See below.
Stan
Sent from Stan's IPhone
> On Aug 13, 2015, at 10:21 AM, Michael Tope <W4EF@ca.rr.com> wrote:
>
> Stan,
>
> A couple of questions:
>
> 1) Does the counterbore go all the way through the one wall of the outer
> diameter piece?
Yes
>
> 2) Is the clearance between the counterbore diameter and the cap screw head
> diameter critical?
Not very critical but you don't want a huge hole for the head of a #8 socket
head cap screw. Just enough so it passes by the OD on the side where you
insert it. The drill bits do a perfect job.
>
> Thanks,
>
> Mike W4EF................
>
>> On 8/13/2015 6:53 AM, Stan Stockton wrote:
>> After about 40 years of making my own antennas I learned something a few
>> years ago when faced with assembling 65 tribanders (520 elements) we made
>> for WRTC2014.
>>
>> I was introduced to the element joint attachment method I am told is used by
>> Optibeam. I was skeptical when I heard the verbal description, having
>> settled on pop rivets after every other conceivable method about 20 years
>> ago.
>>
>> I made one element with pop rivets and another with a single stainless steel
>> socket head cap screw with a counterbore (head clearance on socket head
>> screw) for one wall of the larger diameter tubing for each joint, then
>> grabbed each one in the center and violently shook them back and forth. The
>> one with SHCS joints felt like one solid piece of tubing as compared to the
>> pop riveted one.
>>
>> It is so easy and so solid, I will never mess with pop rivets again.
>>
>> A V block fixture with stops, drill press and some of these bits along with
>> straight bits for the smaller diameter tube drilling are all that is needed.
>>
>> http://www.wttool.com/index/page/category/category_id/14686/
>>
>> make the job easy in comparison to many methods. The counterbore is
>> important. Use stainless nylock nuts.
>>
>> YMMV but I'm sold on it.
>>
>> 73...Stan, K5GO
>>
>> Sent from Stan's IPhone
>
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