[TowerTalk] F12 C19XR Rivets

[Larry]

I had failure on the 240XL element to boom plate where the rivets 
elongated the holes and the element eventually fell off. Bringing down a 
2 el 40M yagi with only one element is not a lot of fun. I went to bolts 
when I put it back up only to lose it completely the next year to a 
tornado. The other element did not show any obvious signs of hole 
elongation. IIRC the element to boom rivets were done by F12.

73, Larry  W6NWS

On 3/7/2016 11:52 PM, Roger (K8RI) on TT wrote:
> Good advise Jim,
>
> My C19XR uses 3 rivets in a row at each element joint.  I understand 
> that they may have gone to 6 using two sets of 3 opposing rivets.  
> That's the way I plan on repairing the ends of the 20 m reflector.
>
> IIRC it does use larger rivets in the boom, but I don't remember the 
> size as I had forgotten the size for the elements..
> After tomorrow (63F and 55 F for a low, 59/43 and near an inch of rain 
> Wed) The snow should be gone giving me easy access, if a bit squishy, 
> to the antenna.
>
> These are what are called a "Blind Rivets" in that, unlike regular pop 
> rivets which have the mandril go all the way through, the end of the 
> rivet is solid to prevent water from leaking through, much like the 
> "Cherry Rivets" used in aircraft.  The "Sonex" little single seater 
> has all riveted joints using these "Cherry rivets" instead of the 
> typical flush rivets requiring a bucking bar.
>
> As Jim says, do not tap rivets in by taping on the mandril. Usually 
> you only forget once as the mandrel may just fall in and you no longer 
> have a blind rivet that may be a bit difficult to remove.  Trying to 
> drill out a failed rivet can be frustrating as they often just spin in 
> the hole instead of holding for the drill bit to cut metal.
>
> 73 es thanks Jim
>
> Roger (K8RI)
>
>
> On 3/7/2016 Monday 10:54 PM, Jim Thomson wrote:
>> Date: Sun, 6 Mar 2016 19:39:29 -0500
>> From: Larry <lknain at nc.rr.com>
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] F12 C19XR Rivets
>> Message-ID: <56DCCDC1.2020308 at nc.rr.com>
>> Content-Type: text/plain; charset=windows-1252; format=flowed
>>
>> In the early days C3, EF 180B, and 240 generally used 0.125 inch rivets
>> on the elements. The 180B had some 0.25 inch rivets as well if I recall.
>> Booms used 0.25 inch rivets. The C3, for example, generally had 3 rivets
>> per joint in the elements. I don't know how different the XR series is.
>>
>> 73, Larry  W6NWS
>>
>> ##  on my F-12 340N,  520, 615, EF-180B, and F12 shorty 44 foot 40m 
>> yagi, all the rivets
>> are .125, aluminum, and slightly domed heads,  with steel mandrels.  
>> The shorty 40m
>> els used longer .125” rivets on the inboard portions only, where they 
>> are triple walled.
>>
>> ##  The EF-180B  used  .1875  rivets on the else....  but only in one 
>> place.... like that huge swedge.
>> All the booms  used  .1875  rivets on the factory end  of each 
>> splice...where as the end user
>> portion of each boom splice used 1/4-20 SS  bolts  + nylocks.
>>
>> ##  No  .25  rivets were used any where.   Although those small hand 
>> riveters will pull a .1875
>> rivet, they are very tough to pull.    I bought a larger, looks like 
>> hedge shears,  type of riveter,
>> made  by pop company, aprx 25 inches  long,  to do the .1875 rivets.  
>> The same longer riveter  will also do
>> .25  rivets, and also .125 rivets.   But the big riveter is too 
>> awkward for the .125 rivets, the small hand
>> riveter is better for that job.
>>
>> ##  POP  co also makes a hand riveter, that uses  90 psi from ur 
>> compressor, to pull any size of rivet, it also
>> has an optional device to collect all the spent mandrels.
>>
>> ##  DON’T  put any anti oxidant  grease on any rivets.... only the 
>> els overlaps.   Install ALL the rivets at any
>> joint before you pull any rivets.    IE:  install 3 x rivets in a 
>> row, then pull them one at a time.   And if rivets  2+ 3
>> start to back off, after pulling the 1st one, you have to tap the 
>> rivets back in, so they are flush, b4 pulling them.
>> Tap them back in via the domed heads..and NOT the mandrels.
>>
>> Jim   VE7RF
>>      _______________________________________________
>>
>>
>>
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