As we continue to move through the jack making process, you will notice, dear reader, how the jigs and methods have changed over time. Like everything else related to this project, it's taking me far too long to settle on final methods. For everything. Owen Daly said it best: "You really should have started with a kit." The ironic thing is that I did finally manage to acquire a Zuckerman kit (not a Z-box) five years into this build, but timing has never really been my thing, so here we are.
Rather than expound upon the design of jacks and their tongues, I'd rather just point you toward Grant O'Brien's excellent website and graphic that clearly illustrate the parts and pieces of Ruckers-style jacks. At Owen's suggestion, I adhered pretty slavishly to the dimensions detailed in O'Brien's graphic and was privileged to recently engage in a two-hour 1:1 master class with master builder Paul Irvin in his Portland workshop. Now, on to making some tongues.
As you can see from O'Brien's graphic, the tongues are a pivotal part of the jack (see how I did that?); they rest inside the tongue slots I cut with the 5mm table saw blade on dress pins that act as axles. On the way up to pluck the string, the plectrum pushes the tongue against the angled bottom of the slot, securing it for the pluck. On the way down, the plectrum slides around the string before the damper comes to rest on the string; otherwise, none of the strings plucked would stop sounding and, holy cow, what a cacophony that would be.
One thing I learned from Paul is that the jack bodies are not only planed at an angle from the top down on the sides, they are also planed on the front of the jack. This allows sufficient room for the plectrum to push the jack body away from the string when moving down and then resting securely back in place when the key returns to its original position. As you can see, I left these planing exercises out of the previous post, yet be assured - I will make them so before fixing the tongues into the bodies.
The first step in making tongues is to plane down some European steamed beech to 2mm in height. The quickest and easiest way for me to do this at this time is to use the CNC machine, wasting 10mm of material during every planing session.
This is not my preferred method due to the excessive amount of waste and I don't want to mess with running such thin material through the planer. My ultimate plan is to resaw the beech myself down to 1/4" and then use the CNC for the final flattening. This would save loads of material and, therefore, dollars, and the Tortuga is a frugal fellow indeed. But I digress.
The results are nice, yet it still rankles that so much material ended up in the dust bin.
I then cut the material on two sides against the grain at a 45-degree angle using a tiny Freud table saw blade that is diminutive in both diameter and width. Sadly, I seem to have not captured any photos of this precise, exacting work (it's neither terribly precise nor exacting). After cutting this angle at 45 degrees (it should also be noted that I raised the 5mm blade to cut the tongue slots into the jack bodies to result in a complementary 45-degree angle), which is not traditional. I then made another straight cut to produce the final blanks a little rich in both width and length.
But first, a short digression (rationalization?) about using a 45-degree angle for the cuts mentioned above. The desired outcome when cutting the tongue slots and tongues is to have them fit together in a way that produces a tongue that lies flat against the front and back of the jack. Because I didn't want to mess with setting up 30 degrees here, 60 degrees there, I made them both 45 - both quick blade settings. The result is the same - tongues that lie flat against the jack faces. I doubt anyone will measure the angle and call me on it, but, of course, now they will.
The safest way to cut small pieces like jack tongues it to use a crosscut sled. Fortunately, I had purchased an Incra sled a few years ago knowing I would one day use it for such cuts. The Incra miter gauge fits snugly into it (it can be used with or without the sled) and provides a stop/hold down when cutting super-thin and/or small material.
As you can see from the photo above, I often use "frog" tape as width markers when making such cuts. I also used a piece of scrap beech as a cover to prevent tearout when cutting the tongues. If such material is not used, the saw blade makes a terrible mess of the top of the cut. Another benefit is that an errant tongue doesn't shoot from the saw and stick into one's face or other sensitive bodypart. Safety first at Tortuga Early Instruments Worldwide Headquarters.
A well-known conundrum of tongue making is how to cleanly cut the v-grooves into them. Owen had suggested I use a thin saw to mark a center line and trim out the sides with a small chisel. Paul recommended I use a "veining tool" used by leatherworkers. Before combining their suggestions, I had devised my own hair-brained scheme that involved a gent's saw (a small back saw) and a triangular file. Unfortunately, it cost millions of dollars and thousands of lives before I realized it was a pretty crappy approach.
While the results were okay, they did not provide the clean, crisp cut I had observed in jacks made by Norm Purdy. It was also a helluva lotta work. This is where the combination of Owen's and Paul's recommendations became a reality. The first thing I did was to make a small guide cut into the tongue using the gent's saw. Then, I used the veining tool in the photo below. Since this was my first experience using the tool, it took a dozen or so to settle on the proper angle and I ended up completing each groove with just two clean swipes. So, the prep station and veining tool ended up looking something like this:
Once I got the grooves dialed in, it was time to turn our attention to drilling the tongue axle holes and dimensioning the tongues. I intentionally left the tongues a little rich so they would fit tightly into the tongue slots. Then, we fitted the drill press with another .6mm bit and drilled the holes. You can see my little block plane in the bench vise above - it's upside down so we can trim the tongues for their final fitting.
It's widely known by now that we've brought a 3D printer into Tortuga Early Instruments Worldwide Headquarters.
So...why not use it to create jigs for the project, right? In this case, I designed and made a jig that holds the tongues at a precise angle and position so we can punch them using the drill press. I ground down a micro screwdriver to act as the punch and, as Owen says, "Bob's your uncle!"
The nice thing about a 3D printer is it's easy to redesign and remake something if it doesn't work 100% on first use. I've already made changes to the jig to provide little fingers to secure the tongue when removing the punch, which is astonishingly difficult, by the way. At any rate, you can see the Secret Weapon (Conner McClure) hard at work punching tongues while I'm off doing some other menial task.
In the end, we were able to successfully make a jack that, by all indications, might actually work.
After the 1:1 with Paul Irvin, I still have some modifications to make to both the planing of the jack bodies, as well as the jig. In the case of the jig, I will end up with two - one for the 8' and one for the 4' ranks - because the plectrum punch holes will be in different locations on the tongue. More about this later.
This wraps up the 6-month catch-up session. I will not leave you hanging like this again - I promise (to the best of my abilities). Now, it's time to sit back, relax, and enjoy the holidays with some of the finer things in life (yeah, that's a Tortuga Early Instruments label on the bottle). And make some jacks.
Until next time...