[TowerTalk] [Bulk] Re: [Bulk] Re: Top Bearing Plate for 55G vs Rotor Plate

[Grant Saviers]

Don,

Actually, the UHMW bearing design I am using will take axial as well as 
radial loads.  A 6061 collar is SS 1/2-13 set screwed on the mast & 
backs a 5" diameter 1/4" thick 6061 plate fastened to it with FHMS.  The 
UHMW takes the radial loads and the top of the UHMW is the axial (true) 
thrust bearing against the 6061 plate.  Not my invention, Brad K7ZSD 
used this for his 4 side mount 3"x 20' masts as well as the top 
internally mounted rotator/mast.  He used white 3" UHMW which showed 
some crazing and virtually no wear after 7 years, so my upgrade is to 
black 4" UHMW.  I'm using 6" square blocks which makes the boring and 
mounting bolt design easy.  UHMW plate is far cheaper than rod.

Grant KZ1W


On 8/12/2014 10:15 AM, Don wrote:
> THAT is a good idea, the UHMW bored block. Zerk fittings and the plain 
> old typical steel inlanders use go quickly here. Living on the OR 
> coast next to the ocean you learn quickly that putting antennas 
> together and mounting them requires 'different' approaches to keeping 
> them in a low maintenance mode.
>
> I also use the Lear compound, CorrosionBlock, on anything that turns, 
> slides, screws or moves. Won't wash out and has no metals, RF neutral. 
> Put onto this by the fleet folks up in Newport who apply it to all 
> their electrical connections, AC, DC and RF. I've easily taken 
> elements apart where the salt spray has literally 'grown' on the 
> element exterior. It is lightly colored so it is easy to see where you 
> are putting it. See 
> http://www.learchem.com/userfiles/Industrial%20Strength%20Protection.pdf 
> for some information.
>
> Don W7WLL
>
> -----Original Message----- From: Grant Saviers
> Sent: Tuesday, August 12, 2014 9:52 AM
> To: towertalk at contesting.com ; rthorne at rthorne.net
> Subject: Re: [TowerTalk] [Bulk] Re: Top Bearing Plate for 55G vs Rotor 
> Plate
>
> I agree with Steve that a middle bearing is not a good idea as aligning
> 3 bearings is very difficult and a middle bearing serves no purpose at
> rotator rpms.
>
> However, a middle support plate with a removable u-bolt or clamp, that
> can constrain the mast when you want to raise it to remove the rotator
> for service is a big help.  Then the mast stays in column and doesn't
> overload/twist the top bearing.
>
> I also dislike the commercial "thrust" bearings.  A block of black UHMW
> 3" thick bored for the mast od will never need servicing.  Or stack up
> some HDPE kitchen cutting boards bored to fit, but they will need a coat
> of paint to protect them from UV.  A rotator sized for a 4L full size
> 40m beam bearings can easily handle a 500lb thrust load.  btw, my 40m 3L
> full size OWA weighs 350# plus 150# for the 3" x 0.25" wall alloy mast
> (a must for that size antenna).
>
> Grant KZ1W
>
>
> On 8/12/2014 8:04 AM, K7LXC--- via TowerTalk wrote:
>>>   I'm working on getting the parts together for a Rohn 55g  tower.
>> ?  The Rohn 55g Bearing plate sure is expensive.  I see  two other
>> possibilities.
>>
>>>   1 - Use the less expensive beacon plate and drill a hole for the
>> mast/bearing.
>>>   2 - Use a rotor  plate for the same purpose.
>>
>>>   I plan on having a top bearing, an intermediate bearing  then the 
>>> rotor.
>>   I have no idea what the thickness of the Rohn bearing  plate is as
>> compared to a beacon or rotor plate.  I'm hoping to put up  a full 
>> size 4
>> element 40m beam some day, so the system will need to handle a good
>> 300+lbs.
>>
>>
>> Hiya, Rich --
>>   The beacon plate is FB if you don't mind  drilling it.
>>   As for an intermediate bearing, I'd  discourage it. The plates are not
>> precision items and you'll just introduce bind  into the system. 
>> Since all
>> you're trying to do is capture the mast, put the  rotator plate in 
>> the middle
>> and skip the bearing - cheaper too. And the upper TB  carries all the
>> weight anyway so a middle bearing doesn't provide any structural  help.
>>   Cheers & GL,
>> Steve     K7LXC
>> TOWER TECH
>>
>> _______________________________________________
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>>
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