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Insulating my SW 180 Mak.

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112 replies to this topic

#51 yellobeard

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Posted 01 September 2018 - 03:21 AM

No Traveler..

If I may answer, the carbon tube is to make the scope lighter, and to minimize focus shift during cooldown.
The carbon 'wall' of the tube is too thin to have any positive effect on the slowing down of the cool down process..
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#52 Cali

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Posted 02 September 2018 - 07:16 AM

What a wonderful do it your self project. I have a 10 dollar coupon from the local Ace Hardware store. 


Edited by Cali, 03 September 2018 - 01:04 AM.


#53 happylimpet

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Posted 03 September 2018 - 06:42 AM

With proper insulation, there should be no boundary layer.  Initially, the temperature of the mirror, the corrector and the air inside the closed tube are all equal. Then, as the entire system s l o w l y cools, it does so uniformly, and avoids the formation of boundary layers. Or, if one forms in front of, or just beneath the corrector, it is as unnoticeable as when one uses a dew heater (which is adjusted properly to the point at which it just prevents dew from forming). 

I realise that - I wasnt referring to anything 'internal'; I appreciate the insulation being discussed deals well with that. I was referring to a putative boundary layer in front of the corrector, in the 'open air'.

 

Happylimpet wrote- "you're now in a situation very similar to that of most Newtonian owners, namely of having a warm-ish optical surface (mirror for us, corrector for you) at the bottom of a tube".  

  "mirror for us, corrector for you"...????  Actually, no.

An MCT/SCT is(!) a Reflector, and has the Primary Mirror on the bottom, same as a Newtonian Reflector. The Corrector Plate is on the Top!

Yes, I know. Same comment as above.

 

I still think this is something worth bearing in mind, even if (I hope) it isnt a significant issue.



#54 elwaine

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Posted 03 September 2018 - 08:17 AM

What a wonderful do it your self project. I have a 10 dollar coupon from the local Ace Hardware store. 

lol.gif Yes. "Customizng" our equipment can be fun. Along those lines, I've decided to go overboard with my next insulation jacket.

 

While I was very happy with the performance of the jacket I made for my TEC 6" Mak, I did not like the look of it. I made that jacket out of a dull, charcoal-gray rubber foam. I thought of using Reflectix instead of the rubber foam mat because I know Reflectix jackets work well. But the telescopes wearing Reflectix jackets remind me of "death rays" out of a 1950's science fiction movie. I wanted to preserve the look of my (new to me) TEC 7" Mak while still employing an insulation jacket. So this is what I'm doing:

 

I bought a roll of a white, dense foam material. It's 2mm thick. I'm using that material to cover the metal OTA so that it provides an air space/insulation barrier between Reflectix and the metal tube. It prevents the Reflectix from contacting the metal tube directly (as per recommendation by the manufacturer of Reflectix). I then wrapped a single 5mm layer of a Reflectix-like material** over the white foam, using a little Elmer's glue to bond the two layers. At this point, this is what it looks like:

 

(This photo is the dew shield. I haven't finished the OTA.)

 

med_gallery_17233_3964_1488524.jpg

 

Then I added a second layer of the dense, white foam material.

 

med_gallery_17233_3964_376019.jpg

 

When I'm done with this project, the TEC Mak will look very similar to it's original appearance.

 

** Instead of Reflectix, I used Prodex. It has 2 to 3 times the R-value of Reflectix, but because it can only be purchased in bulk, it's very expensive ($120 for a roll 4ft x 50ft), so I'd suggest sticking with Reflectix or getting several club members, who want to make jackets for their SCTs or Maks, to split the cost.

 

_Larry


Edited by elwaine, 03 September 2018 - 07:43 PM.

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#55 Cali

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Posted 03 September 2018 - 04:12 PM

 

** Instead of Reflectix, I used Prodex. It has 2 to 3 times the R-value of Reflectix, but because it can only be purchased in bulk, it's very expensive ($120 for a roll 4ft x 50ft), so I'd suggest sticking with Reflectix or getting several club members, who want to make jackets for their SCTs or Maks, to split the cost.

 

_Larry

 

Yes, all materials mentioned in this thread comes in rolls. I'm hoping a good hardware store will measure/cut/sell to a desired length.

 

Please attach pic of your finished project.

Thx!

-Cal



#56 Peter Besenbruch

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Posted 03 September 2018 - 05:31 PM

I was referring to a putative boundary layer in front of the corrector, in the 'open air'.

Interesting question. In my not very severe conditions, I haven't seen a corrector boundary layer, though I did see internal plumes before insulating.


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#57 elwaine

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Posted 03 September 2018 - 07:36 PM

I was referring to a putative boundary layer in front of the corrector, in the 'open air'.

Interesting question. In my not very severe conditions, I haven't seen a corrector boundary layer, though I did see internal plumes before insulating.

 

It is an interesting question. A few years ago there was a discussion on CN about better seeing without dew shields. It was specific to large refractors but it gets at happylimpet's point. This is a quote from that discussion:

 

I keep looking at Arcturus outside of focus to see how the cooling is doing.  I get the swirling eddies that to me indicate there are heat plumes somewhere inside the scope.  I wondered if some of those plumes were "sitting" inside the dew shield so I retracted the shield and checked Arcturus again.  I was surprised to see that the eddies were gone.

 

I have never encountered such a problem with my 130mm APO, with my 6", 7" and 8" Maks, or with my C 9.25 Edge. But like Peter, I have seen heat plumes prior to using an insulation jacket.


Edited by elwaine, 03 September 2018 - 07:39 PM.

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#58 Cali

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Posted 04 September 2018 - 05:59 AM

lol.gif Yes. "Customizng" our equipment can be fun. Along those lines, I've decided to go overboard with my next insulation jacket.

 

While I was very happy with the performance of the jacket I made for my TEC 6" Mak, I did not like the look of it. I made that jacket out of a dull, charcoal-gray rubber foam. I thought of using Reflectix instead of the rubber foam mat because I know Reflectix jackets work well. But the telescopes wearing Reflectix jackets remind me of "death rays" out of a 1950's science fiction movie. I wanted to preserve the look of my (new to me) TEC 7" Mak while still employing an insulation jacket. So this is what I'm doing:

 

I bought a roll of a white, dense foam material. It's 2mm thick. I'm using that material to cover the metal OTA so that it provides an air space/insulation barrier between Reflectix and the metal tube. It prevents the Reflectix from contacting the metal tube directly (as per recommendation by the manufacturer of Reflectix). I then wrapped a single 5mm layer of a Reflectix-like material** over the white foam, using a little Elmer's glue to bond the two layers. At this point, this is what it looks like:

 

(This photo is the dew shield. I haven't finished the OTA.)

 

X

 

Then I added a second layer of the dense, white foam material.

 

x

 

When I'm done with this project, the TEC Mak will look very similar to it's original appearance.

 

** Instead of Reflectix, I used Prodex. It has 2 to 3 times the R-value of Reflectix, but because it can only be purchased in bulk, it's very expensive ($120 for a roll 4ft x 50ft), so I'd suggest sticking with Reflectix or getting several club members, who want to make jackets for their SCTs or Maks, to split the cost.

 

_Larry

Larry

 

So you glue the Reflectix-like material to the foam material to make a jacket.

 

Question. How do you adhere the jacket to the OTA? Velcro?

 

Also, can you provide a link to the type/thickness of Reflectix material which may be used for this project? Here is a link to their site . I have no experience with the material in question. Also, I already have a commercial dew shield. Am I correct to assume it would not have to be wrapped?

 

-Cal



#59 elwaine

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Posted 04 September 2018 - 07:18 AM

Cal, I’d probably use Double Reflectix insulation (5/16”). But I have not actually seen Reflectix myself. I’m basing that recommendation from the info on their website. 

 

If you follow the steps below, the dense white rubber-like foam I referenced in post #54 will hug the metal OTA without the need to adhere it to the tube with glue. (I did not want to use anything on the OTA itself that might ruin the manufacturer’s finish.)

 

I measured the circumference of the OTA and cut the foam to the exact measurements. I then wrapped it around the tube to make sure I had cut it correctly... so that the edges of the foam just met. I then trimmed off about 1/6” from one side so that there was just a small gap between the two opposing edges of foam. The foam stretches just enough to close that small gap using finger pressure in a pincer motion. After closing the gap, I used small strips of white duct tape to join the edges of the white foam. Closing the gap causes the foam to hug the OTA with enough force to hold it in place without sliding on the metal OTA. 

 

I didn’t want the individual layers of insulation to slide over one another so I smeared a little glue here and there on the aluminum surface of the Prodex (Reflectix) before wrapping it around the white foam. (There is no need to cover the entire surface with glue. A spotty job is all that’s needed.) I used white duct tape to join the edges of the Prodex (Reflectix). I allowed the glue to set for a few hours. I measured the circumference again, cut another piece of foam to exact measurements but only used glue. I did not use a gap this time to tighten the foam because the glue adheres it to the aluminum surface of the double sided insulation material. Once again, I used duct tape to join the edges of the foam. 

 

I insulate the dew shield, but that may not be necessary in your environment. 

 

_Larry


Edited by elwaine, 04 September 2018 - 11:42 AM.


#60 Joe1950

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Posted 04 September 2018 - 09:24 AM

I found a roll of the Double Reflectix insulation (5/16”) at one of the home stores. Can't recall which, but it wasn't expensive for a roll.

 

The 'Double' type has the foil on both sides. 

 

I'll use one layer of the Reflectix and two layers of the closed cell packaging material to form a space and to contact the tube.

 

My scope is a 127mm and I expect this to be plenty, Just have to be thorough and cover everything as well as possible. If it works well I may make a matching jacket and pair of gloves.


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#61 doug mc

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Posted 04 September 2018 - 09:06 PM

With all that foil coverage you should stay out of range of alien abduction.😃
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#62 Cali

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Posted 04 September 2018 - 10:49 PM

 

I found a roll of the Double Reflectix insulation (5/16”) at one of the home stores. Can't recall which, but it wasn't expensive for a roll.

 

 If it works well I may make a matching jacket and pair of gloves.

DO post a pic of the matching jacket and pair of gloves. Bonus points if you make a hat.

 

-Cal


Edited by Cali, 04 September 2018 - 11:04 PM.

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#63 Joe1950

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Posted 05 September 2018 - 07:21 PM

And pointed shoes, while I'm at it. Things have to match!  smirk.gif

 

 

One good side light of all this is if one of those cars with the blinding blue tinted headlights comes down the street, they'll get a dose of their own medicine!

 

Not that I wish them harm, but those lights can really ruin one's night vision.


Edited by Joe1950, 05 September 2018 - 07:22 PM.


#64 Cali

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Posted 05 September 2018 - 09:20 PM

 

 

Not that I wish them harm, but those lights can really ruin one's night vision.

Joe

I purchased a pair of these. I was skeptical but the first time I wore them I had forgotten to flip the dimmer tab on my rear view mirror. Sure enough, someone pulled up behind me with their bright lights on and the glare in the mirror was greatly reduced. I also find it less fatiguing when dealing with oncoming head lights when driving for long periods. They don't eliminate all glare but I find that they reduce the really annoying stuff. As always, YMMV.

 

-Cal


Edited by Cali, 05 September 2018 - 09:42 PM.


#65 Joe1950

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Posted 05 September 2018 - 10:58 PM

Certainly worth a try, Cal! A friend uses those to drive at night and says they help a lot. 

 

With my my neighbor having dual 500w flood lights, flooding my entire observing area they may even help there. The light is so blinding I sometimes can’t find the eyepiece. Or I have to try and locate myself in the shadow of a tree trunk.

 

Thanks, Cal !



#66 Cali

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Posted 06 September 2018 - 09:55 PM

This thread has been concerned with taking a Mak from a warm environment to a cooler one. Here is my question. When living in Chicago it was not uncommon during the Dog Days Of Summer to have evening temps in the 80's or even the 90's, so the air conditioning would be running. Assume you keep your Mak in an air conditioned environment (indoors) and then transition it to a warmer environment (outdoors). Do you need a "warm up" period for the Mak because cooler air is trapped in the OTA? 

 

Thanks to Frank for planting this seed in my blunted little cranium. 

 

-Cal 


Edited by Cali, 06 September 2018 - 10:10 PM.


#67 Joe1950

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Posted 06 September 2018 - 10:04 PM

Yes you would, Cal. Regardless if the temperature is lower or higher than where the scope has been sitting, it needs time to adjust to the ambient temperature.

 

However the jacket would work in both cases. If the air inside your Mak is cooler than the outdoor air, the jacket would keep it cool and while outside it would stay that way, warming very slowly.

 

It works the same either way.



#68 Cali

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Posted 07 September 2018 - 04:34 AM

Joe

 

Regarding, "...if the temperature is lower or higher than where the scope has been sitting, it needs time to adjust to the ambient temperature."

 

Question. If I go from from hot to cold, well, you get all the Heebie-jeebies which this thread addresses. But if you go from cold to hot, do you get the same Heebie-jeebies, that being, do you need a jacket?

 

Regarding: "With my my neighbor having dual 500w flood lights, flooding my entire observing area..."

 

I once knew a grrlllllll who Blinded Me With Science. Needless to say, even though the relationship was Poetry In Motion, it was regrettably short lived.

 

-Cal


Edited by Cali, 07 September 2018 - 05:21 AM.

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#69 Joe1950

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Posted 07 September 2018 - 05:19 AM

Yes, Cal, a jacket would do the job; it would work the same as going from hot to cold. The issue is temperature difference. Which way doesn’t matter. Without a jacket, having it outside for a time adjusting to the difference (the old way) before observing also works.

 

This summer with the AC on, I’ve had to put the scope out for an hour or so to “warm up” before using it.

 

I too have had relationships that have gone from ‘Hot to Cold’ in short time spans. Long term commitals are not the norm in this modern and wonderful world.

 

joe


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#70 Cali

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Posted 07 September 2018 - 05:33 AM

Yes, Cal, a jacket would do the job; it would work the same as going from hot to cold. The issue is temperature difference. Which way doesn’t matter. Without a jacket, having it outside for a time adjusting to the difference (the old way) before observing also works.

 

This summer with the AC on, I’ve had to put the scope out for an hour or so to “warm up” before using it.

 

I too have had relationships that have gone from ‘Hot to Cold’ in short time spans. Long term commitals are not the norm in this modern and wonderful world.

 

joe

Joe

 

I'm curious if going from Hot to Cold produces the same thermals as going from Cold to Hot. Did you actually experience a diff if you did not "prep" the scope? Just wondering?

 

RE: "Long term commitals are not the norm in this modern and wonderful world."

 

I fear we have just opened a whole new can of worms which should be relegated to Here, lest we be banished.

 

-Cal



#71 Joe1950

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Posted 07 September 2018 - 07:46 AM

I just did it as a normal preparation. I never looked at it in detail or measured anything. I put all my scopes out for a while before using just to have them ready, regardless of what or where the temperature is. 

 

Cal, at 68 years old, banishment from anywhere is not a concern! 



#72 cildastun

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Posted 07 September 2018 - 10:35 AM

An interesting thread - I am following it with interest to see whether it is worth a try with my 180 Mak.

 

How effective would a soft flexible cover be I wonder, made from fleece material or similar? Might be a lot more "usable" even if the insulating properties were slightly less..

 

Chris


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#73 elwaine

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Posted 07 September 2018 - 11:45 AM

An interesting thread - I am following it with interest to see whether it is worth a try with my 180 Mak.

 

How effective would a soft flexible cover be I wonder, made from fleece material or similar? Might be a lot more "usable" even if the insulating properties were slightly less..

 

Chris

You won’t know if it will work for you by reading this discussion. You’ll have to try it for yourself. 

 

Whether or not it will work, regardless of the type of material used for a jacket, will depend on whether or not you use enough insulation for your climate. 

 

Based on your location, I think it’s safe to say that without insulation, your Mak is bound to suffer from chilblains. wink.gif

 

_Larry


Edited by elwaine, 07 September 2018 - 11:45 AM.


#74 cildastun

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Posted 07 September 2018 - 05:55 PM

You won’t know if it will work for you by reading this discussion. You’ll have to try it for yourself. 

 

Whether or not it will work, regardless of the type of material used for a jacket, will depend on whether or not you use enough insulation for your climate. 

 

Based on your location, I think it’s safe to say that without insulation, your Mak is bound to suffer from chilblains. wink.gif

 

_Larry

52 degrees N in our island climate is not that cold, far less severe than the same latitude in N. American so we don't have too many nights below 0 degrees here. My Mak is kept outside and is usually ready for use in 15 minutes or so, giving near-theoretical results on many evenings because of the often excellent seeing (on days when it isn't raining!). For example,

 

doubledouble180mak.jpg

 

However, I can usually see a heat plume with an o-o-f star, and sometimes heat bleed effects through the rear plate, so an insulating cover may be worth a try.

 

Chris


Edited by cildastun, 07 September 2018 - 05:56 PM.

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#75 payner

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Posted 07 September 2018 - 08:39 PM

52 degrees N in our island climate is not that cold, far less severe than the same latitude in N. American so we don't have too many nights below 0 degrees here. My Mak is kept outside and is usually ready for use in 15 minutes or so, giving near-theoretical results on many evenings because of the often excellent seeing (on days when it isn't raining!). For example,

 

attachicon.gif doubledouble180mak.jpg

 

However, I can usually see a heat plume with an o-o-f star, and sometimes heat bleed effects through the rear plate, so an insulating cover may be worth a try.

 

Chris

Yep, enjoy that warm, Gulf Stream we pump up your way from our southeast coast.  Otherwise, you'd be in the deepfreeze. <g>


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