Here are some photos and text on building my 12.5 f/6
Dobsonian
This was my first effort to build a telescope or really any precise wood
working project. The first piece of business was ordering a mirror.
I ordered a Swayze 12.5" f/6 mirror. Steve's mirrors are excellent
and I'd highly recommend them to anyone. He makes mirrors from this size
to very large (30" plus).
I began in December 1999 and achieved first light in March 2000. The
process took approximately three months of sometime long hours in the evenings
and on the weekends. Below is a rough draft of some of the major
components of my Dobsonian telescope. I don't seem to have many digital photographs
of my upper cage. Please feel free to drop me an e-mail if you have
any questions or comments on this site or about telescope making. I'd be
glad to offer any help I can. After-all I learned a lot from other web
sites from ATM'ers!
Then next order of business was to design a mirror cell on cardboard (full
scale), and contract the welding work out to an experienced professional.
The result was fantastic. (click to enlarge)
Here is the mirror cell with the mirror sling installed. Note the sliced
bolt to tighten the sling? (click to enlarge)
When I place the mock mirror in the mirror cell, it all fits just like on the
drawing board! Whew! (click to enlarge)
Finally, after building my mirror box, I install the mirror cell. This
cell creates a lot of strength, and also ensures that I have a very square
mirror box. Square is essential here. (click to enlarge)
One of the most difficult part of making my Dobsonian telescope was cutting the
bearings for the sides of the mirror box. I almost burned out my
Porter-Gable router! Go slow and be accurate. No room for error
here. (click to enlarge)
Attach the bearings to the mirror box and it starts to look like a telescope for
the first time! (click to enlarge)
The sides of the rocker box have to have side arcs cut to match the
bearings. I cut the side arcs than matched the two sides up and cut the
height and width. I wasn't interested in cutting the arcs again.
The rocker box was the next task to tackle. The key here for me was making
sure that I had the two sides arcs for the bearings cut exactly the same.
Also you need to be square so you're mirror box doesn't rub when you set it
inside. (click to enlarge)
Here is the back of the rocker box. I add the small strip of the back wall
after I figure out how much clearance I need. Remember you have Teflon
sitting in the groves cut in the rocker box to hold the bearings. (click
to enlarge)
Put the mirror box inside the rocker box and you are getting closer to being
done! Check how much clearance you have in the movement. I believe I
had to take apart my rocker box to add some height so the mirror cell wouldn't
scrape. (click to enlarge)
Here is a picture of the lower truss tube connectors. Between the split of
the wood blocks, I've inserted a spring that forces the two blocks apart when
the black knobs are unscrewed. (click to enlarge)
You have to have a cover to protect the mirror. Make it circular.
Then it won't fall through the opening (tip from the Berry/Kriege, The
Dobsonian Telescope book). I've routed a lip in the bottom of my cover
to give it a nice fit and to keep it from sliding around. It works like a
charm! (click to enlarge)
Here is one of the things I really like to do when building a telescope. I
add an antique handle or piece to the "high-tech" telescope. In
this case, I added a beautiful brass drawer handle as the handle for the
cover. Nice touch. (click to enlarge)
Here is a top-view of the mirror box with the lower truss tube connectors and
bearings in place. (click to enlarge)
After all the hard work, the rocker box ground board is a piece of cake.
Remember to place the Teflon pads over the feet. The spacing of the feet
affect the stability of the telescope as well as the smoothness of the azimuth
bearing. (click to enlarge)
Here I am beside my mostly completed Dobsonian holding my unfinished upper
cage. I still need to install the focuser board, Kydex barrier, and mount
for my finder scope and Telrad. (click to enlarge)
Once the telescope is all put together, the length is tested, and the finish is
applied, and applied....and applied, you can add the other accessories. In
this picture taken at OMSI's Camp Hancock in NE Oregon's desert, you can see the
plow handles that I use to move the telescope around. I highly recommend
using pneumatic
tires. They go smoothly over any terrain!
