C-A glue for pin blocks

BSimon1234@AOL.COM BSimon1234@AOL.COM
Sat, 8 May 1999 04:09:05 EDT


Paul Larudee writes:

 <<please correct and advise me as necessary.>>

This is much easier than you think.

<<1.  Loosen 1/4 turn or so, slip off the coil and turn the pin up a
little higher than it should be when at tension.  This is so that a) it
will be at the right height when finished, and b) the glue will form
evenly at all points on the pin, which it would not if it were under
tension.>>

No. Just hit it with the CA and accellerator  where it is. Don't loosen it, 
don't take off the coil, etc.

<<2.  With the action out of the piano and plastic sheeting on the key
bed, apply accelerator to the under side of the pin block at the problem
area.  This is so that any glue that might be tempted to drip will
harden before doing so.  The plastic is in case that fails.>>

No - for just one pin slip a foot square sheet of alum foil above the action, 
below the area of the pin. You are only going to put on a few drops, less 
than one  cc.

<<3.  Apply low viscosity (red label) glue to the base of the pin, using a
well sealed hypo syringe (which I guess is trash after the procedure). 
Allow the glue to wick down until the pin won't take any more.  Let
harden completely.>>

No. -Get a 1/2 or 1 oz. small bottle of the CA glue, put a capillary tip on 
it and apply with that.  You should see it flow around the bae of the pin. 
Don't apply forever. Give it a good sploosh, let it sit a minute, give it 
another good sploosh, applying only around the pin, not out onto the plate, 
not up onto the coil.  Let that soak in, then put a very tiny drop of 
accellerator at the base of the pin. You might see the residue of the CA glue 
"freeze" solid. I would leave it alone for several hours, a day or two is 
better, but it is possible that 10 minutes might also work.

<<4.  Clean the underside of the pin block; install and tighten jack. 
Whack pin just enough to break glue contact.  Turn pin to point lightly
above surrounding pins, replace coil, bring to tension and tune.>>

No.  It is unlikely that there will be a residue on the underside, especially 
for just one pin. The  drips come from treating the entire pinblock en masse 
with several ounces of CA glue.

<<How's that?

The above advice is just my opinion, it is the way I would do it,  but I bet 
it works better than the elaborate scheme you were intending. If the torque 
is insufficient, support and tap. If the current pin torque is above 15 inch 
pounds, it is unlikely that tapping is manditory. The CA treatment quite 
possibly will be enough.

Some questions:

<<Q#1:  When the pin gets whacked, does it really separate cleanly from
the surrounding wood (and the glue itself).  Why doesn't some of the
glue remain on the pin, possibly along with bits of wood from the block?>>

Support the pinblock if you need to whack the pin, but I would just put the 
tuning hammer on the pin, knock it flat a bit, then tune. If things went 
well, you will likely hear the crack of a jumping pin, once, releasing the 
pin to be tuned. I treated quite a few pins in experimentation months ago, 
and just went and got the pieces of pinblock and cut them apart on the band 
saw. I sawed a few pins out from the block. The pins were essentially clean, 
the glue was into the wood, no fibers torn out at all. Perhaps it was because 
the pins I experimented on were new and plated? ( I started with pin torque 
of zero, with the pins able to fall through the holes,  and got up to 80 
in/lbs with two treatments.

<<Q#2:  Why doesn't the pin bind and jump during tuning from rubbing
against a plastic and possibly uneven surface?>>

Don't know, but none of the ones I have treated ever bound up or jumped, 
except for the initial break-a-way.

Why not experiment on a scrap piece of pinblock in your shop before 
experimenting on the customer's piano?

My 2 cents.

Bill Simon
Phoenix


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