[TowerTalk] F12 C19XR Rivets

[Roger (K8RI) on TT]

Al doesn't rust but it easily corrodes like crazy. See water in coax.  
Anodized Al is corrosion resistant, but still subject to abrasion from 
particles from the road and that abraded part is subject to corrosion.  
Just look at the surface change of the bright and shiny. Generally a 
glue, or epoxy can be removed by heating no where near the point of 
changing the temper.

As to engineers, I retired as project manager, riding herd on teams. 
There is a fine line between focused and tunnel vision. Engineers 
generally start with the details and work up.  Project managers 
generally start with a holistic (overall) view and work down to the 
details.  I've heard riding herd on Engineers compared to herding cats,

As to just following the MFG directions...
Although Antennas should be a mature science, many commercial antennas 
do have weaknesses, whether mechanical, electrical, or both. Antenna 
manufacturers for the mass market have the same constraints any other 
business.  They must make a profit in a competitive field.  That means 
the mechanics/Mechanical engineers must take into account of every part 
and engineer the antenna in a manner to keep costs down, So the end 
result may need a bit of work.

As I've said before, we know Riveting, screws, cross bolts, and split 
ends with hose clamps work.  Each has strengths, but like split ends are 
often misapplied.  Use the proper size hose clamp for the size of tube, 
they are very effective, if rather crude looking.  Rivetind and screws 
near the end of the outer tube introduce weaknesses and with the element 
ends, it doesn't take much.  Hy-Gain antennas were losing tips, or 
making noise. A poly rope dampener inserted into the element ends and 
held bu the end cap was very effective in reducing, or eliminating the 
problem

The point is that many antennas fir the mass market  a oroblem or two

73

Roger  (K8RI)

On 3/12/2016 Saturday 12:56 PM, Jim Thomson wrote:
> 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
>


-- 

73

Roger (K8RI)


---
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus