Dew Shield and Dew Heaters

[Striker]

Hi all,

As you are probaly aware the factory branded dew shields and Dew Heaters are very expensive for what you get...most serious astronomers build their own......

Any tips on what to use and how to build both of these product....I have already spoken to Westsky who builds his own but what does everyone else use or have built?

[mch62]

Now why on Earth would you want these items for??:whistle: :D :P

[Vermin]

Nichrome wire or a string of power resistors and some method of controlling the current flow is all that is required. There are quite a few DIY web pages out there if you are handy with a soldering iron:

http://www.olle-eriksson.com/Default.aspx?page=Article&id=116
http://www3.sympatico.ca/mark.kaye/dewheat.htm
http://mysite.verizon.net/res0owmd/id1.html

Try Google for more.

[gbeal]

Like Vermin says, nichrome, and contrary to what he says an electrical dunce like me can (has) done it. I simply sourced a suitable gauge of wire, and at a suitable length to go with the power supply I use (12 volts). In most I make it a semi permenant fixture, by sheathing the nichrome, and attaching it with electrical tape, in a neat fashion. Wires leading from the nichrome to the other heaters all finish at a plug, and this gets fed to 12 volts. The only trick is the right length/gauge to allow a warming, and alo the fact that you can't solder Nichrome, bummer.
Gary

[Striker]

I have finished my first attempt at a dew shield.....I rung up my trusty people at Dyman Foams and they sell matt black close cell foam in sheets 2 x 1 meter 1 cm thick.....$17...then I went to Bunnings and got some heavy duty Velcro for $8....with this amount of foam I can make 3 dew shields......not bad for about $10 total each......
Total weight is feather like....

Funny that Clark rubber wanted to charge me $55 for a piece 1 x 1 meter for the same stuff..........talk about mark-up......grrrrr

Anyway here is my first attempt.....positive and negative comments welcomed.

http://www.users.on.net/~striker/Dew%20Shield%201.jpg
http://www.users.on.net/~striker/Dew%20Shield%202.jpg

[westsky]

looks good tony, now go make a dew heater, you are going to need it:-))

David.

[ballaratdragons]

I can't purchase any foam like that out here. Clark Rubber shut down but have announced they are opening a new store in a few months.

Thay are the only foam supplier without going to Melbourne.

[mick pinner]

Hey Striker,
I'm currently having a dew shield made by a local engineering shop,it will be made of stainless steel with three attaching thumb screws so they will look pretty much like the originals, i'm going to paint it Meade blue which l have already matched.
Once it's done l'll post some pics, if anyone's interested l can get some more done they estimated a price of about $100 ready to prime and paint, not bad compared to Meades $450 or thereabouts.
Mick

[Striker]

Sounds good Mick $100 is cheap......but hows the weight considering its stainless steel.

[mick pinner]

The stainless steel is only 0.6 mm thick so therefore it is fairly light but also very rigid it will also act towards being a balance for any accessories mounted at the viewing end. Mine is being made 400mm long but can be made to owners requirments.
Mick.

[gbeal]

Nice shiled(s) Tony, I too have used this sort of material, and an added bonus is the fact that it keeps your "soon to be made" dew heaters heat in. Makes it more effective.
Gary
P.S, As Robby for a picture of his C8 dew shield, it shows how old he is, psycodelic (is that how you spell it).

[Robby]

A real Dew Sheild.... Here you go Gary! :D

[gbeal]

Man that is sick, my old alloy bar looks definitely out of place.

[ving]

woah man! thats a trippy colour scheme you have going there! :thumbsup:

[Striker]

Haha Robby......nice colour scheme.....but wouldn't those bright interior colors reflect some light........dont you want it to be a matt black interior.?

[bytor666]

heyyyy....STRIKER !!!! thats a great dewshield you've made there!!!!...I remember going to a telescope store & they wanted over 100 bucks for a dew shield..!!! I was like WHOA !!! forget that noise !!!!....so , I went out and got some insulation stuff at a hardware store and lined it with a felt-like material...I agree that a LIGHTWEIGHT dewshield is far better than some heavy thing that will just cause the scope to take a NOSEDIVE !!!!...here is a pic of the one I've made for my 12 " GSO scope.....cheers !!!!
-----------------------
Markus
12" GSO SCOPE

[Starkler]

Markus I'd like to do similar for my dob.
How is yours held on ?

[Striker]

Nice one Marcus...you know your scope could be mistaken for a canon....lol

[Astro_Guy]

There is a US based company called Astrozap that makes both the flexible foam and rigid metal dew shields. The metal ones are available in colors to match your scope. Recently they have introduced a flexible model, similat to that shown as the "Striker Shield", with built in dew heater. They call it the "Flexi-Heat" dew shield. It sells for $74.95 US in the eight-inch size, $85.95 in 9.25 inch, $92.50 for the ten-inch, etc. The problem as you might imagine is that these ship in fairly large boxes, so the shipping charges to Oz could be a real killer.

[bytor666]

Hey Starkler !!!!.....this dewshield is held on simply by using "VELCRO" on the bottom. I stretched it around the tube as tight as I could , then I made a line with a marker and I put velcro with adhesive to hold it in place....LMAO!!!my neighbour used to see me setting up in the yard and she said " oh hes getting ready on his launching pad", then I invited her & her husband over for a peek at jupiter because they didn't believe it was a telescope !!!!!....HAHAHAHAHAH
-------------------------
MARKUS
12" GSO SCOPE

[Striker]

I did the same........Bought Heavy duty Velcro from Bunnings.......But dont rely on the adhesive......I added my own glue and it is as strong as.....Its actualy really hard to pull apart...that HD velcro is incredibly strong.......

[ving]

its only holding a bit of foam... how strong does it have to be?

[Striker]

No the point is......the velcro glue will not bind to the foam very well......meaning that due to the strength of the velcro bind...first time you pull it apart the velcro will come off with it....thus the reason for the adhesive......

[ving]

oh... just trying to figure out why the super duper velcro as opposed to normal...

[Striker]

Probably no reason at all Ving but it was only $2 more expensive then the pre packaged velcro.....some cheap velcro doesn't hold to well neither does it last long.....

[gaa_ian]

As an alternative ... Sirus Optics in Brisbane have the "Orion" brand of dew sheilds @ aprox $50 for a 10" scope.

[[1ponders]]

OK, for all youse out there that got a good cackle at my innovative attempt at removing dew using the *waste* heat of a laptop, there by value adding what would normally be thrown out, I've succumbed to the pressure (of dew, not you). I searched everywhere on the coast for a 12V hair dryer but there was not a one to be had anywhere. But look what I did find :D A 12V ceramic heater fan, specifically for demisting car windshields. So :P (I still liked my laptop idea. If only the fan was stronger)

[Striker]

How much paul.......$

[[1ponders]]

tirty foive bucks :) Cheaper than a hairdryer too. And doesn't give the wrong impression. :P

[RAJAH235]

Ken & all, have you tried any air conditioning firms? When they ship/transport their galv. ducting, it's usually wrapped in *closed cell* black/grey foam about 5mm thick. It's free as it is normally thrown away. This is what some of our members have used as their D/Ss. A long piece of 1" wide elastic with velcro at ends is used to wrap around the tube, or attach the velcro to the edges of the foam. Just a thought. L.
ps. Paul R, Did you try a camping/caravan type store?

[[1ponders]]

that's where I picked up the demister Rajah. The guy there had heard of the hairdryer but didn't stock them. Beside this will double as a tent warmer when I'm snuggled up out west in winter.:D