Dew Shield for my 90 mm Mak

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GCoyote United States of America
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Dew Shield for my 90 mm Mak

#1

Post by GCoyote »


I need to get better at documenting what I'm doing so this is as much for me to practice as for the value of the project itself.

As someone else noted, these things really should come with a dew shield.
100 IMG_20201002.jpg
Note the safety cover. That came from a 48 oz grapefruit container. Since I go through one every ten days or so, I can afford to experiment with them.

For the cone: one empty potato salad container.
101 IMG_20200831.jpg
Step one is easy, a small slit with a razor knife around the base to prevent cracking followed by a little scissor work.
103 IMG_20200831.jpg
To cut a ring from the grapefruit lid, I drilled a hole in the center, and used that to cut the correct circle with a stand mounted Dremel.
105 IMG_20200918.jpg
Test fit and scuff the surfaces for painting
107 IMG_20200918.jpg
Problems:
1. I don't have any glue that adheres well to polypropylene.
2. My can of chalkboard black lost pressure

Solution: Flex Seal (as seen on TV) or any similar product. It will stick to most surfaces and will craze polypropylene so that other coatings and adhesives will stick to the new surface. It also makes the outer surface easier to grip with gloves on. The only downside is that it produces a fairly coarse spray and takes up to two days to cure. It took me a week to get the degree of coverage I wanted inside and out.
109 IMG_20200925.jpg
Note: I left the underside uncoated to prevent it from gripping too tightly, It already fits snuggly enough to twist off the front retaining ring of the OTA! May have to sand it a bit.

Test fit.
111 IMG_20201002.jpg
Ready to Rock-n-Roll
112 IMG_20201002.jpg
The rubbery coating is not very reflective but if it turns out to be an issue I can easily add a coating of chalkboard black to the inside.

[Disclaimer: At no point did the cat actually contribute any effort to this project.]
Last edited by GCoyote on Sat Oct 03, 2020 9:33 pm, edited 1 time in total.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Dew Shield for my 90 mm Mak

#2

Post by John Baars »


Looks great!
It will work.
To fulfill the passive anti-dew job, you could isolate the outside of the tube?
Refractors in frequency of use : *SW Evostar 120ED F/7.5 (all round ), * Vixen 102ED F/9 (vintage), both on Vixen GPDX.
GrabnGo on Alt/AZ : *SW Startravel 102 F/5 refractor( widefield, Sun, push-to), *OMC140 Maksutov F/14.3 ( planets).
Most used Eyepieces: *Panoptic 24, *Morpheus 14, *Leica ASPH zoom, *Zeiss barlow, *Pentax XO5.
Commonly used bino's : *Jena 10X50 , * Canon 10X30 IS, *Swarovski Habicht 7X42, * Celestron 15X70, *Kasai 2.3X40
Rijswijk Public Observatory: * Astro-Physics Starfire 130 f/8, * 6 inch Newton, * C9.25, * Meade 14 inch LX600 ACF, *Lunt.
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Re: Dew Shield for my 90 mm Mak

#3

Post by Thefatkitty »


Nicely done; as a DIY'er myself, I can appreciate the effort!

Hope you get some clear skies to test it out :D

All the best,
Mark

"The Hankmeister" Celestron 8SE, orange tube Vixen made C80, CG4 & AZ-EQ5 mounts.
Too much Towa glass/mirrors.

H/A - PST stage 2 mod with a Baader 90mm ERF on a Celestron XLT 102 (thanks Mike!)
Ca-K - W/O 61mm, Antares 1.6 barlow, Baader 3.8 OD and Ca-K filters with a ZWO ASI174mm.
W/L - C80-HD with Baader 5.0 & 3.8 Solar film, Solar Continuum 7.5nm and UV/IR filters with a Canon EOS 550D.

Oh yeah, and Solar Cycle 25 :D
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Re: Dew Shield for my 90 mm Mak

#4

Post by Lady Fraktor »


I do like that! DIY is always a good way to do things. Hopefully it will work well for you.
Just information but well sized dewshields should be 2x the aperture or longer.
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
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Re: Dew Shield for my 90 mm Mak

#5

Post by GCoyote »


Thefatkitty wrote: Sat Oct 03, 2020 9:40 pm Nicely done; as a DIY'er myself, I can appreciate the effort!

Hope you get some clear skies to test it out :D

All the best,
Thanks. Second night of clear skies with a horrendous jet stream tearing overhead. Estimated seeing index is 1/5. grrrr
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Dew Shield for my 90 mm Mak

#6

Post by GCoyote »


Lady Fraktor wrote: Sat Oct 03, 2020 10:00 pm I do like that! DIY is always a good way to do things. Hopefully it will work well for you.
Just information but well sized dewshields should be 2x the aperture or longer.
Easy enough, just need to find a larger container of potato salad! :D
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Dew Shield for my 90 mm Mak

#7

Post by Lady Fraktor »


GCoyote wrote: Sat Oct 03, 2020 10:02 pm Easy enough, just need to find a larger container of potato salad! :D
A bonus from start to finish! :lol:
See Far Sticks: Antares Elita 103/1575, AOM FLT 105/1000, Bresser BV 127/1200, Nočný stopár 152/1200, Vyrobené doma 70/700, Stellarvue NHNG DX 80/552, TAL RS100/1000, Vixen SD115s/885
EQ: TAL MT-1, Vixen SXP, AXJ, AXD
Az/Alt: AYO Digi II/ Argo Navis, Stellarvue M2C/ Argo Navis
Tripods: Berlebach Planet (2), Uni 28 Astro, Report 372, TAL factory maple, Vixen ASG-CB90, Vixen AXD-TR102
Diagonals: Astro-Physics, Baader Amici, Baader Herschel, iStar Blue, Stellarvue DX, Takahashi prism, TAL, Vixen flip mirror
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Re: Dew Shield for my 90 mm Mak

#8

Post by Ylem »


Looks good too :)
I made mine from some foam panels.
Clear Skies,
-Jeff :telescopewink:


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Re: Dew Shield for my 90 mm Mak

#9

Post by goldstar »


Cheap, efficient and a great use of re-cycling.
Scopes: 200mm f6 DOB:CR 6 150 mm f 7.5 refractor, SW ED 80 mm f 7.5. 2 X 80 mm f7.5 guides.
Mount: AVX.
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Re: Dew Shield for my 90 mm Mak

#10

Post by GCoyote »


Update: Tried it out on Mars Monday night with good results. I'm using this scope for planetary so no high altitude/elevation. That makes the length more than adequate.
I did get fresh can of Chalkboard Black and touched up the inside today. Right now the foliage in my yard blocks out most of the odd street lights but reflections may become a problem during the winter months.

Biggest issue was I did not get around to making a dew shield for the Telrad yet so that was a little annoying. Will have to get around to that this weekend.
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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Re: Dew Shield for my 90 mm Mak

#11

Post by pakarinen »


I made mine with a piece of black craft foam I had leftover from another hobby project and duct tape. It slides over the outside of the tube. Seems to work, but definitely not as elegant as yours. And I do love potato salad...
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Re: Dew Shield for my 90 mm Mak

#12

Post by GCoyote »


Heh, I sometimes use friction tape to mount my TelRad to a random OTA. Nice thing about this hobby, very few witnesses!
Any metaphor will tear if stretched over too much reality.
Gary C

Celestron Astro Master 130mm f5 Newtonian GEM
Meade 114-EQ-DH f7.9 Newtonian w/ manual GEM
Bushnell 90mm f13.9 Catadioptric
Gskyer 80mm f5 Alt/Az refractor
Jason 10x50 Binoculars
Celestron 7x50 Binoculars
Svbony 2.1x42 Binoculars
(And a bunch of stuff I'm still trying to fix or find parts for.)
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