Dobsonian Mount is Complete

Where do I start with this one? How about with the punchline: my Dobsonian mount for my telescope is complete. Murphy’s Law states that as I was completing the structural components last night, it clouded over and remains so today. 🙂 Today all I did was put a few final touches of paint on it.

Thanks to Dad for letting me borrow his truck to run to Rona to pick up the plywood, and for cutting up the plywood into the needed sizes. Thanks to Jeff, too, for giving me a hand with getting the azimuth pivot hole drilled (it needed to be vertical) and cutting the v-notches on the side plates.

As for how we got here…

I bought my Sky-Watcher 8″ Newtonian telescope in 2004 from Island Eyepiece and Telescope. I’d always wanted a telescope of my own, and am quite well versed with astronomy at an amateur level. I’d come into an inheritance with the passing of my grandmother, and it seemed like a good, non-trivial use of the opportunity.

With my knowledge of astronomy, I fancied that I would want to have a proper mount for my telescope. In the range of telescopes I was looking at, there are essentially two types: German Equatorial and Dobsonian. To sum it up as succinctly as possible, the Dobsonian mount is cheaper and would have afforded me a larger telescope for the same money, but the equatorial mount has the capability to track with the motion of the sky, keeping things in view and allowing for astrophotography. So it was with the best intentions that I shunned the larger scope in favour of one that would let me do more advanced things with it.

After I got it, I found that all was not as I imagined. Yes, my back yard was dark, but it was also not landscaped, so it was a pain to set up and tear down the scope in the dark without tracking tons of sand into the basement. So I said to myself: “maybe I’ll wait until the back’s finished before dragging the scope out regularly”. Of course, the back yard was seeded the next summer, but it wasn’t ready for trooping all over it for a long while. That fall and winter I brought the scope out a few times, but each time the situation was the same: it took about a half hour to set up, then I’d view for about a half hour until I was cold, and then it would take another half hour to tear down.

What was the problem? Well, the equatorial mount and its tripod are large, heavy and need to be aligned with the north star in order to work properly. It wasn’t something that could be done while it was still light out (although I did try that) so it was fumbling in the cold and dark. When I did get to use the scope I always loved it, but the times were getting more and more spaced out. Finally, when we cleared out the house to put it on the market in the summer of 2006, I packed up the scope in its boxes, and there it remained until spring of 2008. Even with a renewed resolve to use the scope, I think it’s been out a grand total of twice since then.

My thinking on this subject has been pretty one-track: I’d use the telescope more if I had a permanent pier for it in the yard. Then I could bring the scope and mount (minus the tripod), bolt it in place and wouldn’t have to fuss. The ultimate expression of this would be building a shed with a roll-off roof as a back yard observatory. However, each time I would consider it, I would put it off. There was either something else to be done (building an actual shed, redoing stairs, etc.) or I would suffer from indecision as to where to place it with the big tree in the way, or I would shirk from the $200 that the pier adapter would cost (plus all other expenses). Also, Ian came along and he is always awake early. I couldn’t stay out late and hope for a sleep in the next day.

However, it came to a head about two weeks ago. Tammy and Miranda were going through a flyer for edutainment toys and such and Miranda was putting stickers on things she’d like for Christmas, and one of those things was… a telescope. She’s really developing in such wonderful ways and that thrilled me, but it also sorta twisted the knife a little deeper. Miranda is too small to even use the scope easily: the equatorial mount always seems to put the eyepiece at the oddest angles, and she certainly wouldn’t be able to move it around: I have trouble finding the axis locking levers myself at times. So there’s me with a fine amateur scope, sitting unused, with a daughter professing interest in a telescope.

I started looking at little scopes. There’s a kind from Tasco that a kid can cradle in their lap, even. But I would always drift back to my problem with my own scope.

And then it hit me. Why not buy a Dobsonian mount for my scope? The telescope is just a tube that can be removed from the equatorial mount. Why not buy a cheap Dobsonian mount for casual viewing? Maybe to others that would have been a bleedingly obvious solution, but it only occurred to me last weekend. A call to Island Eyepiece dashed my hopes somewhat: they could only order a Dobsonian mount for 10 inch scopes or larger. Mine’s 8 inches. So it was pay $110+ for an ill-fitting mount, or look online for some construction plans.

For those who are not familiar with Dobsonian telescopes (and didn’t follow the Wikipedia link above), John Dobson was a character who in the 1970’s designed a type of telescope that was effective, and yet easily built from scrap materials that might be lying around. He would build the telescopes and set them up on the sidewalk, inviting passersby to look at the Moon, or Saturn, or other sights. His invention was one of the main reasons that amateur astronomy has undergone such a revival in the last 30 years.

I found the plans I needed here. The rest unfolded over the space of about a week. I learned a lot during that time; I’m not much of a woodworker but the design is simple enough. When I showed the complete telescope to Miranda, she could push it around, and the eyepiece is just slightly above her eye level at the moment, so a small footstool will be needed but that’s just for the short term.

Now I’m starting to think that building another might be fun. Anybody know where I can find a copy of The Dobsonian Telescope, A Practical Manual for Building Large Aperture Telescopes?