[pianotech] Old Upright Blues

Susan Kline skline at peak.org
Sat Jan 22 14:49:58 MST 2011


Ah, someone has written Grrrrrrrrrrrrrrr!!! (I love it, what an 
invitation!!) I'm using a different type face for interspersed comments ...

On 1/22/2011 4:57 AM, Terry Farrell wrote:
>> Oh, the note you fix will be just fine. But since it was loose from 
>> cracks down below in the first place,the bigger pin will spread the 
>> cracks and the neighboring notes will be toast.
>
> The pinblock is cracked? How do you know? Yes, I agree this might be 
> the case, but IMHO it is at least as likely, if not more so, that the 
> tuning pin hole has simply enlarged from pinblock shrinking and 
> swelling and perhaps pin friction over the many years. In that case, 
> the bigger pin should work fine and not affect neighboring pins.

The pinblock is cracked ... well, one can guess. Do you think that the 
tuning pin hole can enlarge from pinblock shrinkage far enough that it 
can't be tuned, yet the wood can avoid having cracks and delaminations? 
Have you ever seen firewood which sat and dried out? It cracks ... you 
can tell how dry it is by how much it has cracked. And if the pinblock 
is miraculously not cracked, but is dry and old and fragile, guess what 
shoving a bigger pin into it is going to do?   [CRACK] Have you ever 
driven in oversized pins and not had the neighboring notes loosen? I 
haven't. But then, it's been a long, long time since I've used anything 
except CA on loose pins.
>
>> Besides, the CA glue does wonders. And it's not that the pin is 
>> suddenly too small -- it's that the hole got too big. Exactly like 
>> stripped screw holes, with the same kind of drawbacks when putting in 
>> bigger pieces of metal instead of repairing the hole.
>
> Hold the phone here. I thought we had a cracked pinblock? Now the hole 
> has simply enlarged? And what pray-tell is fundamentally wrong with a 
> larger screw as a remedy for a stripped screw hole (as long as the 
> larger screw is large enough to bite into un-chewed-up wood)?
> Grrrrrrrrrrrrrrrrrrrr!!! *;-)*
GRIN!! There's a TREMENDOUS fundamental problem with stuffing a bigger 
or a longer or a bigger AND longer screw into a stripped hole! Screws go 
THROUGH other parts. That's why they are there, to hold other parts on. 
They need to pass freely through the other part. Get them too big, and 
they will seize in the other part. Then it will seem that the screw is 
tight, but it will be tight in the wrong part, and still loose in the 
stripped hole.

Besides, the trouble is not that the screw is too small! The screw is 
still exactly the same size it always was. The trouble is that the hole 
is too large! It is the hole which has changed, so it is the hole which 
needs fixing. Besides, if you fix the hole, you already have the right 
screw and don't have to supply one. Plus it will still match the others.

Years and years ago, Jeff Hickey wrote a very helpful post on the list 
to people talking about elaborate plugging procedures for dowels inside 
Steinway action rails which no longer were able to hold flange screws 
properly. He said, 'You guys are working way too hard!' and then he 
talked about using a strip of buckskin soaked in white glue and putting 
that in the hole (with none sticking out the top). He had a somewhat 
careful procedure for determining how big the strip should be, and for 
making sure that the screw didn't shove the leather ahead of itself, and 
for making sure that the glue and leather were somewhat hardened and 
shaped before reassembling the parts.

I dispensed with some of that (sorry, Jeff), and used the leather and 
white glue thing for numerous enlarged holes, from the tiny continuous 
hinge holes of grand lids to the massive lyre screw holes of cheap 
grands. I used everything from tiny strips of buckskin so small that one 
used tweezers to pick them up to thick hunks of shoe leather which had 
to be carved with a knife. I very seldom had failures of any kind, and 
some of these repairs I visited years later and found them still in good 
form. The squishy glue-wet leather forms new threads around the screws, 
and then the threads harden rock-hard. White glue never (or almost 
never) grabs on metal hard enough to seize a screw, unlike CA or epoxy. 
Wet leather stretched over a wooden frame and allowed to dry made 
shields in the Middle Ages. Wet leather which has dried is tremendously 
tough, so it essentially rebuilds the threads in the holes so that the 
screws can be taken in and out just like when they were new. The white 
glue also gloms together the splinters and sawdust in the holes, so that 
the stripping stops. This idea has served me very well, and compared 
with jamming a too-large screw into a stripped hole and waiting for it, 
in turn, to either jam in the other part or strip out itself in due 
course, I think that mending the hole is the way to go.

<smile>

Susan

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