[TowerTalk] split collars

[FireBrick]

I think what you are referring to are scaffold clamps.
We use them in those big pipe scaffolds that masons/workers use in building
construction.

Basically they are two/hinged/ clamps.
Each of these hinged clamps goes around a pipe and the two clamps are
connected.
Each clamp has it's own bolt/nut that is on a swivel and slides in between a
slot on the other side.
Tighten down on that nut and they really grab.
The clamps come in three basic types.
The parallel pipes configuration,
The 90 degrees configuration,
and
The swivel to allow for all sorts of angles.

The clamps also come in various sizes from 1 1/2 up to 2 1/2 diameters.

I use these clamps as gin pole connections.

Now here is the problem. They aren't cheap but can be bought at a
scaffolding sales/rental business.
If your in a big city, it will be easy to find.
A major vender of scaffolding is Patton Scaffolding
http://www.sfiec.com/show.asp?url=http://www.sfiec.com/PD-OSTEELPIPESCAFFOLD.htm

has a picture of this type of clamp.

And as for the holding the mast above the bearing question.
I've been using mine for this for years.

BTW: Make sure you don't drop one of these on the ground crew, they are
HEAVY duty.
Be Safe: wear Hard Hats.

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My family tree needs to produce more wood and less nuts.
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W9OL, Bill H. in Chicagoland