Changing roller size.

[Ron Overs]

 Jon, Roger and list,

Further  comments on a smaller roller/knuckle.

We often opt for a smaller knuckle, than the typical 10.5 mm diameter, 
when overhauling modern actions. This is very often possible since, for 
some reason, it is not uncommon for the wippen heel to be somewhat deeper 
than ideal, ie. the mean contact point of the capstan/heel is often 
slightly below the line from the wippen centre to the balance pin hole.

In the event of the capstan contact being positioned below the line of 
centres, the installation of  a smaller knuckle will improve the fiction 
situation for both the jack/knuckle and capstan/wippen heel contacts. I 
am assuming here that we talking about the typical modern action with 
99mm centre distance between the wippen flange and jack centres.

However, we make no changes before calculating the hammer/key ratio and 
the influence of any proposed changes on the friction loses throughout 
the entire action.

Regards,

Ron Overs

Overs Pianos, Sydney Australia
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Email:   sec@overspianos.com.au
Website: www.overspianos.com.au
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