[pianotech] balance hole jig

[jim at grandpianosolutions.com]

 > Those sure appear to me to be new shoes.

I forgot to mention. This job is a re-work. The maple shoe and balance 
hole you see there was installed 4 years ago and was in perfect 
condition. However, despite the hole having no slop or shy thousanths, 
the bloody hard maple was clickety-clacking my client into oblivion 
(...it didn't bug me, but I aim to please). This happened with 2 maple 
shoe jobs...needless to say I'm out of the maple shoe business, and 
using basswood on home pianos, and poplar for high use pianos.

So I was not replacing the shoe for this post, just replacing the hole 
in the maple shoe with basswood.

The maple shoes you are looking at were installed 4 years ago as part 
of  the way Bruce Clark  taught a bunch of us to move the existing 
balance hole/ balance rail, to optimize the half stroke locations of all 
the centers in a full action/keyboard redesign. The placement  of that 
entire shoe during the re-design was not indexed off of the original 
holes, because the original holes (in both x,y) were ditched. The 
placement of the new shoe was a procedure and-a-half, which involved 
basically putting the 50" wide keyboard back into the nearest equivalent 
pre-bandsawed apart...it frankly borders on insane in my current way of 
thinking.  If I do this kind of re-design now, it gets a new 
keyset...much less work.

 > If so, what were they indexed to, with all the holes within the span 
of the shoe? Making it long enough that the index pins are beyond the 
span of the shoe would let you locate a center pin hole in a new shoe 
too, as when de-accelerating actions to stiffen keys, eliminating the 
half dowel in favor of a deeper key.

yeah, so if I were keeping the shoe in the original keyboard re-design 4 
years ago, just extending the jig would have worked fine...but that 
ain't what I was up to back then.

While we're on the subject, you bring up something I've been thinking 
about regarding the fulcrum point at the balance pin/hole. So many 
balance rails have the key rotating in a very complex inefficient manor 
in a rocking/chucking motion instead of a true pivot, accentuating the 
required breakaway force at the start of the stroke. I've only dealt 
with the half round dowels once so far. Seems like a good idea.  On a 
short key stick, as opposed to the long D sticks I think you're talking 
about, what are the down sides of the half dowel?  Do they jump around, 
click? Do they create an unstable key height in any way, or are they as 
good an idea as they seem? (there's mostly always engineering tradoffs)

Jim Ialeggio

-- 
Jim Ialeggio
jim at grandpianosolutions.com
(978) 425-9026
Shirley, MA