[TowerTalk] Screws used in Element Construction

[Billy Cox]

Good Afternoon All,

What Bryan is describing here is a SAE J1508 Type F HD clamp 
that uses a "staked" clamp design, which uses a two-piece housing 
is staked at each of the four corners.

The true HD versions use a 5/8" bandwidth, which is wider and
also thicker, a longer housing of thicker material. They also do
not come is sizes as small at the normal Type F in the 1/2" and 
9/16" bandwidths. So this is not a 100% solution for all sizes.

Beware as there are clamps out there by Breeze/Norma and at one 
time by Norton (now a SK company) that have the same "look" but 
use a thinner knock-off staked housing, but are not as strong
as the Type F HD which is actually as strong a a t-bolt clamp. 

A normal SAE J1508 Type F clamp has an ultimate (DO NOT EXCEED)
torque of ~50-60 inch-pounds. The Type F HD (5/8" band, staked 
housing, etc.) has a ultimate torque of ~ 150 inch-pounds.

Suggested installation torque is 50-70% of the ultimate torque.

That's is why Bryan has better results with the Type F HD" than 
the normal or standard "hose clamp" found in most places.

Hope that helps!

73 de Billy, AA4NU

Former Product Manager for Ideal Clamp Products


> On May 9, 2019 at 12:18 PM Bryan Swadener via TowerTalk <towertalk at contesting.com> wrote:
> 
> 
>  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 at verizon.net>
> To: towertalk at 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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