28 replies to this topic

[George N]

I was going thru some old astronomy related papers and I found a brochure for Sky Designs Dobs that I received in the mail in 1985. They seem to have been pretty basic truss tube Dobs in 14.5, 17.5, and 20 inch sizes. While not of the quality of current premium Dobs, they look to be serviceable scope structures. The owner of this little company was a fellow named Bob Combs. Does anyone know what happened to Sky Designs? Is this brand still around? Anyone have experiences with one? Anybody want to pay me $100 for the brochure? (just kidding)

[jrcrilly]

Anyone have experiences with one?

They are heavy. Really, really heavy. I have a complete structure left over (if anyone wants to come pick it up) from a 20" F/3.8 Sky Designs that I had converted to a modern, lightweight design by Rob Teeter. They used a Dobson-style broomstick secondary holder that I didn't approve of, but the other hardware was just fine (no Dobson-style focuser or primary mounting). Decent glass, too. It worked well, but it was heavy. Really, really heavy.

[clintwhitman]

Bob is now a senior design engineer at Pulse Teck products, a military contractor

[Robert Provin]

I had a Sky Designs 18" for 18 years, purchased it in 1987. It was well made and as others have noted quite heavy. The only issue I had with mine (and this ultimately made me sell it) was the primary mirror support really wasn't up to par. The mirror that came with the scope was a Galaxy signed by Wilkinson himself, but it never performed well. In fact it was just plain bad! I came to realize that the problem was not the mirror but the support, a 9 point system that virtually always made the mirror anastigmatic. Two years ago I sold the Sky Designs structure, got an Obsession structure, put the old Galaxy mirror in it and WOW what a difference! The mirror is very sweet indeed.

Robert

[Robert Provin]

What I meant to say was the mirror always had astigmatism, not that it was anastigmatic!

Robert

[Robert Provin]

Here is a photo taken some years back of my 18" Sky Designs Dob.

Robert

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[Steve Fisher]

They also put out a 16". I know I have one with an Enterprise f/5 mirror. Big, Bulky, and not all that pretty but beautiful images.

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[Robert Provin]

Hi Steve,
The Sky Designs were pretty nice looking scopes as evidenced by your picture. Is the spider/secondary holder on your scope stock? Mine looked a bit more primitive!

Robert

[Steve Fisher]

Robert:

It probably looked a lot more like this one that I keep in the closet. Large 1" wood dowel with secondary glued to it for a secondary post. (Easy to adjust) Primitive is an understatement!

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[Steve Fisher]

I had an extra spider that I cut down to fit and built a new UCA for the scope a couple of years ago. The new one has an Astro Systems secondary and holder, Wyoroc focuser and a little bit nicer wood. It really doesn't work any better than the old one did but it looks nicer and and is easier to collimate.

I still plan to ventilate the mirror box one day with a couple of nice fans and maybe dress up the wood on the mirror box and rocker box.

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[Robert Provin]

Robert:

It probably looked a lot more like this one that I keep in the closet. Large 1" wood dowel with secondary glued to it for a secondary post. (Easy to adjust) Primitive is an understatement!

Hi Steve,
Yup, that's it. Just like the one on my old Sky Designs. Primitive and a bit crude, but it did the job! The design made it relatively simple to offset the diagonal as well.

Robert

[BHunt]

Robert,
I know you have used and built a lot of scopes in your day. What would you say was your all time favorite?
Thanks,
Bill

[Robert Provin]

Robert,
I know you have used and built a lot of scopes in your day. What would you say was your all time favorite?
Thanks,
Bill

Hi Bill,
That's a tough one! But I suppose if I could just pick one over the years, it would have to be my AP 155 EDF. For imaging and visual it delivers quite a bit in a very portable package. That said, I must admit that recently (the last two or three years) I have been using my AP 180 EDT and my 18" Obsession more often. So many telescopes, so little time!

Robert

[Joe Bergeron]

I had a 14.5" for a few years. It was at the time the biggest scope in Broome County back when Kopernik topped out at the C14. It worked okay, but was indeed clunky and primitive in many ways, not surprisingly since it was designed in a clunky and primitive era for Dobs. The Galaxy mirror (which I bought separately) was excellent. Ultimately I sold it because it was so heavy and unwieldy, at the limit of what I could handle.

[Tom Duncan]

I just picked up an 18" Sky Designs (photo below) and am in the process of gathering information and advice. Clearly there are some issues, primarily with the mirror support and collimation at both ends. It would appear the mirror is not actually held in place, it just rests on three pads (with three knobs on each) and is held laterally by 4 plastic bolts. Vertically it is contained (but not held) by 4 rotating pieces of wood off the top of the block that the plastic bolts go through. Has anyone developed/marketed a solution?

I would like to move the mirror up in the box so as to facilitate bino viewing (which is pretty much the only way I view). Any ideas on that? Anyone done it?

Also, the same question for the broom-stick secondary stalk. Seems like the adjustment screws just want to bore themselves into the wood. So does anyone make/market a solution?

Somewhere I found the information that the 18" was made in both f4.2 and f4.5 versions...any way to tell which I have? My mirror is marked only with "SD144" which I figure means the 144th Sky Designs mirror. Any idea who's mirror the company sold as the house brand?

The mirror box is carefully sealed to delay mirror cool down as long as possible. Are there preferred fans for this application?

Tom

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[jrcrilly]

It would appear the mirror is not actually held in place, it just rests on three pads (with three knobs on each) and is held laterally by 4 plastic bolts. Vertically it is contained (but not held) by 4 rotating pieces of wood off the top of the block that the plastic bolts go through. Has anyone developed/marketed a solution?

The primary cell is primitive - but the things you describe are as they need to be for it to work. You can't just clamp a big mirror like that down; it must be supported at multiple points and restrained as described. A better primary cell would still work the same way.

[clamchip]

I can't help you much with Sky Design but you might try researching Dan Arthur for the mirror.
Pick up a copy of "The Dobsonian Telescope" by Richard Barry and David Kriege (Obsession Telescopes).
You can buy it from Willmann-Bell Inc.
This book will give you everything you need and more about improving and understanding your scope.

I'm completely new to the Dobsonian and spent the last 30yrs ignoring these creations but you hit a man with a whip enough he learns to like the whip, so I'm relearning amateur astronomy Dobson style after being exposed to the wonders of large aperture by my observing mates forcing me to look through.
I'm loving every minute, greatest thing ever invented next to cutlery and the toilet.

Robert

[Gerd]

Reading in the magazin Sky & telescope in the eighties, I saw the ads of Sky Designs,
and I decided to build my 17.5 "Dob in a similar appearance.
The mirror set we ordered from Coulter spring 1987 and it lasts to January 1990 untill it was delivered.
Here some pics from the making of a 17.5 incher in Germany from 1987 to 1989......

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[Gerd]

the truss tube

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[Gerd]

Spider with secondary cage

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[Gerd]

Construction

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[Gerd]

Ready for Deep Sky observing

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[Gerd]

Today over 20 years later always in use,
one of the first homemade big Dobsonians in Germany

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[clamchip]

Nice classic Gerd. 20yrs of service, you did a fine job and it doesn't look like you needed to change anything in that time.

Robert

[Tom Duncan]

I made a simple upgrade to my Sky Designs 18" dob secondary adjustment setup by taking out the metal slot-head screws (awkward to adjust) and replacing them with 6-32 nylon thumbscrews that can be had at Home Depot (or from scopestuff). Perhaps it would have been nicer if they had been available in black but these are easier to see in the dark as white and they are not seen by the main mirror as they are behind the secondary mirror even as long as they are. This simple modification has made secondary adjustment a simple job. I will next remove the secondary mirror holder (the broomstick) and drill large diameter shallow holes to center the ends of the thumbscrews.

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