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My DIY Dew Shield for 8" LX200

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#1 drbyyz

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Posted 16 December 2012 - 02:45 PM

Decided to make myself a dew shield to avoid using a hairdrier on those dewey nights and to block out some stray light from the streetlights I can't get rid of at my home site.

Found a cheap sleeping bag mat at Wally World for about $7 bucks. Cut it to fit the scope, might cut it lengthwise now too as it's a little long, but we'll see. I think this material will work out well, it's waterproof, slightly insulating and very, very light.

Used 2 heavy duty velcro patches to fasten it into the tube shape around the scope. These seem to hold it on really well with no need for any other fastening device. We'll see how it holds up to a field test soon.

For the inside I hot glued some black felt to reduce light reflections, scattering, etc. This is the part I'm slightly disappointed with at the moment, the felt doesn't sit very flat on the curved surface, and bunches up in places. Don't think it's bad enough to block any light entering the scope, but I just don't like the messy look. As a note, super/gorilla glues will NOT work for this project. They only get absorbed by the felt and don't stick to the mat. Hot glue holds it on there pretty well.

Next project is the dew heater/controller. I've already made the heating strip, working on the controller now. Will post when completed(or at least closer).

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#2 drbyyz

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Posted 16 December 2012 - 02:48 PM

Lol, you can actually see my old "dew shield" in the background. It was also a sleeping bag mat, but very heavy and I fastened it on with bungee cords.

#3 Christopher Erickson

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Posted 16 December 2012 - 05:23 PM

Darken the inside!

#4 drbyyz

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Posted 16 December 2012 - 05:48 PM

Darken the inside!


I did, lined the interior of it with black felt.

#5 Digital Don

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Posted 16 December 2012 - 09:19 PM

Great minds think alike!

I made something similar for my C11 20 years ago. I'm still using it today with my CPC 1100.

I cut half-lap joints in the ends and secured them with hot glue. Since the interior surface is so irregular, I never found it necessaary to darken it.

Works for me!

Don :usa:

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#6 davebl

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Posted 18 December 2012 - 12:22 AM

I used the same thing for my 14" LX200 GPS and it works great. I actually used flat black spray paint on the inside. Goes on easy and sticks good.

Dave

#7 CharlesW

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Posted 18 December 2012 - 11:59 PM

As for applying the felt, 3M has a spray adhesive that will do the job-Lowes/Depot/ any auto parts store. A yoga mat would also do nicely. Dirt cheap at Marshals. I like the half-lap joint.

#8 Starman27

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Posted 19 December 2012 - 09:15 AM

Ok! I found some of the material in the basement and will try to make one for my 14 inch.

#9 jgraham

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Posted 19 December 2012 - 09:33 AM

Cool beans. For my smaller ETX-90 & 125 I made my dew shields using thin sheets of black foam rubber from an art supply store. For my LXD75 SC8 I used aluminum flashing bonded with pop rivets and flocked with black construction paper. The shield is secured with four small tabs of Velcro.

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#10 drbyyz

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Posted 01 February 2013 - 09:12 AM

Darken the inside!


I did, lined the interior of it with black felt.


The felt ended up not working out to well, I never managed to get it to lay flat and it kept coming off. Easy solution, ripped it out, went to WalMart and picked up a can of flat black spray paint. It adhered very well, is very dark, and appears not to be very reflective(tested with a fairly bright flashlight).

Another option I've though about but haven't tried is that black sealant stuff that's been advertised on TV a lot lately...you know, the one where they put a screen door in the bottom of a boat, spray the stuff on and it floats. I think it might be a little too reflective but it might make for a nice waterproofing first coat if you made a dew shield out of a cardboard concrete tube, which I've seen many people do.

#11 KangaBear

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Posted 10 February 2013 - 06:42 PM

Love your work guys. I have a LX200 10" ACF and I will make one as well. Its so simple!!

#12 QS3000

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Posted 19 February 2013 - 02:56 AM

I made mine a couple of years ago and it still looks, feels and works as new. It is 29 cm long and weighs only 278 grams, thus allowing other useful equipment to be loaded on my 8-inch scope.

That "silvery" material is simply insulation foam that you buy at a hardware store. I needed only a small piece but I had to buy the whole package from Home Depot for $10 back then. Using a "Gear Driven Ring Roller " (sold by Harbor Freight) I made two rings from 0.5-inch wide aluminum rail also bought at the Home Depot and glued their slightly overlapping ends with epoxy glue. Someone with the proper equipment could weld the ends of course.

I mounted the foam on the rings with double sided tape (by 3M), covered the connecting edges of the foam with aluminum tape used in kitchen exhaust fans, and then added transparent packaging tape on top of the aluminum tape for extra strength.

Finally I applied a couple of layers of black felt inside. That was the most difficult part of the process. Obviously I had to make the rings slightly bigger in diameter than my scope's rim. A lighter's flame was used to smooth the felt on the side of the shield that attaches to the scope.

On a night with lots of dew you can actually feel the humidity on the felt after the observing session is over. By the way, that "Gear Driven Ring Roller" is extremely useful if you want to make your own aluminum mounts for equipment that attaches to the back rim of a 6", 8", 10", etc scope.

DrF

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