[pianotech] balance hole jig

[Ron Nossaman]

On 7/27/2012 8:23 AM, jim at grandpianosolutions.com wrote:

> This jig works if it has a flat plane to sit on.

Which will be the case in pretty much any case. The indexing will work 
whether the jig is making contact with the key through it's full length 
or not.

In the instance of adding partially recessed shoes, as in your photo, 
the outboard index pins will have to extend beyond where the shoe will 
go, and the balance hole located by these pins after the shoe is 
installed. One can likely come up with all sorts of imaginary scenarios 
where this will surely be impossible, but in practice it works quite 
easily and nicely. A strip of scrap maple works fine for a jig. Lay out 
the balance hole and the two bridge pin locators, freehand and drill 
press time of a couple of minutes. A center rail pin in the balance 
hole, assuming you're replicating the hole location, indexes the jig on 
the key. Clamp it and drill or just punch the outer index locations on 
the key bottom. Next key. Mortise keys, install shoes, locate center 
hole with jig, drill.

For non mortised shoes, added to increase key depth and stiffness, you 
can either do the same thing, or pre-drill and rough cut shoes with the 
center hole (sort of like installing key buttons), index them on the key 
with a center rail pin as you glue and clamp them on, and not need a jig 
at all. Again, this is if you're replicating the hole location. Finish 
up by reaming hole depth from the top, with the tool mentioned a few 
days ago, and you're there.


> My question was how common is it for the sole to project.

Before or after your procedure? It depends on what you're doing.
Ron N