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Re: [ATM] Cutting the sonotube for a dobsonian
Don,
>> One variety that I fancy is using thin plywood to make a square
>> cross-section tube.
>
> Wouldn't a triangular cross-section be much stronger?
In some sense yes - it would not permit "diamond" deformation of the
cross-section. But with the square "internal" structures at three levels,
this is no practical problem, anyway.The advantage of square is when
fastening the trunnions of course, and the general simplicity.
Actually, I made a travelscope version for a 6" f/5 using the kind of
cardboard-foam plastic laminate used for signs - with reinforements at the
ends for screws. And no joining the edges!
BTW, talking of triangular cross-sections, a few days ago I had the
opportunity to see one of your focusers at close range, compliant hinges and
all. The owner was very pleased, and I can understand....
Nils Olof
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