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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