Spray the screw end of the clamp with something like liquid wrench to
reduce the friction and you will strip fewer clamps.
Doug
I'll run the race and I will never be the same again.
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Kevin Normoyle
Sent: January 28, 2010 11:22 PM
To: Tower and HF antenna construction topics.
Subject: [TowerTalk] hose clamps
an old issue, well talked about in the archives.
But after reading the archives, I thought I could be more specific.
Although people named some higher end brands before, I wanted to name
some lower end: Ideal and Breeze that I think are good. And maybe people
can respond with their specific models. There are a LOT out there, so
you have to name a model number. I'm also suggesting that the high
nickel SS 201/301 is good enough material and am interested in feedback.
I just bought and am assembling two brand new Hygain 155CA's, and I
started stripping the clamps putting them together. Was surprised,
because usually I'm pretty careful about that.
So I looked at things closely.
1) You have to thrown the Hygain clamps away. Repeat: You have to throw
them away.
2) You have to correct inconsistent Hygain-cut slots to the correct
length on all elements
3) I think the Ideal brand clamps are the most cost-effective, good
enough solution (especially because of the 1/2" requirement)
4) It's good to let it sit overnite to cycle before the final
tightening. i.e. tighten till element can just spin a little, then next
day tighten to no-spin.
5) Many hw stores have no-name brands. Visit more stores or order online
till you get the exact model you're looking for.
Basically, the clamps Hygain ships are just no good. They are no-name
brand, and the problem is the housing is too short, along with the
screw, and the housing is flat bottomed, not curved like the better hose
clamps.
People talk about stainless steel materials issues a lot, but I think
the "design" of the hose clamp is as important, if not more.
I wonder if a lot of bad experience with hose clamps, is from using
really-really-bad hose clamps.
Now people are right that marine-quality clamps are the right way to do
it. 316 stainless on the band/housing and screw.
But I wanted to keep the cost to <$1 per clamp.
The problem is the clamp needs to work on ~1/2" diameter (squeezed). The
standard minimum diameter for 1/2" band clamps, is 7/16".
I really like the Breeze brand clamps...the way their housing is
designed helps keep the max number of threads in the band.
But Ideal specs 3/8" minumum diameter for their 1/2" band clamps. And I
don't want to use two of the smaller micro clamps.
So: I think Ideal clamps are basically the right thing for cost and
no-strip capability. I've looked at the Murray Gold Seal clamps, and
didn't like the welds on the bottom, although they say it doesn't
"increase" corrosion.
On some of my elements, Hygain didn't cut the slot long enough. Using
the dremel to match the slot length to the others is required. This
happened on two elements in both antennas, so it's common. You won't be
able to clamp if the slot is too short.
Also, the Hygain directions are bad. You really don't want the clamp
housing centered over the slot. IMHO.
The Ideal clamps I got (from Home Depot because I didn't want to wait
for online order) were Ideal 67-5 series.
Specifically 6705-6. (SAE 6 size). SS 201/301 mixed in
band/housing/screw. They have a 67-6 series if you want SS 316
everywhere.
Torque 30-35 inch-lbs
http://www.idealclamps.com/catalog/clamps/detail.php?ID=10&SECTION_ID=16
They are spec'd for 3/8" to 7/8" diameter.
I think you really don't want 9/16" bands, since that decreases local
clamping force for a given torque. (these are 1/2" bands)
Grainger has the Ideal 67-4 variants SS 300 for a slightly lower end
"marine quality"
http://www.grainger.com/Grainger/items/1XHB5?cm_mmc=Google%20Base-_-Pneu
matics-_-Hose%20Clamps-_-1XHB5
Breeze clamps spec'ed here, but have 7/16" min diameter. I did have two
Breeze clamps laying around, and put those on two elements and they work
really nice, so maybe they're just as good, or better, regardless of the
7/16" spec.
http://www.normagroup.com/kunden/norma/ttw.nsf/id/EN_Power_Seal_Details
I know there are a wider variety of choices if you start going above $1
a clamp.
-kevin
AD6Z
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