Changing roller size.

[Roger Jolly]

Hi Jon,
            So there is some Englishman in you, Roller indeed??????
Just the observation's on Steinway's when some one installs the wrong
knuckles,and the severe alteration in touch weight, power, and repitition.
Not enough case studies to offer an opinion. O ther than the whole action
is screwed up. <G>

Regard Roger




At 09:03 AM 01/09/00 -0400, you wrote:
>Graeme,
>
>I have not experimented with this alteration but I can envision a few of 
>its consequences.
>
>With each size smaller roller, the capstan would have to be turned up to 
>raise the wippen
>to maintain hammer blow. My concern would be where the 'magic line' 
>intersects the
>capstan/wippen cushion contact. So if it came down to altering knuckle 
>height to correct
>the magic line juncture (I'll call it the median line); I'd sooner change 
>the capstan location
>to improve leverage.
>
>Also a smaller knuckle would have the jack clearing it sooner due to its 
>diminished radius.
>With this decreased connection period, will it affect the dynamic control?
>
>As to how this attenuation might affect leverage, I can not speculate.
>
>I've limited my knuckle selection to the center pin to roller core radius. 
>As pointed out
>during the Renner USA  class in Arlington, as the c/p to knuckle radius 
>increases; so does the
>knuckle diameter so as to maintain wippen attitude within the system. So 
>the 15.5 mm radius has
>the 9mm knuckle and the 16.2 & 17 mm radii have the 10mm roller.
>
>Anyone do some "scientific" rescearch?
>
>Jon Page
>
>
>At 08:52 PM 09/01/2000 +1200, you wrote:
>>Hi list,
>>
>>I was speaking with a technician friend last night and we were discussing
>>another tech acquaintance (quite respected locally) who has been replacing
>>grand rollers (knuckles to some of you) with smaller sized ones.
>>
>>In his opinion he achieves a finer regulation, faster repetition etc etc.
>>So as I understand it he is say replacing a 10mm roller with 9mm and
>>sometimes 8mm.
>>
>>My take on this is that the geometry would be altered elsewhere. I'm not
>>knowledgable enough though to know what the possible negative effects could
>>be, if indeed there are any.
>>
>>Could some of you with experience in this throw some light on this, whether
>>it works well or not at all.
>>
>>I'm curious to say the least.......
>>
>>Many thanks,
>>
>>Graeme Harvey
>>New Plymouth
>>New Zealand.
>
>Jon Page,   piano technician
>Harwich Port, Cape Cod, Mass.
>mailto:jonpage@mediaone.net
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
Roger Jolly
Saskatoon, Canada.
306-665-0213
Fax 652-0505