dobsonian mount for 300PDS ?
Posted 09 October 2013 - 12:45 AM
Maybe anyone has already done to building dobsonian mount for sky-watcher 300pds OTA (12") ?
thinking about buil;ding that dob for these OTA.
think, plywood is a good material for that, but maybe anyone can say, what thickness is optiimal? 18 - 21 mm ?
i be happy for any suggestions and advices.
Posted 09 October 2013 - 05:26 PM
Posted 10 October 2013 - 12:44 AM
looking also on some russian and english projects, and think as alt bearing try use a rollers wheels.
15 mm plywood not too thin \ flimsy?
i thinking about 18mm laminated from both sides. think a regulate alt friction like on a serial "skywatcher" dobs - via tighten construction and add friction via that...
sorry for my bad english...
Posted 11 October 2013 - 10:20 AM
alt bearing diam 360mm
clearance between side parts: 400mm
thickness of plywood: 15mm (you can see that i stiffend the open end of the box with 20mm square pipe)
distance between ground board and center of alt bearing: 680mm, that gives you a clearance of 170mm between scope and ground board.
Posted 11 October 2013 - 01:21 PM
i see, you not using azimuth bearing at all? what observations can possible without az axis? :-O
and why groundboard is 50x50 cm, if clearance between walls is only 40 cm?
Posted 12 October 2013 - 04:43 AM
the az-bearing is a turntable unit.
You want to build a nice looking one: