Ted's glue experiments

[Baldwin Yamaha Piano Centre]

Stephen Birkett wrote:
> 
> Ted wrote:
> > We have dressed the wood (Sitka spruce) to 9.5mm. and tongue and grooved
> > the edges. If this seems a strange thing to do, because we are aware that
> >
> Seems like a whole bunch of work and not necessary...unless the purpose is
> to experiment. You can get tongue and groove router bits that operate on
> large radius and groove sideways (horizontal). The mirror image is
> obtained with a complementary bit. Using an 1/8" bit vertically is very
> stressful on the router and bit, since chips cannot be adequately cleared,
> also very difficult to get tongue and groove in perfect alignment, which
> you say is the only reason you are tonguing and grooving in the first
> place. I would suggest simply pressing the panels down onto a flat glue
> table surface with appropriate flat cauls, before closing up the clamps on
> the edge joints.  You should be able to align the bottom perfectly with
> this method. You can size too if you skip the tongues and grooves,
> although it would probably be ok even with these.
> 
> > one and a half minutes. 15% of urea added to the glue granules, both dry
> > weight, extends this time to about five minutes, which would be enough
> > time. 30% extends the time to around 14 minutes. All the articles I have
> > read seem to agree that urea does not affect the glue strength.
> >
> You are right...I have it from 2 "glue chemists" that urea will not affect
> the strength of the joint. Watch out your glue is thin when using urea, or
> you can get disastrous rubbery stuff that is impossible to squeeze out of
> a joint. Once gelling starts with urea it tkes over almost instantaneously.
> 15% ok, 30% not good...over 25% is questionable that you achieve
> fully cross-linked bonds.
> 
> You can easily glue up your 20 joints and clamp all together in the
> same clamps, if you are short of clamps, before ordinary urea-less thin glue
> gels...try the dribble method.
> 
> Keep up the experiments and tests.
> 
> Stephen
> 
> Stephen Birkett Fortepianos
> Authentic Reproductions of 18th and 19th Century Pianos
> 464 Winchester Drive
> Waterloo, Ontario
> Canada N2T 1K5
> tel: 519-885-2228
> email: birketts@wright.aps.uoguelph.ca
Hi Ted.
       As an addendum to Stephens remarks, try a simple but equal router
cut on each board, this will give you the increased serface area with
out the problems of delicate machineing. Thanks to both of you for your
wisdom in this area.
Have a nice day. Roger.