Getting Started In My First Project

Hi Guys,

I’m in need of some suggestions. I’m currently thinking of making an 8 Dobsonian. I currently have a 15” Obsession (I really love this scope) and an Orion 8 XT. The Orion 8 XT is a pretty good scope with exception of the mount. I tried different laminates and every trick to get it smooth but after using the Obsession, well I decided to start over from scratch with the 8 inch.

I’m thinking of using the optics out of the 8-inch and making it a truss system. I’ve seen several designs and I really like the idea of a collapsible truss. My main goal is to make this scope lighter than the original 42 lbs and more portable & easier to handle for quick setups. Do any of you know of a good book or info that can get me started with design concepts? I have Dave Kriege book on making large aperture telescopes.

Also, while it's on my mind. Can anyone suggest good CAD software that doesn’t cost $700.00? I’m trying to make a Cadillac on a budget.

Thanks Guys
David Pope

In the appendix of the Kreige book is an excellent design for and 8" f/6 dob, exactly what you have. A truss is great if you really need a compact design for storage/transport considerations, but they are somewhat more difficult to execute. I have made two using the Kreige design in the appendix. The total weight was about 18 lbs for the ota and about 30 lbs for the rocker box and groundboard combined, maybe a little less. The nice thing about using a tube is that it is very easy to make it to rotate, keeping the eyepiece always at a perfect position. I was able to do all my observing with thr 8" f/6 while seated in a regular chair while the scope was on an equatorial platform.

Walt