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@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@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@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@kgXmn.com
______________________________**_________________
______________________________**_________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/**mailman/listinfo/towertalk<http://lists.contesting.com/mailman/listinfo/towertalk>
______________________________**_________________
______________________________**_________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/**mailman/listinfo/towertalk<http://lists.contesting.com/mailman/listinfo/towertalk>
______________________________**_________________
______________________________**_________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/**mailman/listinfo/towertalk<http://lists.contesting.com/mailman/listinfo/towertalk>
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|