Self made cat/SCT cooler - some questions

[riklaunim]

I have C11 now and that baybe has primary that needs some time to cool down. I'm thinking about some fan cooler to make it faster. (2h wasn't enough to cool it at ~-10C night). There is Geoptik cooler for 180 EUR :

I'm thinking about making something myself. A box - one side fan sucking air, and second - SCT thread (visualback). Inside the box - some filter (foam and something more?). The air would go out through holes in the OTA and 4 holes at the top of the OTA by the finderscope (unscrewed redundant screws). Without the tube and letting the air out through visualback. Advantage: air movement by the primary + nothing going inside the scope.

Does this idea is good? What should be used as dust filter. Simple foam filters isn't enough I think + I could add some desiccant pellets. I have one 12V twin bladed fan that can do 147,64m3/h by the docs + some slower ones.

Basic filter. More needed

(I just hope C11 will perform good, and I won't regret getting it and not Tal250K )

[nathkrul]

look at my thread here m8, all made from stuff you can buy from B&Q.

http://stargazerslounge.com/diy-astronomer/98388-home-made-cat-cooler.html

Colin

[riklaunim]

I'm doing something similar. I should have some pics today if everything will glue correctly

[riklaunim]

Cat Cooler home edition | Flickr - Photo Sharing!

A fan blowing through 2 foam filters to a box with a SCT visualback with a microfibra layer as a filter on the oposite side (no extra holes). That is screwed to the SCT back and should push the air through the whole OTA Should be ready for tomorrow.

[nathkrul]

how does the warm air escape from the tube? as I dont see a long tube fitted to the cooler..

If you look at most cat coolers they all have a narrow tube that goes into the visual back and the air escapes past the long tube and out through the back..

Colin

[riklaunim]

In my design the air is pushed through the whole OTA. It escapes through all those small holes and through holes from unscrewed mounting screws by the finder.

When I unscrewed those two screw the air flow was quite strong and the cooler should be able to push ambient air quickly and make strong current limiting boundary layers on the primary mirror - making it cool quicker.

[nathkrul]

Ah! I see. spot on m8. well done.

Colin