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Posts Made By: Craig Colvin

June 25, 2004 04:34 AM Forum: Telescope Making

The problem with lightweight telescopes...

Posted By Craig Colvin
My problem with my 8" f6 string scope wasn't and isn't the wind vane effect. My problem was balance. With a single ring the eyepieces become a higher percentage of the overall weight and covering the range from lightest eyepiece to heaviest was almost impossible. I ended up adding a spring from the alt bearing to the rocker box and now have no problems at all.


June 29, 2004 03:22 AM Forum: Telescope Making

Experience with these kits?

Posted By Craig Colvin
I don't have any experience with these but Pete's kit doesn't look too bad. You will still need to add the cost of the sonotube and wood but it looks like everything else is there.

Of course for that price you could buy a completely assembled Harden 10" dob. So the question is, do you just want to OWN a 10" scope, or do you want to BUILD a 10" scope.

June 30, 2004 12:32 AM Forum: Telescope Making

Dob Caddie

Posted By Craig Colvin
It would be far cheaper and easier to just buy one.

http://internet-trailer.com/DisplayTrailer.asp?id=TRANSPORT

July 6, 2004 10:33 PM Forum: Telescope Making

Question Regarding Mounting Altitude Bearings

Posted By Craig Colvin
That was hard to understand. smile

If you altitude bearings are half circles then line up the top edge of the alt bearing at the height of the balance point and center them on the mirror box.

Basically if the alt bearings were circles, you make the center of the circle be at the balance point. Since they are half circles you make the top edge of the bearing be at the balance point.

-- Craig




July 27, 2004 02:53 AM Forum: Telescope Making

fans - front or back

Posted By Craig Colvin
I would do both a fan blowing across the mirror surface and one blowing on the back. However you need to make absolutely sure that the fans are isolated from the mirror box. A lot of people use a neophrene mouse pad for isolation but I've seen a lot of cases where that wasn't sufficient.

I ended up mounting a fan on the back and put one in the mirror cover to rapidly cool down the mirror. Once it is near ambient temperature the rear fan seems to do a fine job of keeping it cool.


September 3, 2004 02:33 AM Forum: Telescope Making

A New York City Apartment Dweller's Scope

Posted By Craig Colvin
Very nice work.

I went with the single ring on my UTA just so it would fit inside my mirror box when it was collapsed. I don't think mine will go on airplane though because it measures 12"x12"x12" and I think I need one dimension to be 9" like you did. I'm assuming that is the height dimension in yours. I still need to figure out how to make my aluminum poles collapse. Let me know if you come up with a good solution.

-- Craig

http://www.craigcolvin.com/Astronomy/string_scope.html

January 13, 2005 10:51 PM Forum: Telescope Making

Aluminum Class. Cassegrain truss project

Posted By Craig Colvin
A local imager built an 18" cassegrain. Here's a link to his website where he explains it.

http://www.narrowbandimaging.com/cc18_page.htm

February 8, 2005 03:58 AM Forum: Pictures of Me and My Telescope and........

Scopes Please 2

Posted By Craig Colvin
Here is the first, an 8" f6 String Scope.

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