Garry,
When I need a lot of clamping force from a worm-drive "hose" clamp, I prefer to
use the type that secure the screw housing using four tabs/slots McMaster-Carr
calls them "Vibration-Resistant Worm-Drive Clamps". They're 100% stainless
steel (link). During assembly, to prevent galling (and then seizing), I use a
hobby syringe to inject antiseize compound into the screw housing. The last
time I used them, I fastened brackets to mount bulkhead adapters in the rotator
loop at the top of my tower:
When I assembled my "new to me" Force12 C-4XL, I determined the correct Pop
rivet to be a corrosion-resistant captive type. Again, McMaster-Carr had what I
wanted.
I've never considered using sheet metal screws in anything that needs a lot of
clamping force and/or experiences a lot of vibration.
Bryan WA7PRC
----------------------------------------------------------------------
Date: Thu, 9 May 2019 01:08:24 +0000 (UTC)
From: Garry <g.drummond@verizon.net>
To: towertalk@contesting.com
Subject: [TowerTalk] Screws used in Element Construction
Greetings all,
I am rebuilding a 17 meter beam I built about 35 years ago. At the time I used
slots and hose clamps where fastening element sections together but this time I
am going to use sheet metal screws. My tubing sizes will taper from 1.125" down
to .625" in 5 sections per side.
I can't find any information on what size screws to use unless I'm just looking
over it. I have seen a recommendation to use hex head screws rather than
typical flat blade or phillips head due to possible damage to the screw head
but nothing on screw size. I also wonder if self tapping would be a better
option than standard sheet metal type.
Any thoughts will be most appreciated.
Thanks & 73,Garry - K4OR
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