Balance rail felt

[V T]

Hello Bob,

Yes, I think that once compressed and installed the
thinner punchings will stay compressed.  It was just
easier to gain some insight into the punching
stability by doing the experiment this way (mere
curiosity.)

Humidity change seems to be the major factor in
swelling them.  Ultimately, I think I will keep them
on a rod until installation time, as Ron suggested.  

Vladan

=============================================

You said you are going to let the felt sit without
compression for a few days and then measure again. 
However, if you compress the punching by some method
and then put in on the b. rail pin with the action on
top won't it stay compressed by having a key and
action stack weight sitting on it?  

Bob Hull

--- V T <pianovt@yahoo.com> wrote:

> Hello Bob,
> 
> I proceeded with some experiments:  I have all the
> Pianotek balance rail punchings, so I measured the
> compression on them for a given force (nothing
> elaborate - just a simple comparison).  Then I
> ironed
> them and measured again.  Interestingly, the
> thinnest
> punching (1mm) was not the low compression winner
> after ironing!  The 1.8 mm part was firmer after
> ironing.  I am letting them sit without compression
> to
> see how much they spring back.  I suspect that the
> 1.8
> mm part will be worse than the 1 mm part in a few
> days.  Just for reference, the 1 mm part would
> compress about 0.006" before ironing and 0.003"
> after
> ironing.  The 1.8 mm punching would compress 0.009"
> before ironing and 0.002" afterwards.  I expect that
> heat has a different effect from compressing on a
> threaded rod, so I will repeat that experiment with
> Ron's method.


		
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