[TowerTalk] 2 inch Chrome Moly mast needed

[john at kk9a.com]

My suggestion was to consider a 3" x 1/4 wall 1026 instead of a 2" Chrome
Moly mast. I suspect that 3" 1026 is stronger than 2" 4130 (I don't have a
mast calculator handy) and it is easier to climb. I purchased a 3" 1026 DOM
from steel company and had it galvanized.  My costs were significantly less
Array Solutions plus did not want their odd 2 7/8 size.  At that time DX
Engineering did not sell masts and no one else sold a 3" mast so making one
was my only option. 

John KK9A


To:	<towertalk at contesting.com>
Subject:	[TowerTalk] 2 inch Chrome Moly mast needed
From:	"Jim Thomson" <jim.thom at telus.net>
Date:	Thu, 7 Apr 2016 14:59:51 -0700
List-post:	<towertalk at contesting.com">mailto:towertalk at contesting.com>
Date: Thu, 7 Apr 2016 06:34:30 -0400
From: "john at kk9a.com" <john at kk9a.com>
To: towertalk at contesting.com
Subject: Re: [TowerTalk] 2 inch Chrome Moly mast needed

If you really need that much strength, consider a 3" 1026 DOM mast. Your
tower is not made of chrome moly why does your mast need to be? I cannot
imagine why 2" is the standard. Do you really want to climb 15 feet of 2"
tubing?

John KK9A

##  2 inch OD  x .375 chromolly tubing weighs the same as 3 inch OD x .25
chromolly tubing..and they both cost the same. Aprx 7 lbs per foot. 

##  The strongest thing up there should be the mast, bar none.   Have you
ever
seen a mast failure ?   Total gong show.  Imagine a mast, folded at 90 degs,

right
above the top of the tower...with yagis mounted on it.   Now what are you
gonna 
do ?  
Tower stays intact of course, but the folded mast is a complete mess.


##  Typ 1026 DOM masts are  2.875 OD  x .25 wall, also galvanized.   Yield 
strength on the version that 
array solutions sells is 87 ksi.      The CM version sold by dx eng is aprx
107 
ksi.   The problem with
2.875 od material is getting mating bearings for it.  Also a lot of rotor
mast 
clamps  are for 3 inch,
and would have to be shimmed.   kurt andrress  will custom make a 2.875 mast

clamp  for stuff
like  PP rotors  or OR-2800  etc, etc.  

##  do it right the 1st time.  Then install mast steps so you can safely
climb 
the mast. 
Pay once, cry once..but do it right. 

##  Run the mast calcs  for  87 ksi 1026 DOM  in a 2.875 x .25 wall.....VS 
107-115 ksi 4130 CM  in a 3.00  x .25 wall...and you will be amazed. 

Jim   VE7RF