[ATM] 64 pound single-pole 18" f/4.3

[Ross Sackett]

--- William Lee <wjl12 at comcast.net> wrote:

> Ross,
> 
> Was the original pole carbon fiber too? If not, have
> you noticed any  
> difference in stiffness? 

Yes, the $240 for the pole hurt a lot, but it looks
damned sexy and helped shave a pound or two from the
total weight.  Subjectively I don't notice any
difference in stiffness comparing the 2" OD 1/16" wall
aluminum tube to the 2.125 OD 1/16" wall carbon-epoxy
tube.  I am sure there is some objective difference,
but it doesn't present itself at the eyepiece.  The
weight difference is considerable when you heft the
two tubes in your hand, but overall the effect on
telescope weight is pretty minimal whether you are
building a one-pole scope or a truss since the poles
are only a few percent of the weight of the telescope.
 As I mentioned to Gil, in most cases I don't think
the carbon has much of a payoff compared to its cost
and extra work.  The next scope I build in this
general design, a 13" ruggedized suitcase portable to
take to Ecuador, will have a two-piece aluminum pole
(made from an extension handle for a concrete float,
which comes with a male threads at one and female at
the other--just saw the pole in half and screw the
ends together, and you have a two piece pole with
break-down fasteners already installed).

By the way, if you do decide to go with carbon be sure
to epoxy wood disks inside to you don't crush the tube
when you clamp it--it is surprisingly fragile to
lateral squashing.

Ross