[CAUT] Digest, Vol 1103, Issue 85 Moving Wippen Rail

[Keith Roberts]

Hi Rick, I think measuring to the top of the jack is just easier and the
figures work close enough but really the line to the top of the jack is an
imaginary RA. I want to eventually work up the proofs for what I am talking
about. I think eventually the proof will write itself but I will need the
education that will come as I finish off my engineering degree to bring it
all together. There is so much to consider when moving action parts. Jon
Page is intuitive with his stack move. He knows when it works. David Love
knows when the rail move will work. Each action is different sometimes. Just
a mm here and there but what a difference it can make. Essentially you have
to know the effects all the way through the action. David Stanwood has
worked through the effects of the changes he recommends after measuring it
his way. He cannot predict anything that will happen if you don't take the
measurments his way. This doesn't mean his is the only way of looking at an
action or that it is exactly correct.
It is my insistance that the lever carries the jack. Just by the very
definition of the terms lever and jack, the jack is not part of the lever,
it is a jack. I can make it of any length and the force at the end will be
the same. The last sentence if the key. I can make the jack any length and
the force out the end is the same. How then can I measure the RA to the top
of the jack?

Keith Roberts


On 10/31/07, Richard Brekne <ricb at pianostemmer.no> wrote:
>
> Hey there Keith.
>
> Dale is a guy I have a lot of respect for, so I take your words and his
> reports and my ears are definitely open. That said,  I have measured
> friction change that I attribute to the knuckle / jack top interface
> with any significant angle change in the jack at rest.  Where we may be
> on different tracks here is just how big the window for adjustment is.
> You mention 1-2 mm of spread... I think in terms of jack angle at rest.
> Tho I did mention there was some credence given to the idea that the
> jacks angle could be just a bit on the  B + side, albeit just a tad.
>
> My point tho, I'll hold on too.  Whippen spread, capstan position...etc
> are best set from geometric concerns.  You can get all the leverage
> issues worked out you want without any incompatibility here.  Thats my
> take on Stanwood as well.  And I have an awful lot of respect for
> David.  Sure you can place the capstan further in or out without any
> other consideration then changing the ratio and make it work.... but
> often as not thats shooting in geometric dark.  Strikes me as best to
> change the action leverage from a geometric perspective... and then
> balance it.  Simply looking away from geometric issues by reseting
> leverage and balancing at the same time ala Stanwood doesnt add up in my
> mind... especially since the former is every bit as easy to begin with.
>
> While we are on this bit about Ratios... there's one that seems always
> forgotten in the mixing up of ratio measurments that are better to my
> mind left separate for what they respectively are.  And that is the
> ratio of speed.  Overs made a rather large point of this some years back
> especially as it relates to the jack speed.  My point is that there is a
> lot of this stuff we really dont have all that great a handle on.  True
> enough we get some rather smooth running actions each in our own, if not
> entirely dissimilar ways... but I like to stay a bit on the safe side,
> as far as my viewpoint allows for at any given time.
>
> Cheers
> RicB
>
>
>
>
>
>    Ok Rick, the only problem I have is the friction is measurable is it
>    not? It
>    was measured. There was no change in a wippen move of 1 to 2 mm. The
>    action
>    was weighed off. Not to the DW but the BW. Dale Erwin custom
>    balances his
>    actions. He said there was change in the weight of the keys due to a
>    change
>    in leverage. He did not believe friction had anything to do with the
>    change.
>    I'm not arguing, I'm only reporting actual measuring. You will have to
>    discuss with Dale how he weighs his action and why he thinks
>    friction had
>    nothing to do. Me, I'm going to take his word that he measured and
>    interpreted the data properly.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/caut.php/attachments/20071031/295c38ca/attachment-0001.html