Was Buttr. Arch. Q for Ron N - increasing rim density

[Fenton Murray]

Right back at you, Ron O.
----- Original Message ----- 
From: "Overs Pianos" <sec at overspianos.com.au>
To: "Pianotech List" <pianotech at ptg.org>
Sent: Sunday, April 16, 2006 4:14 PM
Subject: Was Buttr. Arch. Q for Ron N - increasing rim density


> Fenton and all,
> 
> At 6:57 AM -0700 16/4/06, Fenton Murray wrote:
> >How about treating the inner rim with a penetrating epoxy?
> 
> Yes that would work, but you need some means of hydraulically driving 
> the glue into the wood. A slightly less messy solution, which I've 
> used for light density rims such as Luaun, is to drill a series of 
> holes into the top face of the inner rim, spacing them about 12 mm or 
> 0.5" apart around the perimeter, drilled to a depth of around 25 mm. 
> The drill diameter is chosen such that the resultant holes are a 
> slight press fit for maple hammer shanks (a couple of test samples in 
> a piece of scrap will allow you to determine which drill size is the 
> most suitable). The drill must be very sharp or it will glaze the 
> surface of the hole, preventing glue from moving into the wood pores. 
> For this type of work it is most important to have a series of drills 
> in 0.1 mm diameter increments from which to choose. We have drill 
> sizes from 1.0 to 10.00 mm in 0.1 mm  steps. They can be purchased at 
> quite reasonable prices in sets. One set from 1.0 - 6.0 mm, and a 
> second set from 6.0 - 10.00 mm. Fill the holes right to the top with 
> Titebond and drive the hammer shanks home to the bottom of the holes. 
> Glue comes out of wood pores everywhere. The clean up is very easy 
> compared to epoxy and the density increase overall is fantastic. A 
> Japanese pull-saw can be used for trimming the excess hammer shank 
> length flush with the top surface of the inner rim after gluing.
> 
> If the belly rail is similarly light-weight, it can be treated in the 
> same manner. Its quite an effective fix for pianos which were built 
> using trash-wood for the inner rim.
> 
> If you use this method, don't forget to leave the case for a couple 
> of weeks to dry out before fitting the new sound board, or it will 
> take ages for the piano to normalise after the rebuild.
> 
> This technique, for hydraulically driving glue, can be used for 
> bolstering back beam joints by drilling holes which diagonally 
> intersect joints, including back beam joints with the rim/belly rail. 
> Before a case is fitted with a new board all joints can be 'injected' 
> using this method from above and below to make sure that the entire 
> length of the joints are 'sound' (flip the case and treat the lower 
> part of the joints, then set it right way up to treat the top part of 
> the joints - all before fitting the sound board). Once you try this 
> it will surprise you how many joints, which look to be OK, really had 
> gaps all over the shop. I suspect that poor back brace joints will 
> suck up energy which might otherwise be helping the sustaining 
> qualities of an instrument.
> 
> Look forward to meeting you in Rochester Fenton.
> 
> Ron O.
> -- 
> OVERS PIANOS - SYDNEY
>     Grand Piano Manufacturers
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> Web http://overspianos.com.au
> mailto:ron at overspianos.com.au
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>