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I have a 1923 Gulbransen player piano that I'm reconditioning. I enjoy working with my hands and this is learning experience. I know not to expect a return on my time or money, other than a sense of satisfaction while doing it.

https://www.pianoworld.com/forum/ubb.../1923_Gulbransen_Player.html#Post2271821

The bass bridge has one long continuous crack over more than 3/4 of the upper bridge pin holes.



I plan on replacing the bridge with the help of a friend who does wood working, assuming I can remove the existing. I considered recapping it, but the apron below is cracked in 3-4 places and there are gaps between the apron and spacer on each end, large enough I can work a putty knife between, but so far I haven't been able to separate the apron and spacer any further.





Any suggestions on how to remove the apron without damaging the sound board? I don't believe this piano was previously restored so it should be hide glue that is holding it together. If the apron will separate from the spacer then I assume moist heat would allow you to separate the bridge and apron. I did already remove the 3 wood capped screws from the back of the piano.

Not moist heat, in my opinion. Just a heat gun and a chisel. Moisture tends to deform the wood.

Try some impact with the chisel before adding the heat. Hide glue is brittle when dry. It may snap off.

When adding heat, go slow. Work the chisel between the pieces. Be careful not to start following the grain into one piece of wood. If that happens, start from a different spot.

Thank you Mark, I'll try the chisel first and then heat if necessary. Does the heat gun give you good control of what you're heating or is the sound board going to be warmed as well? The reason I ask is before your response I thought of warming some 1/2" square pieces of steel in the oven to maybe 150-200 degrees and then place one on the joint, rotating them out as they cooled. I didn't know what temperature though causes the hide glue to begin breaking down (or if that was a good idea or not)

I like your website btw.

Dan, that's a bit of a challenging situation you have there. Usually a bridge is not removed (in its entirety) unless there is an expectation of replacing the soundboard. Bridge removal, even for a seasoned professional, is very exacting and usually somewhat destructive work. They are often doweled, screwed, and glued to the soundboard. Your best option, unless you are intending a new sound board, is to remove the plate, take exacting measurements, downbearing, and make templates of the bridge and apron and cut (plane) it down to a point where bridge duplication work can take place. I would be extremely cautious at the use of any steam. Controlled steam may be useful in the right situation. If the bridge root (the mating surface of the bridge attached to the board) becomes warped or damaged it gets worse from there.

Good luck. Not the sort of work for the unseasoned.

I certainly don't want to replace the soundboard. Though it has cracks, I haven't found any spots where it's separated from the ribs and haven't noticed any buzzing when playing. I'd much rather repair this in whatever manner is recommended for someone new to this sort of work. I know the danger of getting too deep into something before you have the skills or tools to complete the task. My daily driver is a '55 Chevy that I did a frameoff restoration on, doing all the work myself. It's easy to bite off more than you can handle and then be overwhelmed was you realize what has to be done.

Sounds like recapping would be the better choice, but what about the multiple cracks in the apron and gaps between the apron & spacer? I've read about using epoxy, though it doesn't seem recommended on a large break like this.

TSP or vinegar (cut the joint lines with a sharp knife first to allow penetration) and careful chisel work, you should be able to remove it.

I have special angled chisels that will let you work around the plate, but they are expensive.

Be patient. Multiple applications of vinegar in small amounts. When you first start chiseling, notice the direction of the grain. If one side starts to lift the soundboard, go to the other side. Same as when planing wood. Running the plank one direction will be rougher than the other. You want to go "up the tree". If pieces of the soundboard do get left on the skirt, don't touch them, tape them up while you work on the cap. They will actually help lining up the skirt when you glue it back on.

If you do recap, make sure you get high quality quarter sawn hard rock maple or equivalent.

No hide glue does not soften with heat but with moisture (plus heat)

We use alcohol in the glue joint because it make some water go inside. Vinegar certainly, possibly adding alcohol will allow it to penetrate. it will damage the varnish.

After a few days moisture may have soften the glue, You nee to add regularely and use shims to open the glue joint as soon it is possible.

the plate need to be out, there are measurements to be taken before, it is not something that can be done with Reblitz in my opinion.

you can test to see if the bridge is well secured usually. If only a little unglued I would add new hide glue and press it tight. thin epoxy can flow anywhere under the bridge, not sure it will really glue, in any case pressing is necessary.

<probably just tapping on the bridge will tell you if the glue joint is good

Remove the screws from the back of the sounding board that secure the apron to the foot. The bridge body and apron might pull off due to the constant prying force of the downbearing. The apron can be repaired or replaced. Make a new body from pin block material. Make sure to make it tall enough for sufficient down bearing. Do not index the pin locations off the old bridge, Draw a thread from the hitch pin to the front (top) string termination and mark the bridge. Chances are that the OEM pin location was wrong that caused the failure.

Last night I was able to exploit the separation of the apron and spacer (is that called the skirt?) In this picture you can see the putty knife is now slightly past the first large crack. There is complete separation of the apron from here and to the left of the putty knife, which I left in place as a wedge.

[img]http://imgur.com/a/Zmvka#ACdTz9N[/img]

I decided to stop there, score the top of the seam, apply a small amount of vinegar using a q-tip and let it weaken the bond. Depending upon how that goes I may or may not mix some denatured alcohol with the vinegar.

I did previously remove the 3 wood capped screws from the back. One of which was behind a support column but I was able to get it out using a 90' screwdriver.

"Do not index the pin locations off the old bridge, Draw a thread from the hitch pin to the front (top) string termination and mark the bridge. Chances are that the OEM pin location was wrong that caused the failure."

I wondered about this after reading Reblitz section on recapping. It does seem that the upper bridge pins stabilized slightly to the right. His book talks about too much right bearing but I don't think he says how to measure it, just that taking it into account may later require you to correct some hammer positions.

Now that the apron or cantilever is separated, do the piano a favor and recycle it.
Build a new solid bridge body that attaches to the board in much the same way that the cantilever did. Just make it taller so that the new bridge height when finished will give slight positive off-set (bearing) to the strings.
The cantilever is useless and unnecessary.
This will also make the job a bit easier.

Hi Gene, thank you for the idea. Isn't that going to change the speaking length of the bass section though unless you change the mounting location off the foot on the sound board?

My concern on doing this (as well as other changes to the original design) is I have no background doing this sort of work. If I don't understand the reason behind making a change I don't see how I'd be able to implement it correctly, or account for unexpected results that might occur. While restoring the '55 Chevy truck that I drive, I spent a considerable amount of time correcting modifications that previous owners made who didn't understand the ramifications of doing such changes. While I'm doing this as a project to learn on, I want to minimize frustration and expenses.

If I can successfully recondition this piano then maybe I'll do another (or not depending on how this one goes) and be more open to innovative ideas.

I did find some good reading on cantilevered bass bridges here. I'll keep reading, thank you for the suggestion either way. http://www.pianoworld.com/forum/ubbthreads.php/topics/160067/1.html

Hey Dan
Before you try a new solid bridge body you might make a template, position it on the board to see if you can attach it from the underside using wood screws and buttons.
Then just position it so that you match the original speaking lengths.
You can band saw off the cap of the original for a pattern just to get you started and have something to help you keep orientated.
If you want you can download free scaling programs to help with understanding scale perameters then if you need to change the speaking lengths you can do it with some idea of what you are doing to the scale.

Hopefully you took rubbings of the bass section prior to taking strings off.

I took downbearing measurements as described in Reblitz, but not rubbings prior to string removal. Lots of pictures though. I thought the rubbings were taken after you remove the strings and bridge pins in order to either recap or replace?

What should I have done differently?

Your bearing measurements were likely zero or negative??
As for a rubbing - strings are out so cant capture that but you can capture the position of the bridge in relation to the hitch pins and tuning pins. You pulled out the bridge pins so just use a needle to poke holes through your paper pattern and into the bridge pin holes. This will help you keep the original location of the bridge.
If you do not change the location of the bridge then all you need to do is send first and last bass string of each section to get a duplicate set.
If you change bridge position it gets more complex.

My son and I followed the directions in Reblitz, though I wouldn't beat the farm on our accuracy. Best I can tell the bass bridge is zero or a little negative, the treble bridge was mostly zero but some slightly positive. The soundboard has several cracks, but I still can't find areas that have separated from the ribs.

For the rubbing with the strings on, is it on the bridge? If so do you push the paper down so the bridge pins poke thru?

Just started watching this video. Well done up to now.

http://www.youtube.com/watch?v=uQZeUYkD50A

With strings on, the paper should be large enough (and relatively thick and stiff) to cover the tuning pins, bridge and hitch pins and trimmed to fit between the struts that define the bass section.
The rubbing should capture the tuning pins, front termination, strings in regard to the windings and how much core wire is exposed between winding and termination or if there is a double winding, bridge pins, hitch pins.
It won't hurt to punch the bridge pins all the way through the paper but not really necessary. Just get a good mark on the paper so the string maker can make accurate use of it - and for you for positioning the new bridge accurately.

zero bearing is typical for an old piano like this but don't worry about it.
just keep it in mind when you plane the new bridge to its final height - if you give it any bearing at all, make it very little.

;
I use a file to rub on brige pins - I do not rub tuning pins (but pins or agrafes)

you can order strings without a rub by measuring 2 distances from the hitch pin. A & B = front pin and total lenght - many string makers accept that plus a few diameters to obtain a good set they compute themselves.)

obviously they need all lenghts ; but for diameters the first and last of each serial is enough , plus a few legth and diameters after the break .

If budget is a problem you can use the old bass strings after cleaning them.