Since publishing an overview of my new 16" Dob "Merope" on the pinned "Post your home made scope" thread, I've had many PM's asking for more construction details. So this thread is my reply to you all. Feel free to join in sharing your own ideas and pictures.
First some background.
Merope arose from a decision to build a portable 16" f/4.5 binoscope "Sterope" constructed with marine plywood. As arrival of my mirrors would be staggered by a year, and my order for marine plywood was stuck somewhere overseas (unbelievably it was specially imported from Europe), I decided to first build an interim "quick and dirty" telescope using a cheaper construction grade ply to test and experiment with techniques and engineering ideas I was thinking of using on the bino-scope, and hopefully get it finished by Christmas to enjoy with my kids.
Of course, it didn't get finished by Christmas, and Merope soon went from being "quick and dirty" to being a no compromise exercise in engineering and finish. Well...there is no such thing as no compromise, so I've described it a low compromise. And naturally I had my own constraints. Below is a quick over view of the "musts" and "desirables" and "constraints" as I recall them, I'm sure many of them are common to us all...
Design Drivers (in no particular order):-
1. Must be portable. Must unpack and fit in boot of an ordinary sedan for long distance trips.
2. Must utilise wheels and be easy to move around home with minimal or no lifting.
3. Must be easily hoisted onto back of a utility truck for quick local trips without dismantling.
4. Must be stiff. Parts must not wobble, flop, twist, bounce or flex. Must maintain good collimation.
5. Must tolerate a wide range of eyepieces up to TVNag'31+PC without rebalancing.
6. Must be buttery smooth to operate
7. Must look good and be practical. Form should follow function. Engineering should be elegant.
8. Must be solid and robust, not flimsy or fragile
9. Must be a pleasure to use
a. should have setting circles for faint objects
b. should protect mirror from insects and spiders while not in use and stored in garage or verandah
c. optics should normally stay in the telescope and be mechanically protected to reduce risk of damage
d. should be inherently flexible, easily modified and capable of new attachments and later additions
e. trusses should fold flat and stay together as a single assembly
f. eyepieces should be accessible from the ground - mirror should be set as low as possible
g. should avoid anything electrical - no wires or soldered joints, no motors, switches or encoders. A fan may be an exception.
h. should be reasonably lightweight and capable of being handled by one person
i. should not use tools and/or loose parts for setting up, should utilise hand operated latches and fixtures
k. should not require extensions for eyepieces, focuser should have enough travel for occasional camera and eyepieces
i. I only have tools for working timber, and cutting aluminium, steel and plastic. Any turning, milling or welding would have to be paid for.
ii. I have no experience or equipment for resin based composite materials (carbon fiber, fiberglass etc)
Most of the above first applied to my binoscope plans and were carried over to Merope. However after completing Merope I realised I had another essential requirement;
10. MUST be able to be wheeled into the house and fit through an ordinary door (and the pool fence gate).
Although at 700mm wide Merope met this condition nicely, there was no way my larger binoscope design would, so I've had to abandon my early Bino-Scope designs that influenced Merope and start again...but that's another story.
Edited by Oberon, 05 February 2015 - 09:32 AM.