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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