[TowerTalk] Which Thrust Bearing to Use

[Roger (K8RI) on TT]

Except when tho OD is constrained from expanding by a metal with less 
expansion

73

Roger (K8RI).


On 12/9/2016 11:10 PM, Grant Saviers wrote:
> Sure. But since most machining isn't done at -40 deg C, the hole does 
> get smaller when the temperature is lower than when the hole was 
> bored.  I think my calc was correct from a 65 deg F machining 
> temperature.  And the CTE of steel is 20 times less than UHMW so it 
> doesn't matter much in the tolerances.
>
> On 12/9/2016 18:45 PM, Thomas Noel wrote:
>> Absolutely. The circumferential expansion far exceeds the tiny inward 
>> radial expansion.
>>
>> Thomas W Noel
>> KF7RSF
>>
>>> On Dec 9, 2016, at 6:23 PM, charlie at thegallos.com wrote:
>>>
>>> <anip>
>>>> I don't agree.  If the hole is large enough to just clear at -40C, 
>>>> when
>>>> heated the entire mass will increase in volume.  The OD will get 
>>>> larger
>>>> and
>>>> the hole will get smaller and become tighter against the mast.
>>>>
>>>>
>>>> 73 de
>>>> Gene Smar  AD3F
>>>>
>>>>
>>> I guess your science teacher "Back when" didn't do what mine did.  
>>> He had
>>> a steel ball (on a handle, and a steel ring (ditto).  At room temp, the
>>> ball would NOT fit through the ring - maybe 1/32 of interference.  You
>>> then took the ring, put it in a bunsen burner, and hot it hot 
>>> (didn't even
>>> need to be red) - the ball fit though perfectly
>>>
>>> Yep, the way materials expand the hole gets bigger.  We do it in the 
>>> shop
>>> ALL the time, heat a gear etc to make the hole bigger to drop over a 
>>> shaft
>>>
>>>
>>> _______________________________________________
>>>
>>>
>>>
>>> _______________________________________________
>>> TowerTalk mailing list
>>> TowerTalk at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/towertalk
>> _______________________________________________
>>
>>
>>
>> _______________________________________________
>> TowerTalk mailing list
>> TowerTalk at contesting.com
>> http://lists.contesting.com/mailman/listinfo/towertalk
>>
>
> _______________________________________________
>
>
>
> _______________________________________________
> TowerTalk mailing list
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk


-- 

73

Roger (K8RI)