[TowerTalk] F12 C19XR Rivets

[Jim Thomson]

Date: Sat, 12 Mar 2016 10:53:02 -0600
From: Kevin Stover <kevin.stover at mediacombb.net>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] F12 C19XR Rivets

###  back in the mid 80s...Alcan here in canada, devised a method to weld aluminum...
as in super thin stuff.....including aluminum foil used by your wife in the kitchen.
The idea at time was to   use the new process.... for aluminum car bodies.
Obviously u wouldn’t want to pop rivet cars bodies together.   They had it all 
down to a fine art.   When US steel  found out about the proposed aluminum
car body manufacturing method, they went beserko, and the politicians 
quickly finished off the  idea....never to be mentioned again.   Rust
doesnt sleep..and aluminum doesn’t rust. 

##  On a side note,   I asked the local mobile aluminum welding guy here in town
about coming here to weld some thicker wall  boom material and other items for me,
like channel al  etc.   He told me that IF  you don’t require any kind of electrical connection,
a special kind of glue can be used.... that is one helluva lot strong than any welding process.
‘Only god can get it apart’  he tells me.   They now glue  motor bike frames  with it..and also bicycle
frames etc.   It works too,  but  no electrical connection, and it cant be taken apart, has to
be cut off.   Ironicly, its being used on exotic al car bodies. 

##    On my f12  40m boom, they weld every 120 degs.... where the boom drops  from
3 inch od...down to 2.5 inch OD.    A short length  of  2.5 inch OD is sid over the end of the
2.5 inch tube.... then  welded every 120 degs.     So u end up with a stepped reduction,
and the boom drops from 3 inch  to 2.5 inch.   No taper used.   Then  1/4-20  SS bolts
and  SS nylocks used to bolts the 3 inch and 2.5 inch booms  together.   Where the bolts
pass through.... it’s a total of .375 inch thick material. 

##  Somebody actually makes  tapered   aluminum tubing.  I saw it on the other side of town,
used for marine applications.   Perfect taper from 2 inch...down to .5 inch......and overall  length 
was aprx 20 ft.   Then a  2nd  tapered  piece, but bigger OD   at each end, was used to splice
to  smaller stuff.   So the entire  marine vertical was  just 2 pieces.   So it can be done. 
They can also taper  the wall thickness..from  thicker at the big end..to thinner at the smaller  OD end. 
Dunno who makes it nor the process used. 

Jim   VE7RF 





Someone would surely have to do a full on metallurgical analysis to be 
happy with the resulting Yagi.

I have read every post of this discussion (God help me) and have noticed 
a couple things.
Some of the folks in this discussion really, really, need to get a hobby.
My uncle, a former Collins engineer with an EE PhD told me once that the 
first class all prospective engineers should be required to take is when 
to and when not to "engineer".

I may be wrong but I thought I saw a recommendation to weld the tubing 
joints?
I'd be willing to say the vast majority of members on this list, with a 
few exceptions to be sure, have neither the necessary skill or equipment 
to pull that off without blowing big holes in the aluminum and spending 
a lot of money fixing stuff they "created". If done correctly it would 
result in a joint that will never come apart, ever.

Just build the antenna the way the manufacturer intended and enjoy using 
it, simple.


  I guess if one really wanted to be picky, the ultimate solution would 
be to invent a device that could extrude tubing on site with a built-in 
taper.
No joints! You could build your yagis the same way eavestroughers 
manufacture seamless gutters on site. With enough adjust ability to the 
extruder, you could even manufacture one-piece booms.

73, Kelly, ve4xt

PS: the on-site extruder was a joke. Please, no comments on whether the 
metallurgy is sound! Sent from my iPad

-- 
R. Kevin Stover
AC0H
ARRL
FISTS #11993
SKCC #215
NAQCC #3441