In order to replace all plastic jacks with wooden ones, I asked someone to make them for me (he already has all the jigs to do this). I was somewhat surprised that I had to insist that the axle for the tongue should be drilled completely through and not stop halfway in the second leg of the jack.
Once the axle is drilled completely through you can easily remove/replace/repair the tongue.
I heard there are other makers who do not completely drill through the jack. Is there a good reason for this?
How did the ancients do it?
It’s usual, I believe. I do the same (though I am no authority in jack-making). This way the pin is firmly seated (nailed) in the not-drilled part of the fork and can’t exit from there even in the dryest weather when the holes enlarge.
Sure it’s very difficult to remove the tongue and the pin without breaking the tongue.
My jacks are drilled all the way through, and when I occasionally have to remove the tongue, it is still not easy to push the pin through with a piece of wire.
I dont see how it is possible to remove the pin if the hole doesnt go all the way through; but perhaps somebody can disclose the secret of how this is done.
on extracting one-ended tongue-pins from jacks:I remember this was discussed on the HPSCHD list, where suggestions amounted to discussing the best ways of removing a small amount of wood from the jack around the visible end of the pin until enough of this is exposed for a slender pliers to get purchase on it, then pull it slowly out.
With a belated happy new year to all, & thanks to Andrew for running the list!
What I do is place the jack in a vise, take a sewing needle and tap it into the wood at as precise a spot as I can estimate opposite the pin (use a straightedge/square to make a pencil mark). Often you can see a bulge where the tip of the pin is, so you don’t need to use the straightedge. The tip of the needle contacts the pin and drives it out the other side a bit. Then I grab the end with some flush cutting nippers and pull it out the rest of the way. I haven’t needed to do it often, but have always been successful.
Another interesting discussion.
Yes, drilling through tongue axle holes is a great idea to aid easy tongue removal in the future. (If the hole is of the right tolerance, it’s unlikely to give trouble with change of weather.) Of course, the tongue requires a larger diameter hole than that chosen for the jack body so it can pivot freely.
It’s rather tricky removing the tongue from jacks with blind axle holes. I had to overcome this in a non-destructive manner with my recent work on the 1775 Kirckman double. As part of its 1956 Dolmetsch restoration, the tongues of all four choirs were neatly broached square for the then-fashionable leather plectra. I decided to replace all 240 original tongues with reproduction holly & boxwood, and curved mortises as originally made for crow quill.
Of interest, the jacks holding the very few tongues which Dolmetsch had to replace after likely damaging them, had through axle holes with the original pin replaced with larger diameter—obviously easier work for them.
I temporarily removed the tongue staple, which enable to jack arms to be spread apart. I could then notch the brass axle pin using an X-acto knife, and edge out the pin fraction by fraction until enough was protruding to grab and remove. I numbered and retained the original tongues. The axle pins obviously had to be replaced.
I considered this option would give the best end result, rather than trying to plug the leathered tongues and remortise them appropriately.
Some detail of the instrument and its restoration here:
CBH Collection â Double-manual harpsichord, 1775 Kirckman
David Law’s website has information on drilling a small access notch to grab the submerged end of the pin:
He uses a hollow metal tube to which fine diamond dust is bonded. The hollow is of course a little bigger than the diameter of the axle pin.
I also confess that I find it odd to find axle holes not drilled all the way through. On the one full set of jacks I’ve made, I drilled them completely through and made them negligibly slimmer than my axle pins. The pins will come out with a little effort, but have never popped out on their own.
When it gets dry, then the wood shrinks. As a result the pin is even more fixed into the jack.
When I drill the diameter of the hole & axle are the same. In this way the axle fits snugly into the jack but isn’t loose either.
I use the metal point of an old compass (for drawing circles) to push the axle out. Works very well.
Uhm… Well, the other way round then: when it’s more humid.
But I’m not sure, humidity is a mean to actually close a hole - I use a drop of water to close the holes left on the soundboard by the bridge-positioning nails. So dryness should enlarge the hole. I’m puzzled.
Long-term shrinkage of the wood of the jack body is greatest along the tangential axis. Depending on the orientation of the grain of the wood, jacks may become measurably thinner, and hence looser, in the register slot with the passage of time.
A circular axle hole, unconstrained, in such a shrinking jack body would become correspondingly oval (smaller in the horizontal dimension than in the vertical), so the axle pin, which does not shrink, would become more tightly held by the surrounding wood. (Although wetting the wood surrounding a loose pin might grip it briefly, the effect would be temporary.)
When the jack body shrinks appreciably in width, the end(s) of the axle pin might protrude, so it’s necessary either to file the end(s) of the pin flush with the wood or, where only one end of the pin is exposed, alternatively to press the pin further into the wood of the jack (increasing the grip on the pin at the tip which is embedded in the wood).
This discussion indicates to me the advisability of drilling holes right through both sides of the jack in manufacture.
The ZHI jacks that I have are constructed in this way. On very rare occasions I have discovered a pin poking out, but not to the extent that it impedes the action. I just run a screwdriver shaft gently along the narrow edge of the jack, and the problem is fixed. Incidentally, the fruit wood that is normally used for jacks does not significantly change dimensions with humidity, and this stability is presumably the reason for its selection.
The advantage of being able to push the pin right through is surely obvious. I have had to do this, also rarely, when a metal jack spring needs to be bent back into shape. The suggestion of using a sewing needle with a flattened end to push the pin through is a good one, and I will try it next time.
I think somebody should speak in favour of ‘impaled’ tongues! I like them because you know that the axle will not work loose. At least some of the old makers liked them too - some Kirckman jacks that I worked on recently had them. In the rare event that you have to replace a tongue (which I had to with a few of the Kirckmans) you can cut the axle between the tongue and the side of the fork from where it was put in, with a piercing saw with a very fine blade. Then the tongue can be worked out by bending the remains of the axle and slightly forcing the fork apart. It’s a little bit brutal but it works. Removing the staple would make it a bit easier.