pin blocks

[Richard Anderson]

Elasticity of pinblocks is a subject near and dear to my heart. I've spent a
lot of time looking at that recently. I usually drill delignit with a .266"
bit. When the bit is cool and fed carefully the hole will measure .261", so
don't think that Delignet is inelastic. On the other hand, using a fishtail
bit at excessive speed I was able to end up with a hole that was just .0005"
undersized demonstrating that heat will destroy the elasticity in the area
of the hole. Even reamers will produce an undersized hole (usually only a
thou. or two).

Using the same bore gages that I used for the above, I measured an old 5-ply
maple bock that I was repinning. The holes were over .010" out of round in
each ply. The wide spot was oriented with the grain and thus purpendicular
between the plies giving the hole a "Coke bottle" profile.

Richard



> From: Robert Goodale <rrg@nevada.edu>
> Reply-To: pianotech@ptg.org
> Date: Sat, 13 Nov 1999 09:15:03 -0600
> To: pianotech@ptg.org
> Subject: Re: pin blocks
> 
> Leslie W Bartlett wrote:
> 
>> I'd like to hear some discussion of delignit pin blocks.  I've
>> encountered on  on a Samick (sorry to bring that name up.....) at the
>> church where I do a bit of music, that is causing me some concern.  It
>> has s number of loose pins. I replaced a couple with larger pins about a
>> year ago, and now, they're loose.
> 
> <snip>
> Whether you like or dislike Samick, (let's not go there again this time),
> Delignit blocks are not a Samick product.  They are made in Europe from
> European Beach and widely used there.  Just wanted to clarify that first in
> case there was any question.
> 
> 
>> I tuned a Kawai today that I tuned about a month ago (pitch raise)  At
>> that time it had about thirty very loose pins. Today, pitch was
>> considerably sharp, and the pins were tight.  That's good for now, but
>> what happens with a decade or so and some more dry weather???????????
> 
> <snip>
> Best to my knowledge, (I could be mistaken), Kawai is not using Delignit
> blocks.  I'm certain they are maple.
> 
> 
>> I'm curious as to how more experienced technicians view pinblock
>> materials.
> 
> I don't believe that Delignit is a bad material by any means.  I have used
> it for rebuilds many times with outstanding results: tight and smooth
> feeling pins with no jumping or squeaking whatsoever.  This has not always
> been the case, however, and I think much of this can be attributed to poor
> factory techniques.  Delignit is much more dense than maple, and far less
> elastic.  For this reason the pin holes must be to an exact size with the
> understanding that the dimension is not going to change much once the pin is
> installed.  For this reason a particular sized bit must be used.  I believe
> that one of the problems with new pianos that use these blocks is that the
> control necessary when drilling the holes is often lost.  It is critical
> that the holes be drilled slowly with a sharp and cool bit.  If this rule is
> followed there doesn't seem to be any problem and the blocks come out
> beautifully.  In the case of factory production, however, I think the
> temptation to rush the process is all to frequent.  Thus the bit becomes to
> hot, charring the hole.  The bit is not changed or sharpening frequently
> enough, compounding the heating problem and producing a less accurate
> dimension.  These and other common production related deviance can
> dramatically degrade the results.  Unfortunately these practices give
> Delignit a bad name.
> 
> Rob Goodale, RPT
> Las Vegas, NV
> 
>