RASC Calgary Centre - Telescope Making Workshops
Hosted by Phil Johnson
co-hosted by Blair Colborne and Dean Huxley
Page last updated: July 15, 2010The Telescope Making Workshops
by Dean Huxley
It all started with an innocuous question in the Spring of '95: "Hey, I'm thinking of building a telescope. Anybody else want to build one too?" Over a decade later, Phil Johnson still spends many Saturday afternoons teaching people of all ages how to build their own Dobsonian telescopes. This all happens in his basement using his tools and with material he provides. He doesn't charge any fee for this informal course - students only have to pay for the materials and be a member of the RASC. Being this friendly and gregarious has earned him the well respected nickname "Uncle Phil". (Thanks go to Rick Weis for starting this trend.)
In Phil's first class, he built a 6 inch f/8 sonotube Dobsonian which was later given to the Youth Group to use. Since then there have been many modifications and improvements. The class of 2000/2001 saw the first truss tube style Dobsonians, with 10 inch mirrors, patterned after Phil's famous blue "coffee table" scope that he had built earlier. In recent years, the design is now more minimalist and the most common primary mirror size is around 12 inches. The largest mirror is 16.5 inches. Although he hasn't totaled up how many have been built under his tutelage, we're pretty sure it's over 100. Anyone who has been to Phil's classes can see why he does it. It's rewarding to see kids and adults alike come in with perhaps no knowledge of power tools or wood working, then see them leave with telescopes they are proud of having made themselves. It's also a lot of fun!
Parts and equipment no longer needed by the Centre or its members are often incorporated into projects.
The 13.6 inch Sid Lee Telescope was rebuilt as a truss tube scope by
Phil in 2005. Among the benefits of the rebuild was a reduction of the
scope's weight from 125 pounds to 45 pounds
See Phil at General Meetings, NOVA, the Observer's Group, the Star-B-Q or the Alberta Star Party.
Costs
Phil doesn't charge any fee for this informal course - students only have to pay for the materials and be a member of the RASC.
The cost varies dramatically depending on what telescope people build. Gone are the days when everyone built the same scope for the same price. Prices on mirrors (at least the chinese ones) are cheaper every year and a 10 inch mirror set (primary and secondary) is around $400. The cost for materials that Phil provides for a 10" or 12.5" is about $150 (wood, aluminum, screws, nuts, bolts, etc.) Everyone chooses the focuser, finderscope, eyepieces, etc. they want, so it's pretty hard to nail down "typical" costs.
Contact Information
See Phil Johnson at one of our General Meetings or public star nights.
The classes start in October.
BUILDING A JOHNSONIAN-DOBSONIAN-NEWTONIAN REFLECTOR TELESCOPE
Telescope Construction A manual describing the building of a telescope in Uncle Phil's class by Nic David in a 1.2MB pdf file.
Views of the Telescopes to aid the builder! Photos by Cordell Clarke.
8" Sonatube Dobson
 Overview |
 Mirror cell |
 Tube clamp |
 Altitude bearing |
 Base mount |
 Spider and focuser |
 Focuser and Telrad |
Dean Huxley's 10" Truss Dobson
Phil Johnson's 12.5" Truss Dobson
 Overview with Phil |
 Packed for transport |
 Packed for transport |
 Truss bottom connectors |
 Truss bottom connectors |
 Mirror mount with collimators |
 Lead weight counterbalance |
 Upper cage overview |
 Upper cage & Truss top connections |
 Upper cage & Truss top connections |
 Upper cage & Truss top connections |
 Magnetic finder mount |
 Magnetic finder mount |
 Magnetic finder mount |
 Spider from top |
 Spider from bottom |
 f/6.00 |
 f/5.00 simulation |
 f/5.25 simulation |
 f/5.50 simulation |
 f/5.75 simulation |
| Cory's note regarding the "simulation pictures" in the row above. "I modified these pictures to aid myself in picking the best compromise of focal length and operator viewing height. I definitely didn't want to have to use a step ladder, yet was concerned about astral imaging. These photos helped me visualize the effect of trying different values. Having Blair in the photo showed the scope in relation to an average height male. I basically measured the original length off my monitor, did the math, and put a copy of the cage at the appropriate distance using Photoshop. In the end, I just went with Dean's suggestion of f/5, and have been completely happy since." | ||||||
Cordell Clarke's Completed 12.5" ATM
Grant Gussie's Completed 8" & 12.5" ATMs
 8" & 12.5" ATMs |
 12.5" mirror cover. |
 12.5" mirror exposed |
Phil's Fun "Minimalist" Telescopes
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Phil's Equatorial Tracker
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The Mother of ATMs
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