I haven't read all the responses to this thread, so, sorry if this is redundant. There's a faster way than boring with a forstner bit and putting a nut on the back. I've performed this type of repair several times in the good ole days. We would run slow set epoxy into the separation, remove one plate bolt at a time (this way you don't have drop string tension), drill the plate bolt hole all the way through the back, install a T-nut in the back, and then run a long machine bolt through the front into the T-nut. If aesthetics are a concern, you can spring for chrome bolts and washers. Typically, we didn't have to use clamps, but Don's suggestion to clamp is well worth considering. I'd venture to guess that this repair on 70's era Baldwins paid several mortgage payments for me .
Michael Spreeman http://www.spreemanpianoinnovations.com
From: pianolover88 at hotmail.comTo: pianotech at ptg.orgSubject: RE: Upright pinblock questionDate: Sun, 28 Oct 2007 08:20:44 -0700
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.comTo: pianotech at ptg.orgSubject: RE: Upright pinblock questionDate: 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 88Sent: Sunday, October 28, 2007 12:18 AMTo: Pianotech ListSubject: 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 -0300From: jrpiano at win.eastlink.caSubject: Re: Upright pinblock questionTo: 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. RossWindsor, Nova Scotia, Canadajrpiano 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.htmTerry Peterson
Date: Sat, 27 Oct 2007 23:44:28 -0300From: jrpiano at win.eastlink.caSubject: Re: Upright pinblock questionTo: 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. RossWindsor, Nova Scotia, Canadajrpiano 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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