Cooling my classic cassegrain

[doug mc]

Thinking of attaching a small computer fan to the front dust cover on my GSO C.C. Doing it this way with the rear port open should help cool down. What is a good material to use for a dust filter to place on the outside of the fan? Thanks.

[JA]

You could use a couple of layers of filter material used in HVAC systems for homes. Typically white or light grey in colour and 8-10mm thick. Some hardware stores will have it on the roll to buy by the metre.

The image below (from Google) shows how effective it is in trapping dust in a household HVAC system - Take a close look at the top dark grey layer: it is dust with the white filter material below. It's a good advertisement for the benefit of having one in your home as well (usually in the return air).

Best
JA

[Ukastronomer]

As long as it blows OUT and not IN with a load of crap and the air coming in from behind is filtered through the eyepiece holder, and to this end I have made them in the past from this GREAT stuff

https://www.amazon.co.uk/gp/product/B007QUA7N2/ref=ppx_yo_dt_b_search_asin_title?i e=UTF8&psc=1

That slip on and ducct tape, between the circular cutouts, don't laugh, think about it, three layers of fine "Tights", "Stockings" yes......, thin, and the finest make superb fine filters

[doug mc]

Will hunt for that filter material. Thanks JA.