Knabe Grand/Plugs

[Farrell]

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Although I don't know for sure how long the method I have used will =
last, I do know there are many types of epoxy out there and many of them =
will not necessarily make a strong bond to wood. At =
http://westsystem.com, in the user manual is the process I follow. Also =
in the user manual are all sorts of recommendations for surface prep of =
various woods, methods and guidelines for mixing epoxy and fillers, etc. =
I believe it is imperative that these recommended procedures be followed =
for successful results. An excerpt from the WestSystem web site manual =
follows:
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Two-step bonding
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1. Wet-out bonding surfaces-Apply a neat resin/hardener mixture (without =
fillers) to the surfaces to be joined (Figure 9). Wet out small or tight =
areas with a disposable brush. Wet out larger areas with a foam roller =
or by spreading the resin/hardener mixture evenly over the surface with =
a plastic spreader. You may proceed with step two immediately or any =
time before the wet-out coat reaches the final cure stage.
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2. Apply thickened epoxy to one bonding surface. Modify the =
resin/hardener mixture by stirring in the appropriate filler until it =
becomes thick enough to bridge any gaps between the mating surfaces and =
to prevent "resin-starved" joints. Apply enough of the mixture to one of =
the surfaces, so that a small amount will squeeze out when the surfaces =
are joined together with a force equivalent to a firm hand grip (Figure =
10).
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Thickened epoxy can be applied immediately over the wet-out surface or =
any time before the wet-out reaches its final cure. For most small =
bonding operations, add the filler to the resin/hardener mixture =
remaining in the batch that was used for the wet-out. Mix enough =
resin/hardener for both steps. Add the filler quickly after the surface =
is wet out and allow for a shorter working life of the mixture.
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Used properly, I suspect a good epoxy like West System will hold up at =
least as long as the rest of the pinblock. West System epoxies have been =
used in the marine industry for at least three decades. The iceboats and =
other boats put together with this epoxy experience much more drastic =
climatic condition changes than (most) any piano pinblock will ever see. =
A good example is the use of epoxy for attaching wooden motor mounts to =
boat framing in the bilge. The wood in that area experiences tremendous =
stresses from the motor vibration and torque, and well as repeated =
submersion into water and subsequent drying out, and temperatures =
ranging from below freezing to tropical. It's hard for me to imagine =
plugs not staying put if the epoxy job is done right.
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Still not proof for pinblock plugs. But I feel comfortable with the =
process when done according to manufacturers recommendations. And of =
course, all this is not to say that plugging is better than replacing =
the block!

Terry Farrell
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----- Original Message -----=20
From: "Delwin D Fandrich" <pianobuilders@olynet.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Tuesday, December 31, 2002 12:00 PM
Subject: Re: Knabe Grand/Plugs


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> ----- Original Message -----
> From: "Ron Nossaman" <RNossaman@cox.net>
> To: "Pianotech" <pianotech@ptg.org>
> Sent: December 31, 2002 8:30 AM
> Subject: Re: Knabe Grand/Plugs
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> >
> > >Plugging an intact pin block is often my choice, especially with
> open-faced
> > >types. I use 3/4" plugs so that they interlock. Once that is
> accomplished, I
> > >veneer over the plugs with something like birdseye maple. It is =
really
> nice
> > >looking and has an original finished look about it. The trick is in =
the
> > >"fixture" needed to do all the drilling.
> > >Best Regards,
> > >Joe Garrett, RPT, (Oregon)
> >
> > I've done this with 1/2" plugs and veneer overlay. Drilled with the =
same
> > setup I normally use drilling pinblocks in the piano.
> >
> > Ron N
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> Joe & Ron,
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> I've pretty much resisted doing this through the whole block simply =
because
> I don't trust the structural integrity of the resultant =
plug/glue/epoxy
> mass. Given the vagaries of wood expansion and contraction with =
climate
> changes, just how stable is this some-unpredictable mass going to be =
over,
> say, 30 or 40 years. I've examined several of these jobs done by =
others
> after just a couple of years and have always been able to see at least =
some
> print-through image of the plugs on the veneer face. It's made me =
wonder
> just what is going on down there.
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> Del
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> _______________________________________________
> pianotech list info: https://www.moypiano.com/resources/#archives 
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