Jerry,
What's the yield strength as specified from the mill? That's the
important number. You will loose about 20% in yield strength due to
galvanizing. You'll also gain about .010 in O.D. if the galvanizer meets
the
ASTM specs. That 10 thousandths of an inch could hurt you if you are
not careful. It'll cost you another $100 or so also. I doubt that it's
worth it to
galvanize it. See below.
As far as painting it, I wouldn't go to that much trouble. Just sand it,
spray it with zinc chromate
(outside and as far in as you can) and a coating of Brite Zinc (or other
good cold galv spray) on top of the zinc chromate. Check my Website for the
product distributors I used.
http://www.erols.com/n3rr
Once it's been treated as above, if any rust appears it won't eat it too
far. The
Chrome moly is quite resistant and will tend to form surface rust only.
I have a 19 foot Chrome moly 2" O.D x 3/16 in tk (120,000 # yield strength)
mast supporting
an EF 180C and a 155CA with 3 feet inside the tower and 16 feet
out of the tower from @ 134 ft. - 150 ft. Lots of pics on my Website.
73,
Bill, N3RR
----- Original Message -----
From: J. Kincade <w5kp@swbell.net>
To: <towertalk@contesting.com>
Sent: Friday, June 29, 2001 2:26 AM
Subject: [TowerTalk] The mast is here
> Guess I'll have to take back the poormouthing I did about my local tubing
> supplier. He delivered a 2" x 23' piece of 3/16" wall 4130N Chrome moly
> today for $125 including shipping from Chicago and tax. I was impressed.
It
> is truly incredible how stiff this stuff is for its relatively light
weight.
> It's not galvanized, of course, so now I have to investigate the
> possibilities of doing that, but worst case is I have to clean it and
paint
> it inside and out. I hope I don't regret not going for the 1/4" wall,
which
> I could have had for about $7 per foot, but at a considerable penalty in
> weight. I had to take pot luck on any length available between 19' and
26',
> so am of course happy with the 23'. This will leave me with 13' inside the
> 45G, and about 10' sticking out (antennas at 1' and 5'), pretty much
> negating any major worries about sideways rotor stress. All I have to
worry
> about now is will the 3/16" 4130N handle the load, and I'm pretty sure it
> will. The extra 2 feet above the 75M dipole truss is for who knows what
some
> day.
> Jerry W5KP
>
>
>
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List Sponsor: Are you thinking about installing a tower this summer? Call us
for information on our fabulous Trylon Titan self-supporting towers - up to
96-feet for less than $2000! at 888-833-3104 <A
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