On 12/9/16 6:14 AM, charlie@thegallos.com wrote:
Looks really well made. I had the original Rohn counterpart for years and
it just kept on going.
I added a zerk fitting so I could grease it. They last a very long time
dry without lube, but I am anal
about lubing everything hihi.
Bob
K6UJ
Looks nice, but one thing I just have not been able to understand for years
Tower thrust bearings are a LOW rotation speed, high load application,
probably the WORST place to use ball bearings. I would expect either
tapered roller bearings, or today, do what most of industry does, and use
an engineering plastic bearing. I mean, we don't need a torlon bearing
there (the loads are NOT that high)
I mean, a glass reinforced nylon, or a PTFE (Teflon) (say a 25% glass
filled or molly filled) isn't going to cold flow at ALL under loads a 2"
mast could sustain, will NEVER need lubrication, will never corrode etc
You either get them molded for you (for some materials would be the
cheapest way - you do NOT want to know what torlon costs), or you slice it
from tube, or you even just use end on rods set around the circumference
I mean, today they run the pivot bearings and lower boom bearing on cranes
in plastic bearings, because they hold up better than metals in those low
rotation speed, intermittent rotation applications
For amateur use, you could probably buy a slab of the appropriate
plastic from Cadillac or McMaster-Carr, use a hole saw to drill the
hole, drill your mounting holes, and you're done.
Depending on your environment, a stack of HDPE cutting boards might work
just fine, but I don't know about the UV resistance.
Torlon is a bit pricey... $1200 for a 12x12 sheet 1/2" thick
Moly filled Nylon is $37 for a 1" thick piece 6x6" - Says it can be
used outdoors, It's black, but that doesn't always mean it's UV resistant.
Black acetal (Delrin) is $26 for the same 1"x6"x6"
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