Another option is to regalvanize each section. Hot dip galvanizing here
cost me $0.55/lb for 10 x 20' sections of Rohn 65. About $1500 for 20+
years of no maintenance life, good as new, at less than 10% of new
section cost. The prep process requires all paint to be removed (none
on my former AM tower sections). The caustic degrease handles most
organic contamination, then there is an acid bath which removes light
rust and the old Zn, then fluxing and into the vat of molten zinc. Rohn
designs for HDG so both the id and od get new Zn, something you can't do
with paint. Turn around at a very busy Ace Galvanizing in Seattle was 2
weeks. Plan to ream some holes that may have excess Zn in them. ebay
usually has some cheap bridge reamers (ironworker "bridge", not guitar
"bridge") or core drills which in the right sizes are perfect for this
task, or very carefully use a two flute twist drill bit as the soft Zn
will grab.
Grant KZ1W
On 4/23/2015 18:42 PM, Mike Reublin NF4L wrote:
Mike -
If you pull the axle for the pulley, and remove the sheave, you can push a
U-loop of the cable thru the housing and then put the sheave back in.
74, Mike NF4L
On Apr 23, 2015, at 9:27 PM, Mike Ashby <seabassm01@hotmail.com> wrote:
Sam;
I to am in the process of doing the same thing. All of the sheaves were
sluggish and I did not know the history of the cables. Went to Kaman bearing
and bought sealed heavy duty bearings and had a machine shop bore and press the
new bearings into the old sheaves. Much less expensive than new purchase from
U.S. Towers. Went to a rigging supplier and purchased new cables. I purchased
heavy duty cable clamps for the end terminations. The rigging company could
have done the swagging cheaper but the ends would not fit through the sheave
housings. Took the tower to a welding shop and had them grind and weld 2 or 3
spots that had some small hairline cracks. I then went over the entire tower
and put 2 coats of cold galvanizing on questionable spots. 3 coats on the
thrust bearing shelf and rotor shelf. Wire brushed thrust bearing and painted.
Squeezed bearing grease into bearing until old was replaced with new. Bought 2
collar stops to bolt to mast and rest on top of t
he thrust bearing. Going to purchase a funnel to slide down the mast and cover
the thrust bearing for water protection. Have also considered a vent pipe
flashing instead of funnel.
I consider this as a good investment into peace of mind.
Mike
W7PIM
snip
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