Re: [TowerTalk] Which Thrust Bearing to Use

[Grant Saviers <grants2@pacbell.net>]

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@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
> >
> >
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