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Anyone repaired a broken key? Where was the break? How was it caused? My guess is that the slot at the balance rail pin is the weakest area. How did you make the repair?

I am shrinking a keyboard and want to narrow the keys. I expect that the key needs to be as strong as possible in the balance rail pin area.

James

I have repaired several that have broken at the balance rail.
If you can put the key back together at the exact break point then super glue will make a stronger joint than the key itself.
I use the more viscous type as it allows a bit more time, apply it and when the two parts fit perfect - hit it with the kicker.

Hi Chromatic,

You're right about the balance hole being the weak spot, especially on keys with a severe angle.

If you have the space in the keyboard to work with, clamp some veneer (cheap poplar is fine) on one or both sides, with the grain going the same direction as the key. Just pay attention to the balance hole. If you don't apply pressure, it's very easy to cause an elongated balance hole which causes "back chucking" of the key. Most pianists will feel that.

What do you mean by "shrinking" the keyboard?

"What do you mean by "shrinking" the keyboard?"

Well I am working on reducing the width of the keyboard from the 48 inch standard to around 42 inches(perhaps less). I think I can do this with the original keys by carefully sanding them for a closer spacing.

The fitting will be more difficult at the left and right sections as the key angles become more acute.

I was thinking that I could fit the area of the balance rail section into the neighboring key, leaving the slot and shoulders there at the original demension. There is some info on another thread regarding remaking the keyboard and hammer set to a smaller size for a grand. I am just tinkering with a landfill piano (upright) with the thought of making a keyboard for small hands. (My Granddaughter) Just a bit of off the wall tinkering.

My original question was seeking confirmation from techs as to the balance rail pin slot being the weakest area of the key.

James

You cannot do what you are planning. The front of the keys need to be smaller, while the back remains the same. After all, the top and bottom keys need to be displaced by 3 inches. Mere sanding will not work.

As much as I hate it when someone says "it can't be done", that's pretty much the case here, James. Or more accurately, it's going to be much easier to make / have made a new keyboard and keyframe.

Either you'll have to deal with large gaps between keys, or you'll have to somehow adjust the spread angles (new keyboard/cutting each key off and joining) and relocate the front and balance pins. You're in for a fair bit of geometry, shop time, and opportunity for destroying the instrument.

That's going to be a very time intensive / expensive six inches. Post pictures if you pull it off though, we'll all be interested!

when someone says "it can't be done",

You're in for a fair bit of geometry, shop time, and opportunity for destroying the instrument.


I am aware of the complexity of the project. I have the key bed from a junker that I have on a work table. Those keys near middle C will be the easiest and I don't think will require new keys. When I said sand, I didn't specify that I have more than a fingernail file to do the work with.

The first chore will be to fit a couple of keys. My thinking is that the area around the slot must remain as it is and the only place to have some space is to fit the (what will appear as a swell around the slot) into its neighbor key.

This is cut and paste with junk parts rather than cutting new wood. When I have the proof done, I can make a new set on a CNC router.

I am 66 and my time doesn't count. Just keeping my hands and brain engaged.

Thanks all
James

See if you can do it on paper or a computer screen before you commit yourself to removing wood.

Sounds like you have the tools and time to do it.

Since you have the CNC router available, you might consider fabricating hardwood "shoes" for the balance holes, then routing out a section in the keys for them and installing. This will help with the possibility of splitting.

On a computer screen---

I just bought Bob-Cad which is a drawing and machine control software program so as to do that myself, allowing me to take the drawing to the router (which is not mine).

But for now, I am using a pedestal sander and killing the junker stuff.

Also giving some thought to the possibility of miniturizing the balance pin thereby having a skinner slot. Nothing I have thought of seems to apply.

Can you be more expansive with the 'back chucking'. Does one hear something or feel something.

James