On 11/11/20 4:00 PM, Grant Saviers wrote:
A quick look at Industrial Metal supply shows they have 0.058" wall tube
so sizes 1/8" different in od will telescope. (if not damaged)
Onlinemetals.com is also stocking 0.058 and 0.120 wall so for the
latter, 1/4" different in od will telescope.
yagimech software from DX eng can yield a good feel for the wind
strength and one can sleeve tubes once or twice (doable in yagimech) and
the strength directly adds (only true for round and square tubes).
Always lather up the overlap with Penetrox if you ever want to get tubes
apart.
Of course increasing diameter wins over more wall thickness per lb of Al.
Grant KZ1W
On 11/11/2020 15:30, jimlux wrote:
On 11/11/20 2:51 PM, john@kk9a.com wrote:
Correct , there is a lot of tolerance on extruded tubing and it will
likely
require machining to fit together.
John KK9A
Ron Gorski ron-n9au wrote:
No. The 1-1/4 inner tube will not necessarily fit inside the 1-1/2 in
tube
because of nominal manufacturing tolerances.
Ron N9AU
Have you looked at using Unistrut (actually generically called "strut
channel") it's pretty stiff, and a 10 foot length of the standard 1
5/8"x1 5/8" in galvanized steel is about $30. Aluminum is about $55.
It's kind of like erector set for adults.
There's all manner of clamps and brackets you can get for it to bolt
equipment to the struts.
There's a smaller size unistrut (low profile) which is less expensive
(about 60%)
________
Unless there's a specific need for it to look continuous, I'd just bolt
the two with a "lap joint". You don't need extreme strength - the
mounting plate under the tire will fail before the tubing will, because
of the leverage. Figure 30 mi/hr max.
(By the way, I see lots of RVs with flagpoles at the beach that are
substantially more than 20 ft)
Two bolts and two tubes overlapped.. ASCII art to follow
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If you're clever you could use one bolt, and then a couple ratchet
straps on either side of the bolt to hold it straight. Put the bolt hole
12" from the end. Stowed, it's 10 feet long, with the bolt, and the
ratchet straps holding it to wherever you're stowing it.
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Get to where you are, unfold it
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Put one ratchet strap around the pair near the end (and 2' from the end
of the other one).
Attach antenna, raise mast, done.
If the cost isn't excessive, I'd seriously look at the Unistrut - having
square sides and holes makes it easy to bolt stuff to it (rotator,
antenna) without having to use U bolts or clamps, etc.
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