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[TowerTalk] Re: Ham IV rotor installation

To: <>
Subject: [TowerTalk] Re: Ham IV rotor installation
From: (
Date: Mon, 17 Sep 2001 23:08:30 -0600
It's pretty easy to over tighten a small bolt to failure.
"Snug enough" is the answer :-)  GL defining it.

I shim my rotors but I have long forgotten what material
I used.  Some have reported using some sort of rubber
sheet around the mast for added gripping ability.  If you
can find a suitable thickness / firmness, that might be a
good solution.  Any suggestions?

Using a single thrust bearing puts considerable side 
load on the rotor which can cause excessive wear on
the rotor.  I prefer to let the full weight of the mast and 
antennas rest on the rotor to help keep the ball bearings 
in their race and reduce wear caused by sideloading.

Tom  N4KG

On Mon, 17 Sep 2001  Tom Anderson <> writes:
> >
> > A few questions:
> >
> > 1. Does anyone know if HyGain ever established any bolt torque 
> > for the mast clamp, especially the single bolt in the center that
> > rests against the mast itself.  I asked Norm and he said just 
> tighten
> > them as much as possible mentioning I probably couldn't break it.
> > I've snapped too many bolts to have faith in that idea.  I even 
> asked
> > about drilling a hole in the mast, but he warned that would weaken 
> the
> > mast (10 ft .125 wall 2  inch steel mast with the rotor about 2 
> feet
> > below the thrust bearing).
> >
> > 2. Does anyone ever actually "shim" the mast since HyGain said the
> > rotor is designed for a 2 1/16 mast and the 1/32 in. shims each 
> side
> > are necessary to center the 2 inch mast. No one I've talked to 
> ever
> > said
> > they "shimmed" any rotor. If so what do you use for shim stock?
> >
> > 3.  Do you allow the weight of the mast and antennas (Mosley 
> Classic
> > 33 WARC with 40m kit & Hygain 2m/440 vertical) to rest directly on 
> the
> > rotor or do you lift it slightly and tighten the thrust bearing so 
> the
> > rotor is just responsible for turning the antenna and mast, not
> > holding the downward weight of the mast and antenna?  Thrust 
> bearing
> > is heavy duty supplied by Tri Ex in 1993, WELL greased  1-2 times 
> a
> > year with marine bearing grease.  Rotor previously turned a Mosley 
> TA
> > 33 Jr. and a Cushcraft 2 meter all mode 15 element beam.
> >
> > Any help appreciated, since I'm not sure all the damage to the 
> rotor
> > was caused by lightning, Norn said some internal parts were 
> "chewed
> > up."
> >
> > Tom, WW5L
> > Colleyville, Texas

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