G'day :-) Here in SEQLD during winter, the air's cooling gradient becomes quite steep once the sun goes down. After I put a temp sensor on my (Skywatcher conical) 14" primary I learnt that my mirror has no chance of matching the rate of temp drop (which explains nicely why my planetary views are crap atm!). I cannot install any fans to help the mirror cool due to: a) the unique Skywatcher conical mirror mount; and b) the extant tailgate on my dob is solid, thick plywood
Soooooo, I'm making a new tailgate but one that's more like the 'standard' Obsession style metal frame, although, my conical mirror mount makes it look a bit different! There's probably a dozen different ways to achieve the same outcome but this one will do for now. I'll be finishing it this week, and hopefully, trialling it next weekend with two or three fans installed. I've attached images of the basic design, welding jig, finished (very) raw tailgate and current tailgate. Fingers crossed
Alex