First a little about me . When I was about 6 years old my Dad had an 8’’ wooden tube reflector on an equatorial mount. I wish I could say that I was hooked for ever. But the novelty was short lived and I didn’t give it much thought for the next 38years. Then I met Gary, who was doing some interesting stuff with a small CCD camera and an ETX90, and the flame was rekindled. It was not long before I bought my first telescope. After extensive research I decided that aperture was almost every thing and picked a 6” Meade Starfinder. I also got sucked in by the eyepiece sale and bought two of the worst eye pieces !! The good part is all the wonderful things I’ve seen since then.

One night in the fall of 1999 Gary and I were dreaming about a larger aperture, and the subject of construction came up. I am a mechanically inclined person and must have shown some enthusiasm, because Gary came up with a “you build I’ll buy” proposition. We decided to do some more research and give it some more thought.

Gary got on line looking for information and I went to the local telescope store (Captain’s Lynwood WA.) I picked up a book written by David Kriege & Richard Berry called The Dobsonian Telescope. Once I picked up this book I could not put it down. I read through it the first time and knew I could build a good scope. Over the next few weeks Gary and I talked many times and decide that a 20” Dobsonian was the largest telescope that we could transport easily. Gary wrote a check and the construction began.

While reading “The Book” again several times I made parts list for all the hardware. The real work of finding vendors began. This when I made my first of many compromises to come. I was unable to find 5/8” Appleply plywood and decided that with a few adjustments 3/4” plywood would not change the weight of the secondary cage. I also purchased some solid Maple to make the clamp blocks with. Several more vendors and I was ready to start construction.

After making a circle cutting attachment for my router and checking and double checking the layout it was time to start cutting the Appleply. Despite my case of nerves the rings came out fine. The basic structure went very nice but to get an accurate weight of the complete secondary Gary and I had to decide on the optical hardware.We placed an order with Nova Optical System for a 20”f-5 main mirror and a 3.50” diagonal mirror . We also tracked down a 2” crayford focuser , a Telrad reflex site and a laser collimator at Anacortes Telescope and wild bird. We also ordered a spider with a diagonal mirror holder online somewhere? With every thing assemble I was very happy with a 12lb secondary cage.

The next step was to build the mirror cell. I was able to fabricate most of it in a home made jig. I also decided to add a little weigh and support by using a 27 point flotation system instead of a 19 point system. The cutting of the stainless steel triangles I laid out and contracted out there cutting. The final tailgate assembly is finished with hand made maple collimation knobs.

Building the mirror box is the toughest part yet. With help from Marty (one of my wonderful neighbors) and his table saw, our beautiful sheets of Appleply were being transformed into a telescope.The tailgate fit good and we are ready for a main mirror.
I also laminated some Appleply using a Ford Explorer wood press to build a set of bearings and a dust cover. Necessity being the mother of invention I built a machine to finish the bearing surface. The bearings are removable for future changes.Again everything went very nice with the mirrorbox assembly.

The construction of the clamp blocks and the strut clamp was a real adventure.Again a friend (Lance) helped me with the machining of the rough cut maple into finished boards. The strut clamps ended being made from Appleply after procedural mistake with the maple board. The clamp blocks ended up a little different than planed. But both look okay and can be redone later if needed.

At this point I am still waiting for a main mirror. When the mirror arrives the actual focal length can be determined and with that the final balance and mirrorbox length. Then construction can continue.

Yahoo!! We almost have a mirror the folks at Nova sent the certificate and gave us a discount without any urging. As soon as they recieve the final payment the mirror will be send off to be coated and soon construction will continue. The Ronchigram looks better in person and We think it is a high quality mirror

With the mirror here the project advanced very well. With The actual focal length determined thesecondary can be finished and the truss tube angles set. All the hardware was installed on the secondary for final weight and balance.

The bearings and the rocker box required more laminating. We also purchased a Tech2000 drive system to automate the telescope. After the truss assembly was finished the balance was tested and three inches were removed from the bottom of the mirror box.

We decided that having a battery in the mirror box was not going to work. I set some copper rings in the ground board that will ride on a set of brushes in the mirrorbox. That way a larger battery can be outside the telescope. I also mounted the the handles for transporting.three inches were removed from the bottom of the mirror box.

There are several extra circuit installed for future advancements. We have switches for main power the drive the mirror cooling fan and three extras for ccd power, dew heaters and one extra? I also redesigned the the azimuth drive so the drive motor moves instead of tilting the mirror box. The altitude drive is also in the middle of a redesign.

webmasterMikeLast update at 11-5-2002