Pinblock Fit

[harvey]

Stan, I thought this question might eventually come up. Let's explore this
a little.

Regarding pinblock to flange fit, you're right. That's one point for Stan.
 
You're right on principal -- that the block either contacts the flange or
it doesn't. For us it is (or should be) a matter of pride --sometimes ego,
to see how well we can mate those surfaces. However, we're doing one
pinblock at a time. Conversely, I've noticed that some rebuilders don't pay
a lot of attention to the top surface (dress or top veneer ply to plate
webbing area as mentioned earlier by Carl Root). Yamaha do! Some rebuilders
are quite casual about drilling for tuning pin angles. Yamaha seems pretty
consistent in this area. 

Now one point for Yamaha. They are right in that (your value) is within
(their) tolerances while installing hundreds of pinblocks while you're
hand-fitting. That's likely because they are using parameters other than
yours (or mine) as to what works... not necessarily what's right. It's also
a polite way of saying, "We build over 100,000 pianos a year for the world
market (and all the baggage that a world market implies). If we were
experiencing gross instability problems, don't you think we would look into
the matter"?

So, where do we go from here? There are some pianos where feeler gauges
give a bogus impression. Others depend on how the feeler gauge is used
(angle of approach, top/bottom or total contact). Still others don't
require feeler gauges -- one could drive a truck through the gaps, yet they
don't exhibit the characteristics associated with having gaps. On these
pianos, it is a mechanical improbability to minutely fit the block to the
flange at certain junctures -- it's just too time-consuming for the little
return in mechanical gain. Given the opportunity, look at a gutted Kawai
KG-3. Notice the pinblock, then look at the mirror image (how the block
must fit) into the plate webbing area. [Anything built by Chickering is
intentionally omitted, but these had cavities for holding the pinblock(s)
captive.]

Even with certain pianos/models, -we- might be tempted to go the extra mile
with extra fitting, perhaps epoxy or other fillers. Manufacturers don't
typically go to these extremes when production quotas are figured on how
many crated units are waiting at the loading dock at closing time on a
given day.

I'll cut to the chase. You mentioned finding xxx values along the area. You
didn't mention whether this was a cursory check on your part, or if you
found cause to go in pursuit with feeler gauges. Was there any indication
of the pinblock "rocking" on the plate flange? If so, the resulting tuning
instability should be immediately noticeable -- tuning the bass de-tunes
the treble, and vice-versa (or similar sectional characteristics). If the
piano tunes out nicely (short term = now), where is the problem? Therein is
the tolerance. It's either stable or not... yes or no. From a warranty
standpoint, (if that's why you called), I believe tuning instability may be
viable grounds for a warranty claim... the presence of a gap is not.

If tuning stability is found, other avenues may be explored first. One
often overlooked item is that of removing the action, jacking up the
pinblock from the keybed, and tightening all those hard-to-access pinblock
lags. It does make a difference.

In summary, I don't think personal ideology is going to win over
manufacturing expediency and track records on this issue. By now, there are
millions of pianos out there, with gaps, and of assorted denominations and
ethnic backgrounds, that have (and are) providing long and useful service
lives. Paradoxically, these pianos would fail the feeler gauge test in a
heartbeat.

Jim have I got a gap for you Harvey
PS: Conrad, if you're reading this, please acknowledge my order for the UPS
brown, industrial grade flame suit. The check's in the mail.


At 10:15 PM 3/19/99 -0600, Stan wrote:
[intro cut]
>When brought to Yamaha's attention, the official factory response was that
>the gap was "within tolerance".  Is there such a tolerance for pinblock
>fit?  To me, it either contacts the flange or it doesn't.