[TowerTalk] Homebrew Crank-up
jimlux
jimlux at earthlink.net
Sat Mar 27 16:34:53 PDT 2010
Stan Stockton wrote:
> As mentioned the lower section would be large (33 inch face) tower
> with 3 inch diameter legs. The top would either be 55G or 65G. I'm
> interested in ideas for rollers, etc. Not worried about whether it
> will stay up or not. There would be guy wires on lower section.
>
> Stan, K5GO
>
>
So the inside "diameter" of the lower section is about 27-30 inches?
That's quite a bit larger than the outside dimensions of the 55G or 65G.
You'll need to fabricate some sort of traveler that would hold the
"bottom" of your upper stick. Having a lot of clearance does mean that
"binding" might be less of a problem.
I'd think about something that is a few feet tall with rollers at the
top and bottom. That way it would stay properly oriented laterally.
maybe roller pairs at an angle, to provide torsional stability of the
traveler.
Something similar at the top of the lower stick to serve as guides for
the upper stick as it emerges. Here, I'm thinking 3 pairs of rollers (a
pair at each corner).
You need to do a little calculation and see how much bending moment
there is on the upper stick, so you know what the lateral force on those
rollers is going to be.
You might be able to not use rollers at all on the top.. just have a
metal sliding on metal sort of thing, although I'd worry about wearing
off the galvanizing.
You're defininately going to have to be able to climb the outside of the
outer section, because whatever is at the top is going to need
maintenance (e.g. greasing of the bearings)
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