Designing a telescope:
John Dobson’s mount is the basis for most amateur built scopes. But there has grown around it an entire low-cost Dobsonian style telescope.
Some characteristics of a Dobsonian telescope are:
On a small dob many people use cardboard Sonotube as the main tube.
On larger scopes a metal or wooden truss tube is often used.
Richard Berry in Build your own telescope uses a square wooden tube for his six inch dob.
My scope is a combination of the square wooden Berry tube and an aluminum truss tube, I was hoping the aluminum would reduce the weight but I can’t find weights to compare it to, Berry says that the all plywood tube weighs eighteen pounds but doesn’t say if that is just the tube or the tube plus all the equipment, if anybody has the a Sonotube or plywood tube and knows the weight I would be interested to see how it stacks up. My completed tube weighs around twenty-one and a half pounds with everything on it and seventeen and a half pounds minus the primary mirror, it’s bracket and the finderscope.
Also I wanted a tube that would be more rigid than Sonotube and more affordable the fiberglass or PVC.
For a general over view of Dobsonian construction I recommend the San Francisco sidewalk astronomers website which has a entire tutorial for building dobs 6 to 10 inches in aperture.
Also be sure to read Richard Berry’s book which is the same book as I mentioned in mirror making
