My customer gave the go ahead to work on the instrument, so I have dug a little more into it. The white jacks I suspected (with near certainty) were Zuckermann prototypes are indeed Zuckermann - once I looked closely with magnification, I noticed the name Zuckermann embossed across the top, with Pat Pending on the back. The tongues do pry out (using a tiny screwdriver to wedge it out from the back, screwdriver inserted in between the tongue's bottom and the body of the jack).
Not a successful prototype, and I am going to struggle to see if I can make it work. The spring, which is part of the body of the tongue, is half again as thick as on the modern Z jack (0.021" vs 0.014"), and a bit wider as well. So getting the jacks to fall (plectra to "escape") is a real challenge: the springs are FAR too strong. I've been experimenting with various things, including drilling and adding a lead weight (from my stock of original Z jacks, the straight-side kits) - which wasn't enough. I tried thinning a spring and also trimming its width.
I was hoping to do a fairly modest job (getting it all playable and fairly even) using the existing plectra (which are celcon, therefore recent, and hardly voiced at all). Now I discover that those were all inserted upside down (curving downwards rather than up), which, of course, contributes to the trouble of getting the plectra below the strings. It seems that if I reverse the plectra, minimize the distance the plectra extend under the string (when on), weaken the springs the maximum possible while ensuring they will barely touch the adjustment screw, I may be able to make a working instrument out of it.
I don't think Zuckermann was successful in patenting the jack - at least a patent search didn't show it (Zuckermann, harpsichord jack, harpsichord tongue, etc as search terms) - though there is a jack with the same principle of tongue, the difference being that the tongue is part of the jack, not removable.
Anyway, a bit of history uncovered. The instrument was made in Santa Fe in 1977, so I guess that is the time span for that jack. The later white jack with square bottom, that is more similar to the current jack, was from the early 1980s (at least the kit instrument I own which had such jacks dates from then). I guess the current brown one that is I-beam in cross section came around the mid to late 80s.
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Fred Sturm
University of New Mexico
fssturm@unm.edu http://fredsturm.net "When I smell a flower, I don't think about how it was cultivated. I like to listen to music the same way." -Federico Mompou
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Original Message:
Sent: 02-18-2015 23:20
From: Fred Sturm
Subject: Zuckermann jacks
I've had a uptick in harpsichord business the past few years, mostly from people resuscitating old instruments from the 70s and 80s, either kits or instruments made by "no-name" makers (people who didn't make very many instruments, and who often made very quirky design decisions). A few months ago, it was an instrument that had jacks that had started cracking and disintegrating, bad plastic, so all new jacks.
The two I have in the shop at the moment are somewhat interesting in their relationship to Zuckermann jacks. The first was built by a local Santa Fe builder in the 70s. He made most wooden things from scratch, but bought things like jacks. The jacks are nothing I have seen before, but I deduce they must be the early prototype of the jack Zuckermann uses today. They are white plastic with a square bottom, like some I am familiar with. They have the Zuckermann style tongue, in that the pivot and the spring are the same thing. What is different is the fact that they have a top adjustment screw, the tongue has mortises for both plectra and leather (slot and square), and the snap-in insertion into the jack body is triangular in shape. I'll post photos. Anyone else seen these? The problem, of course, is that replacement tongues are impossible, hence the real long term solution for the instrument is new jacks, a bit more expensive than this customer wants to go.
The other instrument is a venerable 5' straight side "Z-Box," the plywood kit out of the 50s through early 70s. In this case, somebody made an attempt to do the jack conversion. However, they couldn't figure out how to thread the tongue around the cross bar that limits the spring/pivot. So they inserted them all backward, shoved in plectra, and couldn't figure out why it didn't work. Hence they donated it to the local symphony, which wants it working so they can either sell it or find it a home. Not too bad, just remove tongue, remove plectrum, reinsert each the right way around, voice. Better than a lot of bollixed jobs I have run across. I'll post photos of that as well, along with photos showing how you SHOULD insert those tongues, how to thread them (it isn't intuitive).
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Fred Sturm
University of New Mexico
fssturm@unm.edu
http://fredsturm.net
"When I smell a flower, I don't think about how it was cultivated. I like to listen to music the same way." -Federico Mompou
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