Could I use a flat head "stove" bolt, since that's the type of screw head that's in there now? this type of bolt will fit perfectly in the place of the screw since it is the same shape, then I could go front to back, and just recess the back hole with a forstner bit, and cap it off so it looks nice. Oh, it's been almost 24 hours since the PR, and the tuning is holding fine with no drop in pitch.
PS: Again, should I use, or do I even need to use locking washers over the standard washer to help keep the nut snug?
Terry Peterson
From: donmannino at ca.rr.com
To: pianotech at ptg.org
Subject: RE: Upright pinblock question
Date: Sun, 28 Oct 2007 05:08:47 -0700
Terry,
With the tension lowered the crack
will likely close up, maybe not all the way but most of the way. The
pinblock / plate has been disconnected from the back posts, and this is not a
good recipe for tuning stability or long life of the piano. This is
actually a pretty serious crack your pictures show, and at full tension will
likely get worse.
Carriage bolts are put in from the
rear because it presents a neater installation from the outside of the piano,
where people are most likely to see it. Also, the carriage bolts will seat
into the wood of the back to stop them from turning, but from the front you
would have to grind at the plate to get them to seat.
Lowering tension is recommended in
order to make sure you can clamp things up completely, but it does add a lot of
work elsewhere - it's likely you'll need to clean up string spacing, for
instance. But it is still recommended. If you do it without lowering
tension, then you need to use clamps next to the bolt and change one bolt at a
time.
If you lower tension, remove top
screws all at once, apply epoxy and clamp all along the top (watch out for
glue-squeeze underneath - it can drip on the customer's floor!). Drill and
install carriage bolts, tighten everything up, and wait a day for the glue to
dry.
Come back, remove clamps, pull up to
pitch, clean up string spacing, then re-tune the piano again. Follow up in
about a month with one more tuning . . . .
And the piano is good for another 40
years!
:-)
Don Mannino (from
Atlanta)
From: pianotech-bounces at ptg.org
[mailto:pianotech-bounces at ptg.org] On Behalf Of pianolover
88
Sent: Sunday, October 28, 2007 12:18 AM
To: Pianotech
List
Subject: RE: Upright pinblock question
Out of curiosity, why put the bolts in from the back to front, and
not the reverse? Also, should "lock" washers also be used to keep the nuts
from loosening? FYI, I used a feller gauge to check if the gap widened
at all during the massive pitch raise, and there was no difference noted, and
several hours later, the pitch seems to be holding fine. Also fyi, I'm
attributing the 130+ cents flatness on the fact that the piano had not been
tuned since 1969 when it was first purchased!
I don't know why
manufacturers don't use long bolts & nuts in the first place to secure the
pinblocks; seems that would save having to do it down the road.
Ok,
looks like even though the separation is extremely minute, I have decided to
replace *all* the top screws (7) from left to right with the carriage bolts
washers and nuts. But I'd much rather install them from front to rear with the nuts on
the *back*. Is there a reason Not to do it this way? And just how
tight should I cinch down the bolts? As long as there is uniform tightness all
the way across, like there currently is with the screws, can they be torqued
about the same tightness as the screws?
I also don't see why I need to
detune the entire piano, or significantly lower string tension to do this. For
example if I start with a clamp on the first base top screw area, drill out
& replace with bolt & nut, then move on to the next, doing just one at
a time (always maintaining the same pressure with the clamps as the
screws provided) until all 7 are replaced, would I not end up with successful
job?
I could see maybe if the separation was much wider, that
de-stressing the plate might allow the separation to close up easier, but what
I have at the moment is only about 1mm, so I don't know how important it would
be to close that gap, as compared to simply stopping it from getting any wider
by using bolts that go all the way through. And it also seems like pretty good
news that after that massive PR it didn't get any wider...yet!
Terry Peterson
Date: Sun, 28 Oct 2007 03:21:06 -0300
From:
jrpiano at win.eastlink.ca
Subject: Re: Upright pinblock question
To:
pianotech at ptg.org
I use carriage bolts from behind. Acorn
nuts could be used in front, if you are worried about the
looks.
I wouldn't be worried about a nut being
visible, as lets face it, you are saving the piano.
John M. Ross
Windsor, Nova Scotia, Canada
jrpiano at win.eastlink.ca
-----
Original Message -----
From:
pianolover 88
To:
Pianotech
List
Sent:
Sunday, October 28, 2007 12:18 AM
Subject:
RE: Upright pinblock question
I found this site for upright pinblock repair. I know my
situation isn't anywhere near this bad, but I fear it could get worse.
Does this seem like a feasible, reasonable approach? I don't much like the
idea of inserting the bolts from the
back to the front, with big bolts and nuts showing in the
tuning pin area.
http://www.balaams-ass.com/piano/50-pnblk.htm
Terry
Peterson
Date: Sat, 27 Oct 2007 23:44:28 -0300
From:
jrpiano at win.eastlink.ca
Subject: Re: Upright pinblock question
To:
pianotech at ptg.org
See if you can close the gap with
clamps.
If you can, then it needs bolts
through to the back for stability.
If you can't close the gap, then
you would probably be ok with epoxy.
John M. Ross
Windsor, Nova Scotia, Canada
jrpiano at win.eastlink.ca
-----
Original Message -----
From:
pianolover 88
To:
PIANOTECH at PTG.ORG
Sent:
Saturday, October 27, 2007 11:07 PM
Subject:
Upright pinblock question
Recently acquired an amazingly well preserved Kohler
& Campbell art case console made in 1969. To look at it, you would
think that it could have been made yesterday! It has never been played, thus the
hammers are unmarked after almost 40 years! Even the wooden wedge was
still screwed in securing the big panel (some call it the kick panel?)
above the pedals!
Anyway, the pitch was (not surprisingly)
grossly flat--close to 140 cents at A4! I checked all the plate bolts
and they were 90% snug, needing maybe 1/8 turn to totally snug them
back down. The tuning pins were found to be all uniformly tight, and
responded beautifully to minute, incremental adjustments. The pitch
came right up to A440 after the first pass, and after letting it
settle for a while I gave it its first tuning in nearly four decades.
I
followed that with two more fine tunings to make it as solid as
possible for the time being. Ok, now to get to the main reason for my
post; There is, what appears to be a separation, not really a crack
but a perfectly clean separation at least 2-3' behind the pinblock
laminations, that runs the entire width of the pinblock.
As I
stated the pins are uniformly tight, the laminations sound, and the
plate bolts tight. Also, I wanted to know the depth of the separation,
which ranges from maybe 1/2-1 millimeter wide at the very most, so I
used a very thin piece of steel and found that it was only about
1/4'-1/2' deep. Should this flaw be cause for concern, or is it likely
not going to affect the stability? The tuning seems to be holding, but
then I just finished it maybe an hour ago so...
Would it maybe
help to 'fill' this crevice with thin west systems epoxy, until it
fills the area, then just let it dry and move on, or would that just
be a waste of time and epoxy? Or maybe Gap filling CA? Of course, it
would take quite a of CA to fill a 56' long, 1/2' deep cevice!
Thoughts and advice would be appreciated!
PS: See the
pics.
Terry Peterson
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