Dob stored in hot shed.

[jjjnettie]

My astronomy gear is kept in a tin shed.
The spare computer is in this shed as well and it hates it. It has me worried about the scope now.
When is a shed too hot for storing a scope?
What damage can it do in the long term?

[ving]

dob on a hot tin roof....
melt the grease? warp plastics? melt adhesives?
thats all i can think of.

[jjjnettie]

I'm already having to glue some of the laminate back onto the base. I think it was AstroRon that told me to seal all the laminate joins when I first got the dob. Would a coating of shellac do the job, or what should I use?

[xstream]

A Hot dry iron will reactivate the glue on the laminate.
I would then seal the joins with silicone.

[Robert_T]

I haven't tried this but it might help to glue in some "batts" or some other insulation into the ceiling of your shed and/or install one of those rotating vent thingies if the roof has a peak?

cheers,

[rmcpb]

Make sure your shed is really well insulated. Mine is a bit modified in that I have put large eves on it and insulated the roof heavily and now the deciduous trees around it are growing up nicely which will help keep it even cooler in summer. Even without the trees the insulation works wonderfully.

[iceman]

Not just the joins etc, but it's going to take much longer to cool down when you actually want to view through it, if it's stored in a hot shed.

[Satchmo]

Metal ( ? ) sheds are tricky places for optics as ideally they are not insulated and your optics can often end up coated in water every sunrise and depending on the prevailing weather conditions and time of year , and may not adequately dry off every day. Large optics suffer from this problem . A 15 watt light bulb mounted on a wooden plate in the mirror box can help. However you want the shed to get rid of its heat fast at sunset, so insulation in the walls isn't good . Unfortunately the requirements for a good observing location and scope protection are actually in conflict I'm afraid !

Mark

[rmcpb]

As well as an insulated roof mine is up on an elevated wooden floor allowing for good all round ventilation. So far there has been no problems with condensation. The walls are not insulted so its pretty close to ambient inside all the time.

[hogly52]

In my "donga" (where my scope is kept), if I leave the air-con off, daytime temperatures will rise to around 36 degrees. So far, I've had no problem in being able to come home, grab my gear and go out observing. No heat problems thus far, including the laminates. At the moment our overnight temperatures are still quite warm, so there's not a big temperature variation during my observing times.

If I've had the air-con on, say 22 degrees, I get fogging on both mirrors as soon as I take the scope outside. The lesson for me is that if I think I'm going out observing that night, the air-con is left off. If I forget, like last night, I make sure the air-con in the car is off and the windows are open to ensure any fogging is evaporated and the scope reaches ambient temperature by the time I reach the viewing site. Unlike most on this site, I have to ensure the scope is brought up to ambient temperatures, not the reverse.

In general, I don't believe natural heat or cold should affect the scope or optics. Yes, sudden changes in temperatures or formed moisture will. Avoid extremes, sudden changes and clearly adverse environments and your scope should provide the results and enjoyment you expect. Give it some extra care and respect, if in doubt. Better to err on the cautious side.

Cheers :drink:
Graeme

[jjjnettie]

I keep the scope zipped up in a sleeping bag. Maybe if I use two it will keep it better insulated against extemes.

[rmcpb]

That will slow the speed of the temperature change but not the actual temperature peaks and troughs. I don't believe the temperature changes will cause any problems with your actual scope except for time to equilibrate with the ambient air when you want to observe but that is easily fixed in the standard way of leaving it outside for a while.

The high temperatures will possibly affect your mount more than the scope. The temperature sensitive glue is most likely to start letting go and not looking good. Reattaching with an iron will work for a while but, if you cannot insulate your shed to help keep the temperature down, a new painted plywood base may be in order then the temperatures will not matter one dot.

[jjjnettie]

When I first put the scope together, I knew that I'd have to ditch the chipboard base at some stage.
You could salvage most of the parts from the original to use in the new one.

[ballaratdragons]

1 sheet of plywood and use the original base parts as a template. Seal the new plywood base with heaps of clear! and Bobs your Uncle.

[gaa_ian]

My 10" GS Dob has been outside on a verandah (insulated roof) for 3 yrs in the tropics.
It is only showing slight signs of swelling in the chipboard (good for another yr or 2)
Ken, what thickness of plywood would you use ?

[rmcpb]

I recon I would go for at least 19mm ply to make the base good and strong.

[jjjnettie]

You could cut the platters a mite bigger to make it more stable. I'd feel tempted to get out the pyrography pen and tart it up a bit before sealing.