16" Ultralight Dob
Posted 11 October 2013 - 05:22 PM
Posted 11 October 2013 - 06:37 PM
Posted 12 October 2013 - 01:47 AM
In my 10" Dob, I use 10mm U-profiles. The endpoints can rotate, so that the whole truss structure folds up for storage. I've never noticed any sag, but admittedly, never used a camera on it either...
Posted 13 October 2013 - 01:30 PM
In addition it should be remembered that ideal trusses only carry in-plane loads attached to their ends. Any other load will generate bending forces on the members. This includes torsion (mentioned by Don) and the weight of the truss members themselves. They are, after all, just beams on their own and can sag from their own weight if very long and thin