Hi,

I have a new client where the pinblock is separating from the core. There is nothing unusual about how this is occurring. It's the same pattern I'm sure we have all seen before.

The piano is also a bit more than 1/2-step low, so I shouldn't need to drop the tension to make the repair.

Normally, I would just drill, insert the bolts and glue, etc. one day. Then, return a day or two later, after the glue has had time to dry and cure, to pull the piano to pitch and fine tune.

But, this client lives a significant distance from me. To save her money, and save me time and gasoline, is there a way to reliably get all this accomplished in just one trip? Can all this be done in one trip and leave her with results as good as would normally take two trips?

Thanks,
-Joe

I have done it in 1 visit

probably 1 visit only. May be no need to make the tension lower than it is
is there any reinforcing part ?(I suppose the pinblock is open) ?
if possible a larger hole so the bolts does not protrude too much on the back if you cnnot find thick enough bolts with round head) (to avoid marks an the wall mostly)
the customer is certainly not exigent

A lot depends on how severe the separation is. Caught early enough, most are cosmetic and can be done without making a grand production out of it.

I have done 2-3 day servicing as an overnight house guest or staying at an hotel on expenses. Usually it is more formal if I am working on behalf of a company.

The only reason for an extra visit is the ts the tuning stability question and we have all done pitch raises that stayed put longer than they had any right to.

I would have no problem doIng the job and leaving subsequent tunings to a local tuner even when cost isn't an issue.

In the past, I have dropped the pitch very low to facilitate getting the gap closed tightly. Dropping the pitch by only 1/2 step from A 440 does not accomplish hardly anything regarding getting the pinblock back into original position. If you can do the repair with the piano at its present pitch, good for you. It sure makes things easier re: tuning stability afterward.

Thank you everyone for the replies. They are helpful
That's something that I really like about this forum... the brainstorming that's possible.

Isaac, The plate does extend all that way to the top.
The separation isn't excessive, but it is quite visible. It seems widest in the upper tenor/low treble area. Naturally, this is also the area that has gone the flattest.
This is a young couple starting out. So, they do need to conserve their resources.

I just wondered if anyone here has developed a strategy for making this repair, including pitch raise and fine tuning, in one trip... maybe by using C/A glue with yellow glue, or some other approach.

Maybe I'll stay with what I know. It seem that there is a good possibility that it could all be done in one trip, but that there are no guarantees as to tuning stability.

Thanks

If you use bolts that go right thru to the back of the piano, regular carpenter's glue sets in an hour. So I don't see how you could not do it. Extra clamps and wood blocks to keep from marring the plate would help as well.

Hi Jean,

I know it will set, but I think it takes about 12 hours or so to cure and reach its maximum strength. But, maybe most curing takes place earlier in the process with diminishing returns as the glue continues to cure?

Thanks,
-Joe

Yes, and the bolts will hold it.

I actually think in this case, since you won't be lowering the pitch more than it is now, it will actually allow you to pitch raise it 2 or 3 hours later. Just take that time to check regulation, vacuum, clean, go for lunch etc..

All the best.

That makes good sense. Make the repair, take a break. Maybe go to lunch and/or check out the local B&N or other stores, or Christmas shop, come back and tune after 3 hours or so.

Thank you, Jean.

-Joe

A pleasure, hope it goes well.

Tape off each side of the open joint. Mix up some slow setting (and thin) epoxy and, using a syringe, lay a bead along the length of the open joint. Using a thin metal strip -- I use a long, very thin fillet knife -- work as much epoxy into the open joint as you can, refilling as you go. When you have filled the opening completely tighten the screws/bolts/whatever and pull the piano to pitch.

Slow setting epoxy will keep seeping into the open joint for some time so it may be necessary to keep filling it up for a time. It will go places ordinary glue never thought of going. Eventually it will fill up. Clean everything up, fine tune the thing and go home.

ddf

If gaps are left, epoxy is the way to go, for sure. In a customer's home far away, it involves a lot of preparation.

If you think that with new bolts counter sunk right through to the back of the piano will work, do a dry fit first, just see if the bolts can actually pull the assembly back together, then use carpenter's glue and just squeeze the thing.

If not, epoxy for sure.

If the piano still has good sound, as is, just fill it with epoxy, like Del said. Just prevent it to go further.

How wide is the separation, 1 mm or 2?

Joe,

I know that time is of the essence in this case. Nevertheless, I wanted to ask whether you'd be prepared to make a few snapshots of the defect (before, during, after repair) and post them afterwards - perhaps in some album to which you can provide the link here.

I've been searching for pictures on pinblock separation (and its repair) for sometime, and though I've found a few, I'd like to learn more about
* where the separation typically takes place, and how to look for it (especially if there's a board or veneer covering the top of the pinblock)
* how large it can sometimes be
* how to repair it, etc.

If, however, you're too busy to take pictures, I understand completely. I just thought I'd ask.

I belive all depends of the type of separation but I would no try to use slow epoxy if it is thin ( I guess it is most of the time) I would be afraid to have to pour half a liter and to have some coming frol below the plate on the soundboard

The bolts are doing most of the job, to me. If they cannot the repair is difficult.

That sort of thing proove how much a plate can bend without breaking..

And that is one of the problems with this kind of repair. How long has the separation been there?

This is why I always use clamps to pull the parts together previous to applying any adhesives. If the separation goes together without breaking the plate then I slacken off the clamps and complete the repair.

Pony clamps on a black pipe usually do the trick. Or large gauge C clamps

Hi Mark and Jean,

If the customer allows, I will take a few pics when I'm there. As they say, a picture is worth a thousand words

Del, I do understand about the advantages of epoxy. But, this will then take two trips, I guess.

I was considering using fresh liquid hide glue. I know hide glue has good gap filling qualities from the player training I've had. The bottled hide glue is just hide glue with urea added to slow drying.

One way I do vary from most folks when making this repair is that I do not like to use carriage bolts. They can rotate in the wood when tightening the nut. Hex head bolts are very controllable from both the head side and the bolt side with a socket set and a wrench. Add a few appropriate washers and a heavy leather gasket on each side. This has always been a very safe approach for me. I have never had a plate crack.

Another way I vary is that I sometimes place the nut on the back. It's easier to cut the excess off the bolt that way, minimizing the risk of any damage to the plate or pins. Then, file things down a bit so there are no sharp edges.

When the glue is dry, if you really want to make things like original, you could remove a bolt at a time, install a hardwood dowel, re-drill, and the reuse the original screws or lag screws.

Mark, one thing to be careful of is the location of the hinges for the lid. You don't want to install bolts and then not be able to re-install the lid hinges.

I've never used liquid hide glue for this job, but have for other jobs. Sounds good to me.

Hi Mark,

The customer consented to having some pics taken and posted online. I'm not much of a photographer, but I gave it a shot.

The pinblock/core/backposts glue joints were originally obscured by green felt. Even though the backposts obviously moved, I assumed that there would also be a separation between the pinblock and the core. After removing some of thwe felt, once I was given the OK to proceed, a different story emerged. Several backposts moved out of position, but the block/core glue joints remained solid. Notice the wavy back.



Below are two more pics of the backposts separating:




Below is a pic of the back after the plate screws were removed (remove one screw, drill, insert bolt, snug up enough to make contact, go to next plate screw...). You will notice that I used several washers, getting wider to trry to distribute the force over a wider area,, including lock washers. i also decided to go with a cork washer made from cork suitable for player gasket work, rather than leather. The plate was very smooth, so i decided to use cork. The reason I use soft washers to contact the plate and the back is that just in case there is some irregularity, the hope is that the soft washer will compress more, rather than applying an extreme amount of force to just one area. The cork washer will later be trimmed when I return to finish the job.



The plate screw hole would have been too far off center from the backpost to have been of any value trying to force it back to its original position. So, I drilled directly through the plate to install a bolt there. I really don't like doing this because there is risk, but in this particular case the risk seemed worth the potential benefit.



Taped off and ready for gluing



Pole clamp to try to pull this separation back. In this case, the screw hole was also off center somewhat from the backpost. Unfortunately, the tuning pins would have interfered with drilling a new hole and the insertion of a bolt in a more ideal location. So, I opted to install a bolt near the backpost, and use a pole clamp overnight to try to pull the gap closed as much as possible.


Since I was working with a slow drying glue, I didn't need to rush to try to close the gaps. These gaps were stubborn. Not wanting to break the plate, I finessed, a little at a time, closing the gaps. I tightened a little, then walked away. Tightened a little, walked away, etc. But after a while, no more glue would come out when I tightened and the gaps would close no further. The only thing that would happen is that the washers would start sinking further into the back.

The job doesn't have to be perfect, just stable. Some of the gaps are not closed completely and one gap was just too stubborn to make a whole lot of progress. I didn't want to force things and risk damaging the plate, so I stopped when it seemed that there could be no further progress. Between the glued and the bolts, the piano should be stable. I will return on Thursday to finish the job and then tune the piano. The tuning will tell me about the success of the repair.

Many thanks, Joe, this was interesting to read.

In all the uprights I've looked at thus far, the top of pinblock/core/back area was covered by some board (often serving as the rear half of a split lid), and in many cases the top part of the back and posts was also covered by some thin board. This has always made me wonder how one can assess a used piano for pinblock separation. It appears to me that one really can't... (other than catastrophic tuning failure or instability.)

Nice clamp Joev.. Thanks for the explanation & pics I would have replaced all the screws by bolts in that case, feel safer..
Those kind of problems are noticed when looking at the back of the piano.

Nice job Joe. Sometimes the separations never close up all the way. After tuning I am sure the client will be elated.

Smaller uprights usually have no board or felt covering this area, but some seem to have a fake top that makes the structure seem more substantial than it really is. Anyway, Mark, you can get a good idea if the pin block has separated by swinging the action out. If it hangs up on the studs, there is probably something wrong.

Mark, most European pianos have the back half of the hinged top securely glued to the top of the pin block, the back posts and the blocking, This creates a "box" with additional strength to hold the pin block in place. But is also makes it more difficult to diagnose a separation in its beginning stages (when you want to catch it!)

Many old and tall N. American uprights have this "back lid" screwed onto the top, with the screw heads hidden under wooden or dubber knobs. It is easier to remove the top and to inspect the pin block from above.

Many more recent studio and console pianos have the top of the pin block either uncovered or only covered with felt, as the one in this thread.

I was said you can diagnose a separation if you can insert a business card between the block and the case (or a thin ruler)

The bck is also bowing then, but certainly th first stages may pass unnoticed unless there is a serious pitch drop

Thanks for the kind words. They are much appreciated.

I'll let you know how things turn out.

-Joe

Hi Isaac,

I also thought of that. But then, I thought back to when I was a student. I asked back then and was told that it's usually best to try to keep some of the original screws if possible. Those specific type of screws in those holes is how the piano was originally designed.

I think ideally, instead of hex head bolts, it would be best to have countersunk screw heads on the bolts. But then, the angles, diameter, etc. would have to match fairly closely the hole from which they were removed.

Yes you are right, a screw tighten more the block than theaded rods. It was a baad idea, probably the 3 bolts are enough to stop the block , indeed the screws have a different role.

We did so on an open block mounting because it ws easy and it allowed to closer better the gap.

Hi Issac,

You are also right. The job requires whatever number of bolts it requires.

Mark,
I just got back from finishing up abd tuning that piano. I did not take any more pics. I was there for quite a while finishing up the job, tuning, and doing some other stuff. It;s not my home and I didn't want to overstay my welcome.

The glue gaps closed about 30% or so more since I was there on Tuesday. It's probably a combination of evaporation of the water in the glue, and the glue being absorbed into the wood. Maybe also the wood itself expanding as the glue was absorbed into it, and the wood itself being held in position by the bolts or clamp. Edit: So, the wood had nowhere else to expand to except inwards towards the gap.

As for drilling the hole through the plate...
This is a spinet piano made by the "Grand Piano Co." I would have been much more hesitant to drill a new hole through the plate if this was a valuable piano.

If you recall, the was one glue joint where I was not able to place a bolt in an optimal position. A s I was driving out today, I considered installing a screw from the back through the backpost into part of the pinblock. After I arrived and looked over the glue joint and saw that it actually closed up more, I felt fairly confident that this would have been unnecessary.

I hack-sawed off the excess from the bolts, filed off any remaining stubs and sharp areas, and refelted the top.

I brought the piano up to 440 and tuned it. There were no problems and the tuning seemed solid.

You mention the gaps closed up "30% more", which means that there were and still are gaps. Evaporative glue (Tightbond etc) is not meant to fill gaps, and it does not have real strength there. That is where epoxy comes in handy and it is the best choice for a gap filling job or for gluing parts that do not mate well.

This is not to criticize your work, but to inform others who read this and need to do a similar repair. I am sure the bolts are doing most of the holding and the piano will be just fine.

Epoxy is fine and appropriate. I like epoxy for this job.

I wanted something that would be very slow drying. These gaps were huge and stubborn. I wanted time to be able to close the gap a little, let the wood relax, close it some more, let the wood relax, etc. I'm also sure that some of the hide glue has managed to work its way somewhat around the sides of the backposts because of the amount of glue I had to use.

Hide glue is used in player work, often to attach the striker pneumatics to the valve board. Those glue joints take a beating. Yet, hide glue will fill some large gaps (when you take things down to scale) and the joints do not separate. In fact, they even maintain their seal.

Also, if that day should ever come when even Grand spinets are valuable because they are made from real wood, the bolts are not epoxied into position. The hide glue can be easily removed.

Also, hide glue was used on most of the old uprights, and many of them are still around.

One reason I think that liquid hide glue has gotten a bad rep is because not everyone is aware that you MUST use fresh liquid hide glue, the earlier from the expiration date the better.

Just keep in mind that you are gluing it with Jello when you use hide glue.

Blech! Jello... Ugh!

Not even the Cos could get me interested in that stuff.

Hi all - I'm working on a write-up for this procedure ( "Repairing the Separated Back")and would like feedback before I finalize it. I've done probably no more than a dozen of these repairs over the years, and want to know if I'm making any serious errors of omission, or if the procedures as I describe them are off base.

Not concerned at this point with proofreading errors. Will proofread myself, and will send it off to my editor who will spot any remaining mistakes. Just more concerned with content. Oh, and if anyone has an idea for a better title - what I have seems lame, but can't put my finger on a better one. Thanks, Chuck Behm

Looks good to me.

Chuck, your articles are always highly informative, easy to understand and well illustrated. I have very much enjoyed every one I have read so far. Thank-you!

Hi Chuck,

I have a question, not a criticism

On page 5
"Once the clamps are removed and before the tension is returned to the strings)the original bolts may be returned (after plugging and retapping the holes)... For a more reliable repair, however, the bolt holes may be drilled all the way through the back of the piano so that threaded rods with nuts and washers on either end might be inserted."
I was wondering if you do decide to go with bolts or all-thread rather than the original screws, if there was some reason you would not want to also use the bolts to help close the gap, rather than waiting until after the glue has set up. Too much tension on one part of the plate? Maybe the holes won't line up as well if drilled at this early stage?

Thanks,
-Joe

Chuck,

Another question: you wrote that the separation is pulled back together until beads of glue are squeezed out. Is it advisable to stop at this point (which really depends on the amount of glue inserted), or to continue and close the separation as far as possible?

Epoxy has good gap-filling properties - in fact, I've read in several epoxy instructions that one should be careful not to over-clamp an epoxied joint, as this may starve the joint of glue. Other glues, however, have weaker gap-filling properties, e.g. all the PVA glues...

That's a great question Joe - thanks for asking.

I see two reasons for not drilling the holes at least until the gap is closed, if not later after the glue has set. The first reason is as you mentioned - the holes won't line up well. If the pinblock is tilted forward to begin with, and you drill your hole perpendicular to the plate, the drill bit is going to follow that line as it goes through the back assembly. When you begin to close the gap, the orientation of the front part of the hole (through the pinblock) and the back part of the hole (through the back assembly) is going to change, so that it's no longer a straight line. It's going to end up with the back part of the hole tilted up from the front part. If you've inserted your threaded rod right after drilling, it's going to bind and prevent the gap from closing. Does that make sense?

Secondly, the 1/2" drill produces lots of wood chips as the hole is drilled. The last thing you would want is for chips to get down in the gap before you try to close it.

To me, it seems safest to drill the holes last. Since the clamps I use are pretty much in the way while they're still in place, I don't do the drilling until the glue has cured and the clamps are removed.

However, that being said, I'll try to do some rewording of the promo to allow for variations in methods here. The audience of the article is not the technician after all (this is not meant to be an instructional article). The audience of the promos I write is the customer of the technician. The last thing I want is to have made things too specific, so that the technician's customer questions him as to why he is doing things one way when the written material he provided said he would be doing it another.

Where various methods are used for a particular repair, I try to be vague enough (or else I mention various possible techniques that might be used) so that the technician doesn't have to explain himself to his customer for having a different technique than I happen to use myself.

Returning to your original question, with the number of clamps that I use, I honestly see no reason to use the bolts and washers as a clamping mechanism. However, I'll try to do a bit of rewording so that if a person did want to use a combination of clamps along with the bolts to tighten up the gap it would fit with what's described in the promo. (If for no other reason, this might be important to the technician who doesn't own a lot of clamps!)

I'll work on revising and post the new copy here for you to check out when I'm done. Thanks again. Chuck

Mark - another good question. When I'm turning down my clamps, I'm getting them as tight as I can, but I'm using Titebond. With the piano in the photographs I put in a lot of glue (using a piece of veneer to work it in) and when the clamps were set I had a running bead of glue showing along the top, but not nearly enough that I was worried that there wasn't enough glue left in the joint to hold.

I'm unfamiliar with how epoxy works for this repair, not having used it ever, I can see your point about not wanting to starve the joint of glue. I'll try to do a bit more rewording of the promo to leave it open as to glue and methods you might chose to use.

Again, keep in mind that this is not meant to be an instructive piece, but more a way for the technician to give his/ her customer enough information to give them the confidence in the procedure to hire the technician to do the job. Chuck

Chuck, you are right about the holes not lining but more about the chips, but I have bring back a block by drilling the original screw hole farther, then installing 2 long rods + washers, and it seemm to work fine (without glue in that case, we had not enough time nor the correct glue, but it can be done later). The separation was local, also (only last treble section).


No particular slip when tuning, later.

I understand I would not sell that as a "repair".

In case the 2 holes are not perfectly lining, up to some point, the rod simply bend, probably (not with an 1/2 inch separation).

Hi chuck,
PVA wood glues like Titebond have cold creep meaning that they can move over time if subjected to prolonged stress, especially if the glue joint is not tight. For that reason I would always replace the screws with bolts to maintain stability of the repair.

As for epoxy, its one of the only adhesives that needs to have some space in the glue joint. Too light a joint can weaken the bond. It is also subject to cold creep so the same procedure as above is recommended.

Thanks for the comment, Bill. I agree 100% - personally, I always bolt with threaded 1/2" rod with nuts and washers on either side. If it's just a hairline crack, I'll advise the owner of the potential problem, and mark a line across it marked on either side at exactly 1" so I can keep an eye on it to make sure it doesn't start spreading.

Again, this write-up is for technicians to give to their customers, and since each promo currently goes out to more than 200 technicians around the country, I try to allow for some "wiggle room" in the details so that technicians don't feel as if they are painted into a corner so to speak.

It's a given that various technicians are going to have their own procedures and specific tools. I'm trying to just give the gist of the repair so that the owner of the piano with potential repair work to be done is satisfied that (1). his piano has a problem which needs to be fixed and (2). the repair proposed is a legitimate one.

In the case of this particular problem and repair, the idea is to be able to give the owner a write-up which legitimatizes the fact that the technician is going to (1).(possibly) pry off the back half of the split lid (which can be easy or very difficult), hopefully not breaking it in the process, (2.) let off nearly all the tension on the strings, thus destroying the tuning, (3.) clamp the wayward plate / pinblock / back assembly together with the sincere hope that nothing breaks (such as the plate!), (4).drill a half dozen or so large holes completely through the back of his piano, (5.) insert large bolts that would look more at home if used on a farm implement and not a musical instrument and (6.) deal with the fact that the piano will probably be in sincere need of a regulation job when the work on the back is completed.

I remember well the first time I proposed this particular job to a customer. I was in my early 20's at the time, the customer in question was a college professor who probably had his fill of young kids my age, and when I tried to explain the work I wanted to do he look at me as if I was suggesting that his wife was a Martian. (He had me do the work eventually, but only after he had called several experience technicians around the area and learned that it was a bona-fide procedure.)

I would have loved to have a well-written explanation of the job complete with photos so that he would have seen that I wasn't just making it up - it was a real repair. It would have made things a lot simpler.

Anyway, I digress. Thanks again, Bill.

Hi Chuck,

Thanks for the response

"I see two reasons for not drilling the holes at least until the gap is closed, if not later after the glue has set. The first reason is as you mentioned - the holes won't line up well. If the pinblock is tilted forward to begin with, and you drill your hole perpendicular to the plate, the drill bit is going to follow that line as it goes through the back assembly. When you begin to close the gap, the orientation of the front part of the hole (through the pinblock) and the back part of the hole (through the back assembly) is going to change, so that it's no longer a straight line. It's going to end up with the back part of the hole tilted up from the front part. If you've inserted your threaded rod right after drilling, it's going to bind and prevent the gap from closing. Does that make sense?

Secondly, the 1/2" drill produces lots of wood chips as the hole is drilled. The last thing you would want is for chips to get down in the gap before you try to close it.

To me, it seems safest to drill the holes last. Since the clamps I use are pretty much in the way while they're still in place, I don't do the drilling until the glue has cured and the clamps are removed. "

I do see the logic of drilling last. But, I think there are circumstances where it may make some sense to drill first, in such cases as the piano in this thread... where only the backposts have worked out of position, but the rest of the glue joints have held.

You make a very, very good point about wood chips. I think that in the future, if I must drill first, i will have a vacuum running as I drill to try to pick up the chips before they even fall into the crack. A very good point!

While we are on the subject of clamps, I was wondering if you, or anyone else here, had any firm opinions re the maximum amount of torque, foot-pounds or inch-pounds, that could safely be applied with the individual clamps, or individual bolts, without cracking the plate.

Thanks

The plate if going back to its previous condition is probably not crack..

Unless it decides to

Bill,

To my knowledge, it is mainly quick-set epoxy that is subject to creep. Slow-set forms more and better cross-links, and creeps much less.

Be that as it may, if all aforementioned adhesives (including epoxy) are subject to creep, then why use adhesive for a separated pinblock at all? Is it only an interim solution, to get the drilling done, and the bolts in place?

Isaac - I'm not sure about that. I'm no expert as to properties of various metals, but I don't believe cast iron has any "spring" to it. When it is deflected by the tension of the strings, and remains in that deflected position for a length of time, I don't sense that it necessarily wants to go back to its previous condition, as you say.

Could someone with more expertise comment on this? I haven't broken a plate myself with this repair, but I've seen a piano "repaired" by another technician where the plate was in fact cracked at the left strut. I was called in to see what I could do. Nothing at that point that I could see.

Again, as far as my write-up of the repair, the cautionary note concerning the risk of cracking is meant to provide some protection to the technician in case the worst happens. It's the same as warning a customer before a pitch-up that strings could potentially break. I would rather warn them and not have it happen, then not say anything until after the fact.

Joe, to answer your previous question, as long as the plate does return to its former orientation, and as long as you have a method of spreading out the pressure from the clamps (note picture in write up - I use scraps of pinblock material) I think you would have a hard time tightening your clamps by hand to reach a pressure that would break the plate. I don't have any way of measuring inch-pounds of pressure on my clamps, but I tighten them until the crank won't turn by hand any further. Chuck

Mark,
As you say, slow-set epoxies creep less, but they are still subject to some creep. The type of epoxy and the type of filler used will have an impact on its ability to resist creep. The surface area is also important. A high quality epoxy with a large surface area will have essentially no creep. A rough rule of thumb is the harder the epoxy sets, the more it will resist creep.

You can read more about epoxy/creep on West Systems' web site. They have an article about testing their products.

There are adhesives that do not creep... hide glue, plastic resin glue, polyurethane glues, and even super glues. Non of these adhesives are gap filling so you need to have a tight joint.

The other problem with pinblock separation repair is there is no way to properly clean the surfaces before applying the glue. Most of these separations are adhesive failures so the joint is full of old glue. The only glue that truly rebonds to itself is hide glue. But hide glue is not that easy to work with in someone's home.

I usually use Epoxy for this repair. I'll apply the epoxy, camp everything closed, drill out the old screw holes and insert new bolts. I try to get a bolt through each back post usually by adding extra bolts as needed.

Hi Isaac,

Though there has been some debate on this subject at PW before, I still believe that a plate can warp if it is kept out of its original position. Again, going back to when I was a student taking a grand rebuilding course, (and that's going way back LOL! So my memory may be flawed), I believe we were taught not to overtighten the screws when we initially install the plate. We were to let the plate settle a bit and then tighten the screws up a little at a time over several days, IF I remember I think that a bowed plate could possibly be persuaded back to it's original position if done gradually enough. We can "re-warp" it back to it's correct shape.

Unfortunately, I guess you are correct. You know you used too much force after the plate cracks. Or, the plate had an inherent hidden defect and the project was doomed from the start. I just wondered if there might be some sort of standardization as to optimal and maximum torque values. I guess this is one of those areas where you just have to use your own best judgment. Mine has been to observe how the nuts/washers are sinking into the wood on the back.

Chuck, thanks again for the advice. Many, many clamps; baby steps while tightening. It makes good sense!

Btw, this looks like you are doing another excellent professional presentation. Well written and great photography. Very classy!

Thanks,
-Joe

Bill,

Thanks for the detailed reply.



I've been wondering about the adhesion of other glues to hide glue residues. Reblitz, for one, warns us that PVA glues (carpenter's glue) make a jelly-like mess when applied over old hide glue.

And whether it's someone else's home or my own, my biggest concern with using hide glue would be its short open time. I'd hate to rush the clamping step.

Hello again, everyone. Based on comments made in this thread, I've done some revision on the write-up I've been working on, and would appreciate comments before I go to press with it. Check out here: "Repairing the Separated Back."

Please keep in mind that the intended audience is not the technician, but the technician's customer, to provide reassurance that the repair is needed and legitimate.

A couple of years ago I went to the dentist and was told that I needed a root canal. Not having had this procedure before, I was uneasy about the prospect. The dentist had a brochure to give me to take home. Reading it over at least took away the fear of the unknown. I wasn't looking forward to it, but I found I was much more relaxed about the idea knowing what to expect.

That, basically, is what this type of write-up is for--to take away the fear of the unknown for the owner of the piano. This is what the piano needs to have done, and this is how I will get it done.

Thanks in advance for any further suggestions before I finalize the copy to the write-up before publication. Chuck

Hi Chuck,

Great write-up.

Since this is for non-techs, my only suggestion would be to slightly expand upon the first paragraph somewhat... so the customers will understand why they need to have the separation repaired and help sell the job. Maybe just a little more on how the separation will affect things like tuning stability, etc. if left uncorrected. Possibly another sentence or so.

Of course, maybe you don't want to get into that much detail so as to just open the door for the tech to begin the conversation with the client?

Thanks for the suggestion, Joe. I'll try to do a bit more reworking of the opening paragraph or two and will post the revision when I'm done.

You are right about the importance of starting a conversation, however. When a customer feels he knows a bit about the topic at hand, I believe he is more open to talking about it. No one likes to feel completely stupid about a subject, so if you the technician can give them material to bring them up to speed,so to speak, it makes a conversation easier. Chuck

To Joe, Isaac, Bill, Ando and anyone else who has taken the time to look over my rough drafts - thanks. Here's the last (or close to it) version with some modification of the first page (according to your suggestions, Joe). I would welcome any last comments. The draft (Repairing the Separated Back - Final Revision) has been sent off to my editor for proofreading and hopefully it will be ready for distribution on the first of March.

In appreciation for your help, anyone who has pitched in with comments, or taken the trouble to read my material over, please accept my special invitation to receive a complimentary promo - your choice of topics. Thanks so much! Chuck Behm

Thank you for your very kind offer. I have decided to ask for the C/A promo.

Thanks Chuck!
Much appreciated.

-Joe

Joe - Check your email - I've sent the complimentary promo set over the topic you asked for. I hope you're able to put it to good use.

Thanks again for your suggestions (and the suggestions of others). When you're doing a technical write-up it's very helpful to get other opinions on the topic at hand - I appreciate the collective wisdom of everyone who posts here. I have my own methods of doing repairs, but for most repair jobs there are alternatives. It's helpful to hear about those alternatives so that I can do my write-up making an allowance for differing techniques.

If anyone else who has taken the time to read over the drafts of the separated back repair would like a complimentary promo set, here are the available topics. Pick out whichever one you would like. Thanks, Chuck

Beautifully done !

Thanks Chuck!
-Joe

So Chuck you have now Int recognizing as I forwarded it on the French PW forum

Piano owners are always amazed with the number of possible things on old pianos, and delighted to have a good global information on what can be done to repair.

But technicians of course also, thanks !

Comment from a friend : "blind" nut would be more nice looking (less easy to find may be, more expensive also)

Those long shiny screws for piano plates are expensive, I wonder if the American wood screws have different threading than European ones ?

Isaac - Thanks for the idea. I guess I've seen those in the past, but it never occured to me to consider making use of them for this repair. I would think from the back side in particular they would be useful. The big protruding bolts and nuts aren't particularly attractive when the back of the piano is exposed. I'm not sure going into the plate if they would work, but maybe so.

I'll check my local hardware store as to their availability. I'm sure I could order online as well, but whenever possible, I try to buy local.

Thanks again, and thanks for forwarding the post! Chuck

For the back I would try to make a deeper hole if possible, have the bolt embedded, I believe the front part is more where those large nuts and bolts could look a little surprising

when doing the job on site it may be a good idea to use a "martyr" (wooden plank) and not to make a hole in the wall behind the piano