Well said, Matthew. I believe that's correct. As the plane dries out, it 
shrinks a bit across the grain, tending to narrow the escapement and 
proportionately thinning the cheeks. This can be particularly noticeable 
in planes moving from the UK or Eastern states to drier Western zones.

fwiw
Don

On 2023-09-20 6:08 p.m., Matthew Groves wrote:
> \ufeffIf I\u2019m understanding correctly from some other emails, people are
saying the cheek thickness is increasing due to humidity.
>
> While increased cheek at the escapement thickness could lead to a binding
iron, if the overall piece is experiencing an increase in humidity than the
overall width is going to be growing as well.
>
> Is it possible that the entire body is actually shrinking which would lead to
a binding iron.
>
> The solution remains the same regardless. grinding the iron.
>
> It is my understanding that very old planes are always shrunken in comparison
to their younger selves even when kept at the same humidity.
>
> This (age) is the reason for so many blown cheeks and misaligned profiles,
though of course a move from a higher RH climate to a lower one can exacerbate
the process.
>
> Matthew Groves
> Springfield, MO
>
>
> 
>
>

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