High(!) touchweight

[Jon Page]

Ron,
Something to consider, instead of resetting the capstan for the purpose
of a lower touchweight, reset it for the purpose of getting the wippen to
travel
optimally in it's arc so the jack is just in front of the knuckle when the
key is at
the bottom of the keystroke. 

So before  you move the capstan, observe the location of the jack with the key
depressed. If it is being buried into the stop felt at the end of the
balancier, you
have sufficient grounds to reset, of course the action needs to be
regulated to
fully determine this.

Lower t/w is a by-product of moving the capstan. I've had occasions to need to
move the capstans towards the back of the key. The KR in those cases was .45
to .48. The jack wasn't clearing the knuckle enough and I did not want to
increase
the key dip.

On one B, I moved a few samples 1/4" forwards and still did not get a short
enough
arc motion on the wippen. The customer did not want the expense of
relocating the
wippen cushions so I shortened the dip slightly and brought the L/O as
close as I could
without running into problems with humidity changes. On this piano you
could observe
a 1/16" space between the f/r punching and the key at the time the jack was
buried into
the stop felt. Talk about stressing the jack glue joint. 

So if you want to move something to affect touchweight, try the knuckle.
Moving that
from 15.5mm to 17 (if appropriate) has dramatic results. In the few tests I
have done
it even lowered the friction. With the knuckle closer to the center pin, it
has inherent
friction qualities.

First time in CAUT, even though I mostly service the 20 pianos at the 
Cape Cod Conservatory of Music and Art is that college and university enough?

Jon Page
Harwich Port, Cape Cod, Mass. (jpage@capecod.net)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
At 09:23 PM 9/17/98 -0700, you wrote:
>This device was not intended to set static key weight.  It was intended
only to
>help establish the correct position of the capstan by optimising the
>key-to-hammer-lever ratio.
>
>-- ddf
>
>---------------------------
>
>Ron Torrella wrote:
>
>> I've done a little bit of experimenting with capstan location using a gig
>> similar to the one Del described. (See below for a description.) The
>> results are interesting.
>>
>> NOTE: This is another B [#352489] that has the same leverage problem.
>> Renner wips and shanks, NY hammers, Pratt-Read keyboard, "accelerated
>> action" (read "lotsa lead!"). Essentially, the same keyboard as the one I
>> mentioned before, only this one has Renner parts. The key bushing are new
>> and eased correctly.  The centers on the shanks and wips are loose --
>> probably will be re-pinned because they're outside of "shop tolerance."
>> The piano was restrung this summer, oversized pins, original pinblock.
>> Given that small amount of background....
>>
>> I removed capstans at No.s 1, 20, 21, 37, 51, 68 & 88, but because I had a
>> short amount of time to work with, I only managed to get through the first
>> five. On #1, the original capstan location downweight was 64, up was 36. I
>> moved the capstan location 1/8" toward the balance rail and got 60 down,
>> 34 up.  Not bad, but not close enough to ideal for me. Note #20, moved
>> 1/8" only got me to 59 and 31. Note #21 was a distaster.  Had to move the
>> capstan 1/4" and that *only* got me down to 59 and 30.  Note #37 went down
>> to 60 and 38 with 1/8" movement.  And note #51 only got to 53 and 28 at
>> 1/8".
>>
>> Can't move capstans any more than 3/16" without the capstan contacting
>> wood. 1/8" would be fine, except it means drilling out the capstan holes
>> *oversized*, plugging and redrilling.  If I didn't oversize the old holes,
>> drilling new ones would be straddling old and new wood.  If I used pine
>> plugs (not dowels....plugs cut from scrapped keyboards), I *may* be able
>> to get away with "normal"  sized plugs, but there's still a glue joint to
>> deal with. (Have I started splitting hairs yet?)
>>
>> I'm contemplating the option of a combination of things; move the capstans
>> no more than 3/16" *and* swap small keyleads for medium or large ones. The
>> net result would be a lighter touch (improved leverage), but a slightly
>> heavier keyboard (on the order of 150-200grams or 5-7 lbs, overall, is a
>> guess).
>>
>> The other option is to install those "turbo" wippens from Renner.  I tried
>> a few of those and they're pretty slick.  The manhours involved with
>> re-pinning and regulating those wippens would be about the same as the
>> current wippens (I don't think that stuff has been done yet).
>>
>> Anyone wanna hazard a guess at which route will take longer?
>>
>> Ron Torrella, RPT
>> Piano Technician
>> University of Michigan
>> School of Music
>
>
>
>
>