[CAUT] F..riction

[William Monroe]

Hey Dale,

Only the best.............Pearl River GP142.  'Sgot all kinds of problems.
 Of course, that's why I have it.  ;-]

William R. Monroe




On Sat, Dec 4, 2010 at 10:45 AM, Dale Erwin <erwinspiano at aol.com> wrote:

> Hi Bill
>   What type action was it that had balance weights that high?  Just got
> back from a biz trip and this is good thread.
>  Thanks
>
>
>  *Dale S. Erwin
> www.Erwinspiano.com
> Custom piano restoration
> R**onsen piano hammers-sales
> Sitka soundboard panels
> 209-577-8397*
>
>
>
>  -----Original Message-----
> From: William Monroe <bill at a440piano.net>
> To: caut at ptg.org
> Sent: Thu, Dec 2, 2010 3:15 pm
> Subject: Re: [CAUT] F..riction
>
>  Fred Wrote:
>
>  SNIP
>
>
>> Hi David,
>>        Good post. I agree with what you have to say, essentially. I would
>> concur that a reasonable level of consistency in friction is important and
>> desirable.
>>        I'd like to expand on the question of the impact of centerpin
>> friction on touch. (Let me say that from here on, I am not addressing David
>> specifically, but the list in general). Let's start with the hammer, 4 gm
>> vs. 0 gm + a bit. 4 gm measured at one inch translates to less than one gram
>> at the hammer's center of gravity, which is somewhere around five inches out
>> from the center (simple ever, so 4 divided by 5). So pinning a flange that
>> has 0 or so gm friction to increase it to 4 gm would have an impact on the
>> hammer's throw somewhere in the vicinity of impeding its movement by one
>> gram resistance. Intuitively, that doesn't seem like much, doesn't seem like
>> it would have a significant tonal impact by itself: hammer of X mass at Y-Z
>> range of velocity being braked by one gram's resistance, maybe someone on
>> the list has the math and engineering background to do a reasonable
>> modeling.
>>        But let's go back to the key and touch. The friction resistance at
>> the hammer gets multiplied back by 5-ish because of the key/hammer ratio
>> (nominally 5:1 in the opposite direction), so 4 grams friction measured at
>> one inch from the centerpin translates to 4 grams at the key, at least
>> nominally. Or so my calculating brain would say, and maybe someone has
>> measured to confirm: does pinning a flange from 0 to 4 grams increase DW by
>> 4 grams or so? This time of year, I have no time to do other than tuning and
>> the necessary, and I've forgotten what I came up with years ago when I
>> fooled with that.
>>
>
>
> I just happened to be finishing repinning a set of hammers, so took the
> liberty of measuring UW/DW at two different levels of gram resistance in the
> flange.  FWIW:
>
>   Note
>  Hammer Flange Friction (g)
>  DW
>  UW
>  Hammer Flange Friction (g)
>  DW
>  UW
>   3
>  1
>  56
>  34
>  4
>  60
>  32
>   4
>  1
>  55
>  28
>  4
>  59
>  26
>   6
>  1
>  55
>  35
>  4
>  59
>  33
>   8
>  1
>  54
>  32
>  3
>  58
>  31
>   9
>  0
>  54
>  34
>  4
>  57
>  32
>   11
>  1
>  54
>  32
>  4
>  56
>  31
>
> --
> William R. Monroe
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://ptg.org/pipermail/caut.php/attachments/20101204/227bd8cf/attachment-0001.htm>