[TowerTalk] securing loose element ends

[Gene Fuller]

I may be missing something here, but when I make an element, if the clamp 
doesn't quite firm up the joint I just get the hack saw out and cut another 
slot, 90 degrees around the circumfrence from the first and that allows for 
a bit more compression and preserves the potential for further length 
adjustment.
Gene / W2LU


----- Original Message ----- 
From: "Roger" <roger at rogerhalstead.com>
To: <towertalk at contesting.com>
Sent: Thursday, September 23, 2010 12:52 AM
Subject: Re: [TowerTalk] securing loose element ends


> On 9/23/2010 12:25 AM, Kevin Normoyle wrote:
>>
>>>> Hi TT'ers,
>>>> I was putting together my Hygain Ex 14 today and found something I
>>>> hadn't expected. When tightening up the hose clamps to secure the
>>>> ends of the elements (7/16") that regardless of how hard I cranked
>>>> the clamps, the tips were still loose enough that they could easily
>>>> be pulled out-maybe 10# of pressure!
>>
>> I like rivets. But I think there's a different issue here. Rivets are 
>> nice for telescoping straight tubes that fit
>> nicely within each other. And
>>
> As do I, but they will also work with properly swaged and fitted elements.
>
>> in fact I just ordered a bunch of Avex rivets from Aircraft Spruce, 
>> because I was getting too many mandrels breaking off
>> on some Pop Rivet brand rivets. I read good things about the Avex rivets, 
>> but haven't used them yet. Interestingly they
>> have a wider grip range than the Pop Rivet ones I was using.
>
> I think you will find the piece that fits into the tool (I've forgotten
> the name of it) has barbed like edges, almost like a bee's leg. These
> expand the gripping range.  "I think" (meaning I don't remember for
> sure) they are also "blind rivets" so moisture will not go through them.
>
> What rivets do other people use? I also switched to a
>> different rivet tool.
>> http://www.aircraftspruce.com/catalog/hapages/avexblindriv.php
>>
> I don't think the tool will make a great deal of difference if it fits
> correctly and works the way it's supposed to.
>
>> But the problem with Hygain, is the joints are swaged. And the swage is 
>> not that precise, so you don't get good contact
>> on hte inner surfaces.
>
> A swaged joint "can be precise", but the dies wear and they are
> expensive so manufacturers get every last mile out of them.
>>
> I've thought of trying this, but on a larger scale using rollers on
> larger tubing.  The problem with swaging or working Aluminum is the
> stuff work hardens FAST.  But at-any-rate, Those who have worked with
> lathes are probably familiar with the hand held knurling tool.  It's
> hinged at the outer end, then back in a ways are two wheels on one side
> and one on the other.  The piece to be knurled is held in and turned by
> the lathe.  The knurling tool is placed over the tube with pressure
> applied to the handles, impressing the knurl into the Aluminum surface.
>
> If the rollers were replaced with smooth rollers the tool could be used
> to compress the swaged end of the element.  Carefully done the entire
> swaged end could be smoothly compressed to fit snugly on the inner
> section. This would have to be done carefully and only a few thousandths
> at a time, but should work.  OTOH it's going to a lot of work for a
> little gain. Me? I'd think it's worth it, but it's certainly not worth
> the expense of going out and purchasing a lathe and the tools to go with
> it. <:-))
>
>
>>
>> Plus: as I noted here before, the clamps Hygain ships are no good.  They 
>> are cheapest of the cheap and will strip easily.
>> I will bet two cents there is no recognizable manufacturer name on the 
>> clamps. (look)
>>
>> So: you want better clamps, so you can get more torque without stripping. 
>> And you might want to double clamp just
>> because the swaging is bad.
>>
>> Maybe someone can comment about whether they've riveted the slit Hygain 
>> swaged ends. I would think it wouldn't work as
>> well as normal telescoping tubing.
> I've had good luck with the Hy-gain joints and connectors, but the last
> ones I used were nearly 5 years ago.  The looked a bit "tent like" made
> of SS strip, with a screw in the center.  I've never stripped one of
> those but I sure have stripped a bunch of the SS hose clamps.  I don't
> know what they use now that they've been "bought out".
>>
>
> 73
>
> Roger (K8RI)
>> -kevin
>> AD6Z
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