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Thread: Cooling of Newtonian Optics - all fans are not created equal

  1. #11
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    Default Re: Cooling of Newtonian Optics - all fans are not created equal



    All interesting ideas, for the site selection I am choosing from locations in my backyard, because that's where I am
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    Is there a poor mans way of generating air movement in the area? I am wondering about setting up a fan a few feet (10-15) from the
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    at low speed and moving air across the gear that way. Is that likely to have any positive effect, or negative effect? A quick search of what is available commercially for Newts seem to start with 8" models and up, leaving my 6" model feeling a bit left out. Would generating air flow in the area have any useful effect at all?

    And my initial question remains - better to leave the end cap on to prevent light leak, or take it off to allow air flow? I am not interested in DIY solutions, because DIY is not a strong suit of mine.

    Bob
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  2. #12
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    Default Re: Cooling of Newtonian Optics - all fans are not created equal

    Bob, I can only suggest that you try a couple of nights with the rear of the tube exposed.

    One idea that's occurred to me is leave the rear of the tube open for half and hour to an hour, with the top end of the tube tilted upwards, not totally vertical so dust doesn't settle on the primary, but encourages heat to move. Once the
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    has cooled you can cover the rear again.

    If possible, you might like to put a cuff around the outside bottom end of the tube made out of black thin foam rubber sheet or something similar. This acts like a tube extension and helps shield the mirror, and you can keep the rear of the tube open. I know you aversion to DIY, but sometimes there is no choice in order to adapt our gear to each person's individual circumstances/locations. Scope manufacturers cannot make their equipment to suit every situation - that's impossible. There is no getting around needing to implement one's own innovations to deal with the conditions you have.

    As an example, one of the 8" dobbies I have is a solid tube scope, and is the dobbie I use from home. My backyard is lighting challenged, and the tube is painted white - worst freaking colour for an OTA!!!! So, to combat the blasted shiny white problem, I wrapped the top end of the tube in the thin black foam rubber I described above. Works a treat
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    Alex.
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    Default Re: Cooling of Newtonian Optics - all fans are not created equal

    Is it better to suck or blow?
    I can see benefits and potential disbenefits either way.

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    Default Re: Cooling of Newtonian Optics - all fans are not created equal


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    Originally Posted by SubOptimal
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    Is it better to suck or blow?
    I can see benefits and potential disbenefits either way.
    From what I’ve read in this post, pulling out the bottom would seem to be th the way to go. Either way you have to control where th air goes. If your fan Blows on the back your mirror and sell it will just bounce off and blow back around the fan, Cooling the center of the fan faster than the rest. Without some kind of ducting to move the air around the mirror and across the front, Cooling will be less effective and make cause issues with uneven cooling of the mirror.
    Unless Your statement was meant as humor my response would be “blow is only an expression everything sucks”��

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    10” flextube f4.7 Meade 4400 114mm Newtonian on A GEM.
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