Thank God for PBS. I happened upon a show one night long ago about the
Sidewalk Astronomers. I had no idea that ordinary individuals could make
their own telescopes. I can recall the images at that time of scientists
and engineers building the Hubble telescope's mirror with large sophisticated
equipment. These were well-educated and well-funded PhD's, and they
couldn't get it right. How could I, a mere mortal, even think of attempting
such a project?
Well thanks to John Dobson, founder of the Sidewalk Astronomers, I learned
it wasn't that difficult. After watching the show, I decided to build a 6"
telescope. I called the Sidewalk Astronomers and much to my surprise and
delight I spoke to Mr. Dobson himself. We had a wonderful conversation about
how I could get started on the road to telescope building. At the time there
was very limited Internet access and hence limited info about such projects.
Mr. Dobson convinced me to start on a 10" telescope instead of a 6". He also
supplied me with book titles I might want to read as well as retailers of
telescope making supplies.
I found that "How to Make a Telescope" by Jean Texereau was my best source
of information. My first task was to grind the mirror. I bought the mirror
blanks, grinding powders and pitch material from the same retailer, although
I can't remember who it was. I made a grinding stand by filing a plastic tub
with concrete and placing a 3" threaded steel pipe in the center. After I
screwed a steel plumbing floor flange to the pipe, I attached a piece of 16"
square plywood. I put polyurethane on the wood because I knew it would get wet
from the grinding process and I didn't want the wood to delaminate. I screwed
three wood cleats to the wood platform and I was off and running. I intentionally
made the grinding stand very heavy because I wasn't sure how much force it would
take to push the tool against the mirror and I didn't want the stand to fall over.
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