[ATM] Small Dob truss question

[ntent <ntent@pctcnet.net>]

 From a welders/fabricators viewpoint, having two tubes cross in the 
same plane would require that the tubes have a flattened area where they 
cross, to more than one-half their thickness...... meaning a "flat" area 
on both sides of each tube, almost to the point where both sides of the 
tubes meet.  This can be done simply with a press of some type, and 
could probably be done for you at little to no cost at a 
welding/fabrication shop in your area.
The tubes, of course, would have to remain straight and, if bent 
slightly during the pressing, could be straightened on the same press.
I would use two bolts in the center; one left in place as a pivot (not 
necessarily in the center), and the 2nd hole would be drilled after the 
tubes have been mounted and the scope properly assembled/tested. I would 
advise the use of "shoulder bolts", which would limit how much the bolts 
can be tightened, so as to not deform the tubes upon assembly.
The amount they are pressed would indicate the length of the bolts, so I 
would have at least one bolt in hand when you get the tubes pressed. Let 
me know the tube diameter and thickness, and I can get you very close as 
to the bolt length.
If you like, I can send to a drawing (off list) to help with the design 
and the idea.

_______________________________________________
ATM mailing list http://www.atmlist.net/