[TowerTalk] A quest about Gin Poles

[Patrick Greenlee]

Don, My specific application was an "A" frame (two gin poles) and my 
friend's concern was letting either leg get "out of column", a malady most 
observed near the center of the poles.  I welded my poll extensions onto 
both ends of the two legs and am living happily ever after.  The triangular 
tower this was for is 14 feet (not inches) from leg to leg at ground level. 
It is 4 1/2 inch OD steel tube legs in 20 ft sections with 1/4 inch wall 
thickness.  Two legs are hinged for tilt over. This tower was 100 ft tall 
with no guys.

Patrick AF5CK

-----Original Message----- 
From: Don Moman VE6JY
Sent: Thursday, May 30, 2013 4:36 PM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] A quest about Gin Poles

The greatest bending moment is at the bottom of the gin pole where it
attaches to the tower, not in the center.

On Thu, May 30, 2013 at 9:30 PM, Patrick Greenlee
<patrick_g at windstream.net>wrote:

> A good friend who has MS in mech engineering and 35+ years of hands on
> experience made the following suggestion to me:
>
> Do not splice the pole in the center where the greatest bending moment is.
> Add the extra material near the ends.  In your case that would require you
> to cut one of your poles in half and add the pieces on either end of the
> uncut pole.  If able, you may want to consider making the connecting piece
> fit over your poles rather than inside. That would be significantly
> stronger.
>
> Just food for thought. YMMV
>
> Patrick AF5CK
>
> -----Original Message----- From: K8RI
> Sent: Thursday, May 30, 2013 4:13 PM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] A quest about Gin Poles
>
>
> On 5/30/2013 4:50 PM, Kevin Elliott wrote:
>
>> I have purchased all of the item to build my gin pole but I have one
>> question I am hoping someone can answer.  I have two seven foot pieces of
>> 2" x .250"
>>
> aluminum that I am going to use for the gin pole itself.  I also have a
> 6' length of 1.750" aluminum that I am going to use for the connector
> for the two 7' pieces.
>  Now my question is this; how long should the 1.750" piece of aluminum
> be for the slice of the 2" pieces?  I think having 3' in each of the 2"
> pieces is
> overkill and will add weight to the device. I was thinking more along
> the line of 4' section which allows 2' in each of the sections. Or
> should I go with 3' on each piece?
>
>>
>>
>>
> Having worked with these things for years, I wouldn't use a 2 piece gin
> pole except for very light work.  2nd I would consider the smaller
> inside splice to be too short.  The first question is what alloy and
> temper is the tubing and splice?
>
> I use 12' and 24' sections of 6061T6 with 1/8th, 3/16 and 1/4 inch wall
> depending on the load.
>
> I would ask an engineer about the configuration you are planning.
>
> Climbing and using gin poles in tower work is quite dangerous!
> Every year we lose a number of well trained and experienced climbers.
> When something breaks up there your only thought is to get out of the
> way with out getting off the tower.
>
> Working on a 40 or 50 foot tower can be just as dangerous as working on
> the big ones. You are just working with smaller stuff which can be just
> as deadly as can a fall from that height.
>
> Be careful
>
> 73
>
> Roger (K8RI)
>
>
>  Thanks
>> Kevin Elliott
>> KGXMN
>> kgXmn at kgXmn.com
>>
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