[pianotech] Making a fully fitted pinblock without measurements

[William Truitt]

Hi Ed:

 

The wedges serve as a visual cross reference to what you and I are doing
with the patterns to confirm that the plate is actually going back where it
is supposed to front to back and side to side,  or at least will give us
some indication of error if it exists in our new block.  They are so quick
and easy to make that it's worth doing for the peace of mind.  I've always
been of the mind that Murphy hates me, he's out to get me, and it is
personal; so anything that gives me more assurance is for the good.

 

I had given much thought to doing the cardboard thing similar to what you
have outlined.  I have had issues at the ends where, even after measuring,
the angle of cut doesn't exactly measure the pencil line, albeit by a small
amount of error.  Hence my desire to make an exact pattern that  would allow
me to duplicate the shape and dimensions of the block to a very fine
tolerance.  How are you making your cuts for the stretcher and sides?

 

How do you take out the nose bolts without removing the plate first?  J
You're a better man than I, Ed!

 

As for the tail rise of the plate, you can drape the foot of the digital
electronic caliper from the top of the rim to a marking on the plate at the
bass end of the tail, record that reading, then undo the rim bolts and the
nose bolt nuts, watch the tail rise and record that measurement.  I've seen
them rise half an inch or more.

 

I don't trust that the plate won't sometimes want to move the pinblock
slightly away from the stretcher at the ends as the plate distorts the
block, so I have drilled my screw holes or dowel holes through the block and
into the rim, and locked the location in place so that it won't move when I
glue the thing in.  My preference is to drill the dowel holes into  and
through the pinblock on the drill press first.  Then I clamp the block to
the stretcher and down at the ends, and drill the holes down into the rim
for the dowels.  That way, it ends up exactly where it is supposed to be,
and cannot be anywhere else.  

 

Maybe I am being too fussy, but I really like the security all this gives
me, particularly since I have recently started doing soundboards - where I
am really paranoid about getting the board and block back  where it is
supposed to be.  I've been rebuilding long enough to have a pretty good idea
how many ways I can throw the monkey wrench into the whirring gears.  You
know, the OH SHIT factor.  

 

Will

 

From: pianotech-bounces at ptg.org [mailto:pianotech-bounces at ptg.org] On Behalf
Of Ed Foote
Sent: Sunday, October 18, 2009 8:53 PM
To: pmc033 at earthlink.net; pianotech at ptg.org
Subject: Re: [pianotech] Making a fully fitted pinblock without measurements

 

Will writes: 

 

 

For some time I have been searching for the Holy Grail of locating the plate
and a new pinblock to the case, without using measurements. 

I have a far simpler method, and it keeps the tolerance to about .020" max.
I do use wedges to measure the side to side, but they are usually not
needed.   I drill two holes in each end of the plate down into the pinblock.
In the treble, the line between these holes is parallel to the side of the
piano, in the bass, it is often parallel to the stretcher. These holes are
the same diameter as a small bridge pin and spaced several inches apart. 


     When the plate is removed, I cut heavy cardboard to fit exactly the
corner of the piano and stretcher and tape them firmly in place.  I then
drop the plate back in, screw it down with a couple or three block screws,
and using the same holes, drill the cardboard.  


     After removing the plate and fitting a new, over sized block to it, I
redrill the holes into the new block.  Then,I undo the block from the plate,
and  by placing the cardboard templates over pins installed in the guide
holes, I can draw a pencil line around the template, giving the the
stretcher dimension as well as the exact end lengths and angles on the ends
of the new block.. I then cut the block, taking the pencil line off the
ends, and by placing a long straightedge along the stretcher lines, I pencil
that in and cut the same way. This block will then be within half a pencil
line of exact, which is plenty close enough. 


   It is also worth mentioning that many plates are flexed down at the tail,
(particularly Steinways), so prior to unscrewing them from the block, I take
out the rim bolts and nose bolts,(making note whether the nose bolts are
holding the plate up or down), and record how much rise the tail exhibits
with a wedge. This wedge will go back under the tail when I begin to
reattach the block to the case.  


   The plate often distorts the block, so I screw the  new one in with all
the screws at the webbing, and then put the whole thing back in the piano
with resin under the ends and resin and dowels into the stretcher.  (The
height has been recorded with a micrometer).  I let that sit overnight, then
remove the plate, drill the dowels into the ends, and glue them in.   That
is about all I need for an exact fit. 


Regards, 

 

Ed Foote RPT


http://www.uk-piano.org/edfoote/index.html

 

  

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