[TowerTalk] Which Thrust Bearing to Use

[jimlux]

On 12/9/16 6:00 PM, Gene Smar wrote:
>
>
> -----Original Message-----
> From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of
> jimlux
> Sent: Friday, December 09, 2016 12:08 PM
> To: charlie at thegallos.com
> Cc: towertalk at contesting.com
> Subject: Re: [TowerTalk] Which Thrust Bearing to Use
>
> On 12/9/16 8:53 AM, charlie at thegallos.com wrote:
>> <snip>
>>> Your 2" hole that just clears at -40 will be 2.02" at +60C.  I don't
>>> think you're going to have a big problem with that 10 mil extra
> clearance.
>>>
>
> 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.
>
The hole expands more than the mast, because the CTE is larger for the hole

It's slightly counter intuitive - at first glance you'd think the 
material "grows" between the outer edge of the plate and the hole, and 
pushes the hole smaller.  But in reality, the outer edge of the plate 
moves out more.

Consider if you sliced the plate with the hole in half and shoved a shim 
in there that's 10mil. Then slice it on the 90, and shove in another 10 
mil shim. etc.  by the time you're done, the hole is 20 mil bigger in 
diameter.