for the cables and water pipes used for cooling.  Roughly cut out and smoothed with file but could be further smoothed with emery cloth.  The pipe is 1¾" OD and ⅛" thick.  (If you want it in metric multiply by 2.54 for mm.)

[Gina]

So far today :-

1. ASC assembled, a couple of bags of silica gel pellets included and all sealed up. 
2. Pipes and cables threaded through mast pipe and hole and ASC attached to top of mast.
3. Mast erected and clamped to existing bracket on north side of observatory.