Piano World Home Page Forums Our Most Popular Forums Piano Tuner-Technicians Forum Replacing Silk Threads for Butterfly Springs

Hi all - Possibly this topic has been dealt with before. If it has I'll look it up, but otherwise I would like some ideas. I'm replacing the entire set of silk threads on a grand action for the butterfly springs. I've dinked around with these before, but have never done an entire set. I'm interested in hearing from folks who have done this repair enough to have a set protocol that works well. In particular, a method of ensuring that the amount of thread used is exactly as it was originally. (What I've had trouble with in the past for the looped thread is getting the loop through the hole, then trying to glue the peg in place without changing the size of the loop.) I've already regulated the action and adjusted the springs, so I want the tension on the springs to hopefully remain the same. (It wasn't until the regulation was done that the owner decided to go ahead and replace the threads.) Here's what I'm looking to replace:

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and:

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Any suggestions you might have would be most appreciated! Thanks, Chuck

The second one is easy. It is just like replacing the loops on Yamaha hammer flanges. Cut the cord to length by wrapping it around a piece of cardboard whose width is the length of the string, and then cut the cord and cardboard in half. Then just glue the new cord where the old cord was originally.

For the first, I would never glue the pegs in. You use a round toothpick and just cram it in. That way you can get it out if you need to. Cut the cord as above, except leave about a half inch too much. That leaves a nice crease in the middle, which is useful. Put the loop through the hole, with the quarter inch ends sticking out. Fold the ends down out of the way and hold them in place as you put the toothpick in. Then trim the excess toothpick and cord with a sharp blade. Break the tip of the other end off, so you do not damage the cord.

Chuck,

make a jig to maintain the exact length of cord you want on the loop. Sometimes something as simple as a piece of dowel inserted through the loop will give you something to pull against while inserting the peg.

IOWs. Insert the loop leaving excess length to put tension on the loop after inserting the sizing jig. Insert the proper sized jig into the loop. Hold tension on the loop while inserting the peg, toothpick or whatever. After gluing remove the jig/dowel and your loop is the proper size.

BDB has the right of it, and Dale offers excellent advice.

I will only add that you can pre-cut all your lengths of cord before beginning. And you may need/want to clip the pointy end off the toothpicks before beginning. Often they are too long and protrude through the opening into the loop area. Clip them (and do that all at once, after you know your needed length) the same, too.

Like any repetive job, just look for ways to be efficient. Pick up a tool and use it more than once! You know the drill, sir.

Smiling,
I am,

When replacing the loop cords for jack or rep lever springs, I use a fine wire bent in such a way as to leave a larger gap once passed through the plug hole, thus having an aid to pass the cord through and pull through the hole making the loop. It is the same idea as the needle threading aids, just on a larger scale.

Consider whether removing the hammer or wippen rail will allow you to do the repairs without taking the wippens off the rail.

Hi Ed - Thanks for the suggestion, but it's too late to go that route. I've got every other wippen off and am in the process of scraping out the old cords from the channels. Saving the looped end for last. Actually, I don't think with these wippens I would be able to scrape out the cords without having the assembly secured in a vise. They are pretty well glued in. I've customized a miniature chisel for the job, but it still takes quite a bit of effort to free the old cord. I'm afraid if I tried to do this with the wippen in place, I would be breaking things.

Here's the chiseling in progress:

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And here's a shot of the chisel:

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Thanks for the suggestions, all. I hope to have the job finished by the end of the day. I've got a lot of good ideas now to make the job go more smoothly. Chuck

One thing I've learned over the years when working in the shop is that if a job seems difficult to do, you are either (1) using the wrong tool, or (2) leaving out some important step.

As I scraped away at these cords, I thought about what I was doing wrong. The tool, I was sure, was not the problem. Perhaps I was leaving out an important step. I thought about how key bushings are removed by stuffing the mortise with damp felt wedges. Maybe water would help, so I lined up a dozen wippens on the bench, and brushed on a bit of moisture:

[img:center][/img]

I let them sit for a couple of minutes, until the water seemed to be absorbed into the cords, then tried using the chisel on one. Voila! - It peeled out easily and all in one piece:

[img:center][/img]

I'm sure this is established procedure (or at least it should be), but if someone mentioned it, I overlooked it. Thanks again, all. Chuck

Considering that all the joints on old pianos were made with water soluble glue, it only stands to reason that moisture will be an aid in reversing the joint.

Vinegar works even better than water. Nice pictures Chuck!

60% alcohol... dry faster. I drill thru the hole to get the cord out.

Resurrecting an old thread. What's the best way to get the old toothpick wedges out? Olek said drill, but that seems unnecessarily destructive with the potential to put a new hole in the wrong place. I've pushed them out backwards with a center pin removal tool before, but I have to also repin the jack for that.
(Looking at an old baby grand with sentimental value and multiple broken cords.)

You might try using a slightly undersize piece of music wire with the working end filed with an angled point that is then sharpened on a diamond hone. Use a pin vice to work with it.

Ed, I read somewhere else about somebody using a little custom made "drill bit" like that, sharpened to a point and then ground flat on one side. Is that what you're talking about, or are you saying to use the pointy wire to push the toothpick out from the inside?

From what I can see the original holes seem to be more conical than cylindrical, with the smaller opening on the inside surface of the jack.

I had this very project come into my shop yesterday. I took pictures and a short video of my process but I am such a forum noob (more of a lurker than a poster) that I can figure out how to post pictures and videos without first uploading them to an external site and having to enter a link. Am I missing something obvious on how to do this? Is there a way to directly post pictures into a reply? I'm happy to share my process. Just need a little guidance on how to post it. Any help is appreciated!

There is a Piano Photo Gallery area further down in the list of areas, where you can upload photos. You can link to them in posts here.

Hint: if you want to embed the photos, you need the address of the photo itself, not the address of the post in the Piano Photo Gallery. You can get that address by control-clicking on Mac, or doing the equivalent on a PC.

Thanks for the direction, BDB! I’ll work on it tomorrow.

Wow, cool thank you, that would be great. I typically upload my photos to imgur and then embed them here. For videos I would do YouTube and embed here. But that's just me.