Good Morning to everyone
I have a question regarding homemade dew shields. My current one is made of black cardboard and is doing the job as well as any shop product. The only problem is with it's life expectancy which I suspect will not be too long in a cold winter environment.
I would be interested to know what materials other members with homemade shields use
I have made one from "camping mat" foam. I chose this material because:
Camping mat foam has a closed cell construction so will not absorb moisture
It is very light weight
It has a good resistance to tearing and crushing.
Once I had it cut to size, I used a router table to rebate the two edges where it would be joined, to half thickness on opposite edges, and then used some contact adhesive to bond the stepped edges together. I still have it 10 years later! In theory, you do not need to rout the edges, as I'm sure that contact adhesive will allow you to make a strong butt joint.
I have also used the plastic material from computer paper binders, and used contact adhesive and staples to form a nice cylinder. I taped up the staples to make sure they did not scratch the OTA.
Right now, I have an Orion 10” SCT dew shield for my C9.25, whose advantage is that it can be “un rolled” by separating the Velcro strips and can thus be transported as a flat sheet rather than a bulky cylinder.
I'll second the camping mat material. I have one that is velcroed down the side. When not needed its easily stored by wrapping round the lower half of the OTA.
I have also commonly use manilla folders for the Telrad and opposite the focuser and accept that they will only last a few months.
Thanks Dennis & Rob
Camping mat foam is one material I didn't think about, and it sound like a really good medium
I'll have to pop down to the rubber and foam store tomorrow and get some.
I have actually just made a "mat" dew-shield today (sorry - yesterday, it's past midnight). $14.95 for the camp mat at K-mart, it was dearer than that at the camping stores, etc.
I have used a black plastic garden pot that is the same diameter as the tube.
If you hunt around you can find one that is the same diamter as your scope.
You need to make 2 cuts across the top and bottom and then just attach some velcro around the rim part. Mine cost about $8!
Good Morning to everyone
I have a question regarding homemade dew shields. My current one is made of black cardboard and is doing the job as well as any shop product. The only problem is with it's life expectancy which I suspect will not be too long in a cold winter environment.
I would be interested to know what materials other members with homemade shields use
Hope everyone has a great weekends viewing
Ric
Try Coreflute Ric, you know the stuff they make real estate sale signs out of you can by it allready black, bends well in one direction only. I have been only able to get it with the bendy dimention at 1.2 meters, so If you have a 14" its too small. cheep as chips plastic, and pretty cool stuff, literally,,''
Super glue at the seams works really well,
shawn
interesting topic, i have two methods i use- 1) depending what size, i use something like a gutted out coffee can, sanded and painted with flat black on the inside, mine 'slips' over the OTA and held in place with 1/2" foam compression on the inside of the dew shield- i made 1 with a false spider assembly on the front for refractors to imitate spider vanes of a newt (image thing)- 2) other type for larger like my SCT is coil stock, not sure what you call it there but its rolled aluminum sheeting used in soffitt and fascia, its just rolled and riveted into a tube about 1/2" larger then the OTA- add the same compression tape and slip it in on and off- to cover the metal ends i used a black 'door guard' from an auto parts stores, my SCT is a celestron so i painted it with a hammerite dark gray finish-99% identical match to celestron gray- inside is ultra flat black, i didnt want to fuss with flocking paper on the larger shield- john
Campers foam mattress= about 1cm thick rap around the tube, cut exactly to size, liquid nails on both ends, when dry put together. Works well on my 14" SCT, but will still due up in high humidity, so built my own resistor heater=no more problems.
Thanks to everyone for their suggestions
I've decided to go with the camping mat technique and glued the mat together with a foam/rubber glue, I also glued a strip of heavy cardboard down each side of the join for extra strength.
I even had enough left over to make a Hartman mask and a dew shield for the finder scope as well. They are all working well and all for $31, not too bad at all.
