GO RENT A CONCRETE SAW WITH AN ABRASIVE BLADE IN IT SINCE THE SAW IS A CHAIN
SAW ENGINE YOU COULD LAY IT FLAT TO CUT THE TUBE.
N9IWW
-----Original Message-----
From: towertalk-request@contesting.com
Sent: Sunday, July 27, 2014 12:00 PM
To: towertalk@contesting.com
Subject: TowerTalk Digest, Vol 139, Issue 44
Send TowerTalk mailing list submissions to
towertalk@contesting.com
To subscribe or unsubscribe via the World Wide Web, visit
http://lists.contesting.com/mailman/listinfo/towertalk
or, via email, send a message with subject or body 'help' to
towertalk-request@contesting.com
You can reach the person managing the list at
towertalk-owner@contesting.com
When replying, please edit your Subject line so it is more specific
than "Re: Contents of TowerTalk digest..."
Today's Topics:
1. Re: Cutting 2" Heavy Wall Cr-Mo Mast Up on Tower (Grant Saviers)
2. Fwd: Cutting 2" Heavy Wall Cr-Mo Mast Up on (Jim Thomson)
3. Re: Cutting 2" Heavy Wall Cr-Mo Mast Up on Tower (Pete Smith N4ZR)
----------------------------------------------------------------------
Message: 1
Date: Sat, 26 Jul 2014 22:24:28 -0700
From: Grant Saviers <grants2@pacbell.net>
To: Charles Gallo <charlie@thegallos.com>
Cc: "<towertalk@contesting.com>" <towertalk@contesting.com>
Subject: Re: [TowerTalk] Cutting 2" Heavy Wall Cr-Mo Mast Up on Tower
Message-ID: <53D48D0C.6070700@pacbell.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
If the CrMo is heat treated (and as hard as it should be) then all you
will get is a dull blade in a portable bandsaw. A carbide tipped blade
may work, but are fragile, a tungsten carbide abrasive coated blade will
definitely work, but $$. Several cutoff blades 4 1/2" grinder will also
get it done, but why and how safely, and where is the cut off piece
going to go?
Grant KZ1W
On 7/26/2014 10:56 AM, Charles Gallo wrote:
Cordless portable bandsaw
--
73 de KG2V
Charlie
On Jul 26, 2014, at 1:47 PM, "Victor Walz" <n2pp@frontiernet.net> wrote:
I have a 22 ft (2" OD) heavy duty Cr-Mo mast presently installed up on a
100
ft Rohn 45 tower. It weighs 200+ pounds. I previously had a 4 el 20
meter
yagi stacked 12 ft. above a 40 meter F12 yagi. I just finished
removing
both antennas for repairs and have decided not to reinstall the stack due
to
the complexity of the installation. I will be re-installing the 40
meter
yagi and some VHF antennas on this tower. Consequently, I would like to
shorten the 22 ft mast by 10 ft.
I am looking for advice on the most efficient way to cut this very thick
high strength mast in place. I would prefer to use battery-operated
tools
such as a reciprocating saw(metal blade?) or a grinding tool (cutting
wheel?). I can run 120 VAC (about 200 ft extension cord) up the tower if
needed.
What would be the optimum method for cutting this mast without excessive
tower time? Thanks in advance for any responses.
Vic, N2PP
_______________________________________________
_______________________________________________
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
------------------------------
Message: 2
Date: Sun, 27 Jul 2014 03:13:32 -0700
From: "Jim Thomson" <jim.thom@telus.net>
To: <towertalk@contesting.com>
Subject: [TowerTalk] Fwd: Cutting 2" Heavy Wall Cr-Mo Mast Up on
Message-ID: <E81B3A33156F4DAA8EC13E369C2EA783@JimPC>
Content-Type: text/plain; charset="utf-8"
Date: Sat, 26 Jul 2014 14:27:25 -0400 (EDT)
From: Hans Hammarquist via TowerTalk <towertalk@contesting.com>
To: towertalk@contesting.com
Subject: [TowerTalk] Fwd: Cutting 2" Heavy Wall Cr-Mo Mast Up on
Tower
Beside wonder how you are going to handle the cut-off piece, I would try a
regular tube cutter. I am using one with carbide wheels and that seems to
cut anything. Nothing but hand power is used.
Good luck but be careful.
Hans ? N2JFS
## His 22 foot mast weighs 200++ lbs.......which implies it has a half
inch thick wall thickness. A 2 inch od mast..with a .375 inch wall is
only 7 lbs per foot. No way in hell you are gonna cut 4130 heat treated
chromolly steel, with a half inch thick wall...with any tubing cutter.
## BTW, once the mast is .25 inch thick, going any thicker is really a
waste of effort. At that point you should use a bigger OD mast, like 2.5
or even 3.0 inch OD. A 2 inch mast with a .375 inch thick wall,
weighs the same as a 2.875 inch mast with a .25inch wall thickness.....
both of em weigh the same 7 lbs per foot. The 2.875 inch od mast will be
one helluva lot stronger, even factoring in the bigger diam masts windload.
And that assumes the 2.875 inch mast is DOM, with 89 ksi yield
strength..... vs the 2 inch mast with its .375 wall being made from 4130
chromolly steel with 107 ksi yield.
## I use a 2.0 inch od mast with a .375 wall thickness...... cuz its
stronger than a 2 inch mast with a .25 wall. However, that was not my
choice..since the HDX-689 I bought used was all setup for a 2 inch mast.
If I was doing this from scratch, I would opt for either a 2.875 inch od x
.25 inch wall DOM mast..... or a 3.0 od mast with a .25 inch wall...made
from 4130 chromolly steel. The strongest mast I ever heard about was 3
inch OD with a .375 wall..made from 4130 chromolly. That mast would weigh
10 lbs per foot..same as the fellow with his 2 inch od mast and .5 inch
thick wall.
## U can see the effect right away using any of the popular mast programs.
watch out, the DOM stuff will vary from 75 ksi to 89 ksi..depending on
where you buy it. 4130 chromolly will vary from 107 ksi up to 125 ksi.
The yield strength makes a huge difference of course. Section modulus
x yield strength = bending moment.
Jim VE7RF
------------------------------
Message: 3
Date: Sun, 27 Jul 2014 10:55:40 -0400
From: Pete Smith N4ZR <n4zr@contesting.com>
To: towertalk@contesting.com
Subject: Re: [TowerTalk] Cutting 2" Heavy Wall Cr-Mo Mast Up on Tower
Message-ID: <53D512EC.1040205@contesting.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I would leave it - in case you ever decide to do something else, you
can't uncut the mast.
73, Pete N4ZR
Check out the Reverse Beacon Network at
http://reversebeacon.net,
blog at reversebeacon.blogspot.com.
For spots, please go to your favorite
ARC V6 or VE7CC DX cluster node.
On 7/27/2014 1:24 AM, Grant Saviers wrote:
If the CrMo is heat treated (and as hard as it should be) then all you
will get is a dull blade in a portable bandsaw. A carbide tipped
blade may work, but are fragile, a tungsten carbide abrasive coated
blade will definitely work, but $$. Several cutoff blades 4 1/2"
grinder will also get it done, but why and how safely, and where is
the cut off piece going to go?
Grant KZ1W
On 7/26/2014 10:56 AM, Charles Gallo wrote:
Cordless portable bandsaw
--
73 de KG2V
Charlie
On Jul 26, 2014, at 1:47 PM, "Victor Walz" <n2pp@frontiernet.net>
wrote:
I have a 22 ft (2" OD) heavy duty Cr-Mo mast presently installed up
on a 100
ft Rohn 45 tower. It weighs 200+ pounds. I previously had a 4 el 20
meter
yagi stacked 12 ft. above a 40 meter F12 yagi. I just finished
removing
both antennas for repairs and have decided not to reinstall the
stack due to
the complexity of the installation. I will be re-installing the
40 meter
yagi and some VHF antennas on this tower. Consequently, I would
like to
shorten the 22 ft mast by 10 ft.
I am looking for advice on the most efficient way to cut this very
thick
high strength mast in place. I would prefer to use battery-operated
tools
such as a reciprocating saw(metal blade?) or a grinding tool (cutting
wheel?). I can run 120 VAC (about 200 ft extension cord) up the
tower if
needed.
What would be the optimum method for cutting this mast without
excessive
tower time? Thanks in advance for any responses.
Vic, N2PP
_______________________________________________
_______________________________________________
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
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
Subject: Digest Footer
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
------------------------------
End of TowerTalk Digest, Vol 139, Issue 44
******************************************
_______________________________________________
_______________________________________________
TowerTalk mailing list
TowerTalk@contesting.com
http://lists.contesting.com/mailman/listinfo/towertalk
|