Summary of: "To pin or not to pin"
-------------------------------------
What's the weight and turning radius of your proposed antenna? The
G-800 is a pretty medium duty rotator and 14+ sq.ft. may exceed its
capacity.
In answer to your question, I don't recommend pinning the mast.
First of
all, drilling your 4130 will be a pretty tough job. That's the first
reason
NOT to do it.
Second is that when you take a big gust of wind, not having the
mast
pinned will allow the mast to rotate slightly. If it's pinned, what you
find
out is what the next weak link in the system is - and it's usually the
gear
train. It's much easier and cheaper to recalibrate the antennas
occasionally
than it is to swap and repair rotators.
As you're probably aware, the Yaesu mast clamps will crack at the
slightest provocation. Be sure to follow their instructions.
Cheers, Steve K7LXC
--------------------------------------------------------------------
But, Steve, Yaesu's instructions are very explicit in telling us to pin
with
the bolt provided! When I, as a believer in non-pinning, called Yaesu's
tech
support, I was told I must pin. Actually, considering that the 800SD(X)
has
no brake, this might be the proper thing to do. We can either crank the
hell
out of the clamps with no pin, and risk cracking them, or snug-em up
gently
per Yaesu's directions and pin. Wind blown rotation in the case of these
rotators will just change its azimuth since there's no brake ("braking
torque" is a result of gear-reduction and friction). With no brake,
there
should be less risk of gear failure. So...I pinned. When the wind blows
it
around, I just turn it back where it belongs. Just trying to follow the
'Prime Directive' ;>).
Chuck, N4NM
--------------------------------------------------------------------
The antenna will tend to turn in the clamps otherwise, and if you
tighten
them enough to hold without the pin, they tend to break. Yaesu USA told
me
that they tried to get the factory to change to steel, but without
avail.
On mine (-1000SDX), I went with a pin, but I purposely used one that is
smaller than the standard. My theory is that in a really extreme
situation
the pin might shear before the rotor died. So far I haven't had to find
out!
There have also been threads on Towertalk about materials that can be
used
between the clamp and mast to increase friction. The one I liked best
was
high-friction industrial belting scraps -- you might check the archive.
73, Pete Smith N4ZR
n4zr@contesting.com
-----------------------------------------------------------------------------
Jack,
I would pin it for sure. My experience is that when a pin I had broke,
the antenna just spun within the clam shells of the SDX 1000. In fact,
I
had two pins from Yaesu break, so I replaced theirs with a stainless
steel
pin and have not had any trouble. The clam shell clamp will not hold
your
antenna, it is not strong enough, you need the pin.
73, Bruce K1XR
------------------------------------------------------------------------------
Okay, okay - I'll concede the point.
The original poster asked about *his* situation. I stand by my
advice to
'not pin' since he's dealing with 4130 which will be a bear to drill.
It's
more of a practical consideration to me. I guess with the Yaesu
'prone-to-break' clamps, they're just ensuring that the mast won't slip
inside the clamps.
Cheers, Steve K7LXC
--------------------------------------------------------------------------------
Hi all,
I use Yaesu rotors and big KLM antennas, and have tried it both ways.
Obviously, there is no way to keep the KLMs from turning in the puny
Yaesu
clamps, so I've opted to pin. However, if you use Yaesu's supplied pin,
it
will simply shear off on both ends at the first gust of wind, so you
MUST
use SS bolts.
Yes, the 4130 was a bear to drill through, but if you start with brand
new
titanium-tipped bits and go from smaller to larger while using some
lubrication (and you exercise some patience, as well), you'll eventually
get
through. And I never have to re-orient the antennas (KT-34XA & 40M4 on
same
mast) anymore. They used to spin like tops!
73 de Jeff K2KV
k2kv@reallybig.com
------------------------------------------------------------------------------
From:
"Barry Kutner" <w2up@mindspring.com>
To:
towertalk@contesting.com
I also pin the mast which holds a TH7 and Cushcraft 402CD turned
by a T2X. Been up there almost 10 years. A few years ago, while
up on the tower, I noted the bolt was cracked in half! I forget the
exact alloy, but it was a high strength steel with some Beryllium in
it. I did replace it with another bolt, and so far, it's still in one
piece,
last I checked.
Regarding drilling, I first tried with a standard bit - wouldn't dent
the
stuff. Then, bought a Cobalt tipped bit labelled "for hardened metals
including stainless steel." With some cutting oil, went thru like
butter.
73 Barry
-------------------------------------------------------------------------------
You guys have me worried mentioning how hard it is to
drill 4130. Just put a 20 foot stick of 4130 1/4inch wall
in my tower. I drilled 2 holes 3/8 diameter through it to
pin it to a prop pitch to mast coupler with grade 8 bolts.
Had no trouble drilling it with standard drill bits and a
battery powered Makita drill. Took a little pressure, and
started it with 1/4 bit then drilled it out to 3/8.. yes I
checked the mast, it was stamped with a mil spec number
and 4130 printed all along the length. Sure hope its real
stuff when the wind and ice hit it this winter. Have another
piece here of 13/4 4130 that I cut with a hacksaw, didnt
seem that hard either. Or do I have good blades?
73 Merv K9FD
-----------------------------------------------------------------
Greetings:
It is not advisable to pin the mast to the rotor. In fact, many
manufacturers of rotors tell you that if you do pin the mast
in the rotor, you'll void their warranty.
If you feel you need the additional "security," then a better idea
is to pin the antenna's to the mast and leave the mast free in
the rotor. This way, if it does spin under a load, it is easier to spin
the mast back to where it should be than to spin an individual antenna
somewhere up the mast.
I never pin both the antennas and the mast...if you do and a big
blow comes along, you have practically guaranteed that *something*
will break.
73, J.P. W2XX
-------------------------------------------------------------------
From:
Dick Flanagan <dick@libelle.com>
To:
Tower-Talk Reflector <towertalk@contesting.com>
>In a message dated 99-09-06 17:49:54 EDT, clewis@ro.com writes:
>
>> But, Steve, Yaesu's instructions are very explicit in telling us to
pin with
>> the bolt provided!
[...]
> Okay, okay - I'll concede the point.
>
> The original poster asked about *his* situation. I stand by my
advice to
>'not pin' since he's dealing with 4130 which will be a bear to drill.
It's
>more of a practical consideration to me. I guess with the Yaesu
>'prone-to-break' clamps, they're just ensuring that the mast won't slip
>inside the clamps.
Just as another data point, M2 specifically directs you NOT to pin the
mast to their Orion 2800 rotors. If you do, it will void your warranty.
Actually, I'm glad they said that because I didn't want to try to drill
my 4130 anyway! :)
73, Dick
--
Dick Flanagan W6OLD
-------------------------------------------------------------------------------
I did not have any trouble drilling 4130 mast either
Tony
N2TK
-------------------------------------------------------------------
From:
"Dan 'Hank' Arney" <kn6di@groupone.net>
For the life of me I do not understand what the big deal is of drilling
4130. If you use a SHARP drill, correct SPEED, exert a fair amount of
PRESSURE and some lubricant it is like a hot knife going through butter.
If you are doing it all correct you should get nice little spirals as
the drill eats up the 4130, if you are getting chips then you are doing
all of the above WRONG
You can double drill it if like 3/8 or 1/2" with a 3/16 or 1/4"
With the correct flute angles you can drill SS and plastics just as
well.
My .02 centavos
Hank
-----------------------------------------------------------------------------
Thanks Hank for the info, thought it was just me going senile,
I use quality drill bits from a machine shop and they go through
very easy. Speed is very important depending on drill size..
Maybe the ones having trouble use wallmart bits and run the
drill at 5000 rpm ? 73 Merv k9FD
-------------------------------------------------------------------------------
Several years ago, when I first got my G-1000SDX, I asked Yaesu USA
about
the mast clamps/pinning issue. I was told at the time that they had
asked
the factory to change over to a more durable clamp design, and the
factory's response was to add the bosses and drilling for the pinning
bolt,
while sticking with the old material. Presumably the new production
clamps
are as weak as the old ones, because the tightening instructions haven't
changed.
By the way, my G-1000 does have a brake -- a tiny drum, so identified on
the blow-up drawing of the rotator itself. Also has a spec for braking
torque, so maybe it's different from the G-800 in this respect, though
the
control boxes are identical.
73, Pete N4ZR
--------------------------------------------------------------------------
For whatever anecdotes are worth, I'm turning a Force 12 C-3/Short 40
combination with a pinned G-1000SDX, and have not had any signs of
trouble
in 3+ years, including some pretty fierce winds. Since the Yaesu design
is
not a worm gear drive, and the brake drum is a very small device without
the wedging design of the T2X-style, my hunch is that in a real pinch
the
brake drum will simply slip, at least until things hit the stop at one
end
or the other of rotation. Maybe they assume that in most cases the
antenna
will windmill into equilibrium before that occurs.
73, Pete N4ZR
-----------------------------------------------------------------------------
Hello Jack,
As reported in prior posts, having some weight on the rotator is a good
thing, as they are designed for a vertical load, which helps keep their
bearings seated and wearing evenly. This also seems to help them resist
lateral loads from wind, which try to push the mast back-and-forth down
at
the rotator level. Just be sure you are not over-loading the rotator
weight-wise.
What I did was to install a second thrust bearing above the rotator.
During normal operation, I have the clamping bolts tight on the upper
thrust
bearing and loose on the lower bearing, with all the weight being taken
by
the rotator (I also have a Yaesu 800 SDX). For maintenance, I lift the
mast
and antenna assembly up just enough to clear the rotator, and tighten
the
clamp bolts on both bearings to hold it in place. Then I can remove the
rotator.
--...MARK_N1LO...--
------------------------------------------------------------------------------
I do not believe you can make a blanket statement like that.
I do not buy for one minute that pressure on the rotor is needed
for sealing, or any reason. The use of two thrust bearings is ideal,
as this removes ALL weight and keeps the mast centered in high
winds.
IMHO, the less work a rotor is required to do, the longer it will last.
(((73)))
Phil, K5PC
---------------------------------------------------------------------------
From: Tom Champlin <w0hh@grapevine.net>
To: <towertalk@contesting.com>
Sent: Monday, September 06, 1999 7:57 PM
Subject: [TowerTalk] To Pin!
>
> I have always pinned with my Yaesu G2800SDX. The clamshells show no
> signs of wear or cracking. I have done this with my 20M4 (114lbs). and
^^^^^
This (wear) is the key reason for pinning -
IMHO.
Any one who has had a knurled nut slip in a tool the first time and get
stripped knows how
much harder it is to get any purhcase on it the second time. The inside
of
the clamps have
"teeth", made of cast aluminum that provide the gripping capacity. Spin
the
mast around
a few times and they begin to lose their grip. From then on it is a
vicious
cycle of tightening
and slipping to the point where the clamp breaks.
Solution pin it and let the rotor (brakeless Yaesu 800 that I have)
give.
The manufacturers' suggestion.
Regards,
Rajiv, N2RD
-----------------------------------------------------------------------------
Thanks, W3TMZ
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