[TowerTalk] Noob question re: Thrust Bearings

[jimlux]

On 5/10/20 12:18 PM, Grant Saviers wrote:
> Jim,
> 
> mcmaster.com stocks black UHMW to 5 inches thick in 6x6 and larger 
> sizes.  I've also found it on ebay.
> 
> Grant KZ1W

And, it's a standard item for a lot of the CNC prototype shops.

UV resistant acetal (Delrin) might also work.

The whole thing is sort of a tradeoff on manufacturing complexity vs 
cost - do you just buy a big block of UHMW and machine it, or do you 
have something less expensive and just make the bearing surfaces UHMW.

I believe folks have also used wood.


> 
> On 5/10/2020 09:58, Jim Thomson wrote:
>> Date: Sat, 9 May 2020 16:53:05 -0700
>> From: Grant Saviers <grants2 at pacbell.net>
>> To: towertalk at contesting.com
>> Subject: Re: [TowerTalk] Noob question re: Thrust Bearings
>>
>> <One alternative often
>> <used is a cam locking collar or split collar and some use pillow
>> <bearings made to do that.
>>
>> ##  The  peer  brand  thrust  bearings,  with their  eccentric
>> locking  collars  work  superb,  and  are  used on  UST  tower.
>> The  collars  will  lock  in  either  CW...or  CCW.   They  provide
>> a  hole  on  each  end,  so a drift punch +  hammer is  used to
>> lock  the  eccentric collar is
>>
>>
>>
>> <If two thrust bearings are on a shaft and the loading on each one
>> <becomes indeterminate.  So it is never done in machines.  So ideally the
>> <rotator should have to have no thrust load as mentioned.  Or if it is
>> <intended, you won't know what it is.  However, once the rotator clamps
>> <are tightened there will be something happening when the wind blows, the
>> <tower and mast bend, or the temperature changes, and the top "thrust
>> <bearing" wears.  What??
>>
>> ##  two  thrust  bearings  are  easily  used on a UST  or  other  brand
>> tower.  The  trick  is,  the  lower  bearing  does  not  have  its  
>> eccentric
>> collar  locked  down...or  grub  screws.  Then  NO  binding  will  
>> result.
>>
>>
>>
>> <Then consider the well regarded US Tower crank-ups use a pipe sleeve as
>> <the top bearing.  Zero thrust capacity.  Works well.  Also, doesn't need
>> <separate mast tilt restraints when removing a rotator.  Mast axial
>> <support when servicing a rotator is the only reason IMO to have a thrust
>> <capable bearing on the mast.  A muffler clamp is cheaper.
>>
>> ###   That  pipe  sleeve  +  double  plate  arrangement  used  at the
>> very  top  of  UST  towers  is  super.
>>
>>
>> <My choice is a UV resistant UHMW radial top bearings for low cost, no
>> <maintenance, long life, and low friction.  A 6x6x4" thick block ($47) is
>> <what I made for the 3" mast radial bearing with 500# loading.  In
>> <perfect condition after 6 years.  Some use stacked HDPE cutting boards,
>> <but not UV resistant unless painted.
>>
>> <Grant KZ1W
>>
>> ##  Where  did  u  get  4  inch  thick,  UV  resistant  UHMW ??
>> The  thickest we  have here  in town  is  1  inch thick.
>>
>> Jim   VE7RF
>>
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