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DIY $10 SCT Cooler

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#1 Rick-T137

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Posted 21 August 2016 - 04:33 PM

So, I had some free time today, and decided to build a DIY cooler for my Meade 2080. After some Googling, I figured I didn't have the expertise or skill to build something like the Lymax cooler, but I did find some great articles, and one that caught my attention was Piotr Maliński's blog post about how he built a blow-through cooler. Here is his link: http://www.rkblog.rk...ade-sct-cooler/

 

The idea is simple: hook a 12V fan up to the visual back, and remove the screws around the primary mirror casing that would be used for mounting a dovetail bar or other accessories. The fan will draw air into the OTA and it will vent out the screw holes. I asked my son if he had any derelict PC's laying around, and he provided me a 12V DC 3 inch chassis fan. I then dug up a car accessory cable that had been chewed by my cat (meow!) and hooked the two together. Plugging it into my power pack, I verified the fan runs fine.

 

I then went to the hardware store with $10 and came home with two parts from the plumbing area:

  • 3 x 1 1/2 ABS reducer
  • 1 1/2 x 1 1/4 adapter

That's it! Went back home and hooked them all together with black duct tape. I added a used dryer sheet to the back of the fan to keep dust and debris out of the OTA and hooked it up. PRESTO! A steady stream of air from the 6 screw holes around the back of the OTA. I would expect this will reduce the cool-down times of my scope, and all it cost me was $10 and some effort.

 

I'll let y'all know how it works out. :)

 

 


#2 bartine

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Posted 21 August 2016 - 06:04 PM

Interesting!

 

Can't wait to hear how it works out.

 

You might want to put a piece of thin cloth around the holes so no dust or insects get sucked in.  You'd still get plenty of air coming through.

 

I wonder if you could somehow hook a Peltier chip up to it somehow to blow the cool air across to super cool it.



#3 Rick-T137

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Posted 21 August 2016 - 06:22 PM

The tiny screw holes are where the air exits, so hopefully nothing gets sucked into them! But that's not a bad idea to rig up a little mesh or perhaps more dryer-sheets.

 

Super cooling? I think that is a super cool idea! I do have a Peltier chip on my old SBIG ST-237A - but I doubt that I'll take it apart for this purpose.



#4 cam1936

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Posted 21 August 2016 - 06:40 PM

I don't know how wise blowing cooled air into the telescope is. If the air is lower than the dew point you are going to be pumping moisture in there.

#5 Rick-T137

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Posted 21 August 2016 - 07:11 PM

Well, I guess I'll find out if that is an issue! I'm thinking of using this gadget in the winter when the temperature differences are bigger. You may be right that I wind up dewing up my optics - but I don't think that'll happen. I'll let you know! :)



#6 cam1936

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Posted 21 August 2016 - 07:23 PM

Sorry. I meant I don't think blowing air cooled by the peltier cooler is wise, as the air temp would be lower than ambient. Blowing ambient air into your scope with your cooler as designed will be fine.

#7 Rick-T137

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Posted 21 August 2016 - 07:26 PM

Oh beauty! Sorry - I misunderstood. :)



#8 Rick-T137

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Posted 23 August 2016 - 09:59 PM

So I got to try my "Plastic Fantastic" out tonight. I set up my 8" SCT at my dark(ish) sky location just after dusk. By the time I had everything ready to rock, it was getting pretty dark. I tuned my Telrad and 8x50 finderscope with Deneb, as it was in a comfortable position in the sky. Through my 15mm Plössl (133x), Deneb was a roiling, boiling blob. Not too impressive.

 

I pointed my OTA towards the ground, removed 6 small Allen bolts from around the mirror end, and inserted the DIY cooler into the visual back. Flipped it on and set a timer on my bberry for 10 minutes. During that time I went to my star charts and planned my course for the night (M13, M27, M57, M71 and Rasalgethi). The timer went off, I replaced the Allen bolts and it was time to check things out!

 

I put the 15mm back in, zipped back to the target and now Deneb was a crisp, round star. No roiling, no boiling. Nice and steady. I popped in my new Fujiyama 6mm Ortho (333x) and I was rewarded with a nice airy disc with one bright diffraction ring and a couple of fainter ones. Very pleasing!

 

So, there you go. It appeared to work well. Not bad for $10!



#9 Traveler

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Posted 23 August 2016 - 10:45 PM

In 10 minutes? Great job!.

Maybe something like this will also work for a Celestron SCT.



#10 Rick-T137

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Posted 23 August 2016 - 10:50 PM

In 10 minutes? Great job!.

Maybe something like this will also work for a Celestron SCT.

 

The temp difference tonight wasn't huge, so I think that's why 10 minutes worked. My plan was to run it for 10 minutes, check it, then run it for 10 minutes more, etc. But it was great after the first run! I would expect it to take longer if the temp difference was larger.

 

Unless you're willing to experiment with your equipment (as I am), I'd recommend buying a ready-made product like the Lymax Cooler or Tempest Fans.




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