[pianotech] First Pinblock

[Mike Spalding]

Terry,

You're absolutely correct about the high density filler being stronger 
than the colloidal silica.  I like that West offers a variety of fillers 
with different properties.  I use several, including the colloidal, high 
density, microlight, and filleting blend.  Each has it's uses.  The 
reason I prefer colloidal silica for pinblock fitting is that I can make 
a mix that is thin enough to flow out of the way when pressed, but which 
won't drip gratuitously while I'm moving the pinblock into position, or 
flow out of the joint while I'm waiting for it to cure.  Strengthwise, 
it only needs to have a compressive strength as high as the maple block 
it's applied to, which my experience tells me it does.

Mike

On 2/3/2013 7:23 AM, Terry Farrell wrote:
> I may be wrong to say the following, but one the occasion when I see a reference to West System epoxy fillers, I see their #406 Colloidal Silica fillers recommended for use in just about any situation. And, in truth, it is a very good filler to use in all situations except when fairing. However, for the highest strength applications their #404 High Density filler is superior. It mixes more easily and is superior for bonding and its hardness. I'm not saying the #406 won't work for the pinblock work here, but why not use the highest strength filler they have when high strength is what you are looking for?
>
> Terry Farrell
>
> On Feb 3, 2013, at 8:07 AM, Mike Spalding wrote:
>
>> Noah,
>>
>> I agree with everything Chuck has said.  In addition:
>>
>> Most likely the new pinblock will need to be fitted to the plate flange.  Do this exactly as you would for a grand piano; i.e. jigsaw as close as you can to original pinblock shape, refine with chalk transfer from plate flange, finish with epoxy (West with colloidal silica filler, not the stringy yellow goop in your photos)..
>>
>> I can't tell from your photos whether your original pinblock is one piece, or split at the tenor block (see attached photos).  Do not split your replacement.  The pinblock will be the main structural member across the top of the piano, don't do anything to weaken it.  Further, I'd recommend that you choose your pinblock material for structural rigidity rather than your preferred tuning pin feel.  Delignit or Falconwood.
>>
>> good luck
>>
>> Mike