on rib notching

[Gene Nelson]

Thanks for the info - I take it that you pattern and route the mortises 
prior to gluing on the ribs? Maybe I will try this next time - this time 
ribs are glued on the board prior to mortising the inner rim.
Gene
----- Original Message ----- 
From: "Ron Nossaman" <rnossaman at cox.net>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Friday, November 02, 2007 12:35 PM
Subject: Re: on rib notching


>
>> Would anyone care to share their technique for locating and notching rib 
>> ends into the inner rim?
>
> I make a Masonite pattern, and rout the mortises - an idea stolen from Del 
> Fandrich. I don't know if he originated it, but the mortises found in 
> Baldwins look similar.
>
>
>> My first piano I used two sided tape on the rib ends and set the board 
>> in - the tape stuck to the inner rim and I used this to cut the notch.
>
> I tape the ribs in the mortises with locater pins in the rib ends, then 
> drop the panel in so the pins mark it for later assembly outside the 
> piano.
>
>
>> This was not as accurate as I would have liked.
>> Some of the other problems were the shape of the rib end - being tapered 
>> presented some difficulty with this notching - trying to match the taper 
>> was not easy. On the second piano the rib ends are flat.
>> Also the depth of the notch - should the depth of notch exactly match rib 
>> end hight? Be slightly deeper?
>
> I make the mortises both deeper and wider than the rib ends. There's no 
> mechanical or acoustic reason to fit the ribs to the mortise.
>
>
>> How thick or thin should the rib end be? Thinner is better in my mind.
>
> I cut mine about 4.5mm.
>
>
>> Is there a limit on how thin?
>
> They don't even have to be mortised into the rim at all, except there may 
> be a tendency for the panel to crack on the bent side where the grain runs 
> tangent to the inside curve.
>
> Ron N
>
>