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[TowerTalk] drilling chromoly es similar pipe

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Subject: [TowerTalk] drilling chromoly es similar pipe
From: (
Date: Tue, 1 Jul 1997 07:30:26 -0400
Yeah, I saw that.  I dont care for the idea of using rubber in a mast
clamp.  I doubt it will hold very least around here.
Rubber is not a particularly long-lived product.  Also, if you do that and
add it to the cradle (in addition to the clamp), you'll throw the mast off
center.  My goal is and always will be to install something to last for as
long a period as possible without requiring maintenance, and that sounds
like high maintenance to me.  I still say that if you have the clamp
tightened properly and add the through bolt, you are not going to have any
problems as long as you havent overloaded your rotator.  (If  you have a
Yaesu rotator, all bets are off!)  It's also important to pay attention to
dynamic balancing, which will go a long way to keep things from spinning in
the first place.  Then if you still have problems, maybe it's time for a 3
inch mast!

I think if you have a tight clamp, with a hardened thru bolt in a chromoly
mast and you shear something, you've got a design problem.

73, Tyler K3MM

To:   Tyler G Stewart/BENN/CEC
Subject:  Re: [TowerTalk] drilling chromoly es similar pipe

Agreed about the bolt...but...most people believe (wrongly) that everything
will stay the same.  When you have wind, rain, sleet, snow, and various
other forms of weather above the roof line or tree line, something is
stressed.  If you use a bolt through a hole in the mast...the bolt or the
mast WILL give.  I understand that the bolt is not meant to take ALL the
torque, but people rely on them way to much.  I have seen bolts break and
holes wallow out.  Just a hugh expense and an accident waiting to happen.
Never...NEVER....drill a hole in a mast.  It is not worth it.  The rotation
of the beam will severelt over tax the bolt and the mast over time.
Guranteed.  K7LXC came up with a neat idea I had never heard of..and that
to wrap the mast that goes into the rotor with some rubber and tighten the
rotor down.  I could see that gripping better than metal on metal.  Never
used the technique...but plan to shortly.
Of course...this is IMHO.

At 04:59 PM 6/30/97 -0400, you wrote:
>The bolt thru the mast isnt meant to take all the torque.  It's only there
>for insurance.  In case the clamp slips, it's not going to rip out coaxs
>and things like that.  It should, however, assist the clamp in some small
>amount...just dont rely on it exclusively.
>73, Tyler K3MM
> on 06/30/97 12:21:10 PM
>cc: (bcc: Tyler G Stewart/BENN/CEC)
>Subject:  Re: [TowerTalk] drilling chromoly es similar pipe
>At 01:15 AM 6/30/97 -0500, you wrote:
>>i am doing some antenna repair and part of the repair requires drilling
>>heavy mast.  by heavy i mean 1/2" wall thickness chromoly steel.  after
>>burning up several bits and a few $$$ let me pass this tip:  use a
>>masonry bit ( carbide tip ), lowest speed on drill press, and lot of
>>oil.  the most expensive bit i have used only did about 1/8 inch deep
>>( cost about $12 ) and the least expensive was the carbide tip masonry
>>type.  it has taken me over 4 hours of drilling to make a 5/8 hole in
>>some of this stuff but i am betting it wont bend!
>>put em up high and hope they stay up!
>>73, de bud
>Opinion:  I don't like any holes in my mast.  Now, I have never use
>Chrome-Molley masts and I know they are hard, but I have used steel masts.
>I have drilled holes to connect masts together..etc..etc...and the holes
>wallow out over a period of time.  The beam then really moves in the wind
>and damages the rotor.  I have tried all sorts of schemes to stop this
>happening...using shoulder bolts, heating the metal and pressing on the
>bolts, etc...etc.  It will wallow out.  The best solution is
>never..NEVER...drill a hole in a mast.
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