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 > _______________________ > > Web http://overspianos.com.au > mailto:ron at overspianos.com.au > _______________________ > >
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