Fallback Weights Demystified

Operating in the dark was too risky on an instrument of this price, so I broke down and wrote to the author of the clavichord manual for further illumination on what carving and weighting the keys is all about. A response came within hours and I was able to forge ahead.

Placing a key on the balance board (aka, fulcrum), I then placed, or at times gently dropped, the appropriate coin-weight on the front of the key. Naturally, the key is going to act like you've depressed it (which you have) and it will stay depressed as long as the coin-weight stays on the key. Ideally, you want to lighten - carve away - enough off of the front of the key bottom so that when you drop that little weight on the key, the key will dip and then gently return just enough so that the tail (where the thumbnail is located) of the key falls back to just touch the balance board. What is needed is removing weight from the front of the key and then, in most cases, adding weight in the form of lead wire to the back end of the key.

While it is never addressed, roofing the keys, as I did, removed weight from the back end. In my unprofessional opinion, this then caused the front of my keys to be even heavier in relation to the tail end. As a result, I ended up lightening up the front ends quite a bit.

I bought a set of Forstner bits.

The 5/8" size was used to drill out a chunk of wood from the underside of the key. I knew this wasn't going to be enough, so I also took the smaller bits and drilled out additional wood in hopes it would do the trick. It did not.

Those extra little holes are my brilliant idea of maybe shortening the time and work needed to lighten the keys by drilling out smaller holes with the other sizes of Forstner bits. After all, I had to buy the whole set. Why not try to use them? Unfortunately, it still wasn't enough and I ended up carving away more.

If I read the manual correctly, the carving on the underside is almost like the decorative roofing I did on top. But there was no way that would remove enough weight. So I made an executive decision to lighten my white keys in a totally new and different way when the extra holes didn't provide enough lightening. I carved with the barrel sanders on my Dremel.

Of course, none of this carving/lightening shows when the keyboard is in place, but I still wanted an artsy look to it (because I know it's there). And I just have to do things my way and be different. On some keys, that half-moon carving extends a little bit beyond the notch (function unknown, although I suspect it has something to do with the manufacturing and cutting process of the keyboard). Still, all these efforts did not lighten the keys enough.

My lowest key was profoundly carved and still required four pieces of lead to achieve fallback. The manual stressed that metal shouldn't be substituted for proper lightening. A hobby saw was recommended for cutting away key weight, but saws are never my tool of choice. Hence, the Dremel. Every white key needed a minimum of two pieces of lead.  Many took three.

Several of my sharps did not need any lead at all and fell back perfectly with a little bit of lightening. There was no drilling with Forstner bits on the sharps. Lightening was achieved with the Dremel and with adding lead when needed. The carving as shown in the first picture below was more akin to the roofing I did up top. The next picture is a little more creative.

 

Seasoned clavichord builders are probably cringing at my creativity. Don't care. I like what I did.

Below is an example of perfect fallback. Notice that the coin-weight is on the key, and the tail has gently dipped back to just touch the board. There are three pieces of lead added to achieve this.

As for the lead, the manual never says which way to drill - vertically (on the underside) or horizontally. I elected to drill the 9/64" hole horizontally. Once upon a time, I think I saw a picture online somewhere and it made sense to me. This way I could drill clear through the key, lay the key on its side, insert the wire down through the hole, and then snip it off about 1/16" to 1/8" beyond the hole. This allowed me to pound the 1/8" lead wire into the hole, allowing it to expand and completely fill the hole. I used my came lead snips from my stained glass days to easily cut the lead. In one or two cases, I was short just a small amount of weight and drilled a half hole. Worked perfectly.

You would hope that the lead supplied in the kit would be enough to finish the job. And your hopes would be dashed.  The 24" supplied fell way short. Zuckermann sells lead wire to the tune of $19 a yard (plus shipping). Yah. Not gonna happen. Not when it sells for 99 cents a foot at RotoMetals (I don't need 36"). Even with $3.95 shipping, it was still way cheaper than Zuckermann (and who knows what they'd sock me for "shipping and handling").

So, I'm awaiting the extra lead so I can finish up the keyboard. With luck, it will arrive this week. The end is in sight, and I am sooo ready for this instrument to finally be done!