Sunday, 26 July 2020

Building a 13 Course Lute, Start to Finish, 19: Making the Peg Box

Hello, and welcome back to my detailed documentation of how I build a 13 course lute.

If you've been following along, you'll know that I'm in the midst of varnishing this lute. However, while the whole pre-varnish and varnish process takes two or three weeks in total, it only takes up a couple of hours of my time every couple of days--which leaves me plenty of time to make the peg box (and some other stuff, which I'll tell you about in a later episode.) Because it's a 13 course lute, this will be a fairly complex thing, and will eventually include a chanterelle tuner and a bass rider. Those two features will be added to the peg box after it has been fitted to the neck. For today, I'll only talk about making the basic box. 

I make the peg box out of five pieces of pearwood: two strips for the cheeks, a block at the tip and the bottom, and a back plate. There are also ebony veneers on the front and back, though not on the sides of the cheeks.

I begin with the cheeks, first planing one side very flat with the low angle block plane in my planing box. (This side will be to the inside of the peg box.) I note the direction of runout in the piece--that is, the direction that planes the easiest--and mark it.  I want to arrange the two cheeks so that, when the peg box is complete, I will be able to plane the outside of the cheeks easily from the bottom of the peg box to the tip. (As you will eventually see, this is essential for fitting the pegbox accurately in its joint in the neck.) 

With the planing directions sorted out, I also know which surface will be to the bottom of the peg box. I use my shooting board and bench plane to shoot that bottom edge flat and perpendicular to the side.

I can then start fitting pieces together on a little building-board. This jig is just a piece of (flat) mdf, with the dimensions of the peg box marked out accurately. I've covered it with a piece of packing tape, to guard against the frame getting stuck to the jig when I glue up. (By the way, at this point the peg box cheeks are both a little over-wide, over-long, and over-tall.)

To make the bottom block (and the tip block, too), I use a little sliding bevel to get the angle I'll need on the sides of the blocks. Then I can mark out my material, cut it out on the band saw, and shape the piece with a disk sander very close to the final dimension.

I do the final shaping of the blocks at the bench with files. Clamping both cheeks to the bottom block, as shown here, helps me to see whether my pieces have flat, squared surfaces--the better to build a strong box. 

Just a word on grain orientation, for all the pieces so far. The cheeks are quarter sawn, showing the quarter to the outside of the peg box. The bottom block and top block are also quartered, but they show their end grain to the front and back of the peg box. This is for a couple of reasons. First, the bottom block, when it's fitted into the neck rebate, will match long grain to long grain with the neck, making for a stronger glued joint. Second, having the top and bottom blocks show long grain to the inside of the peg box makes them less liable to absorbing water, which is used to clean up dried glue after assembly. (If instead end grain were shown to the inside, the blocks would easily absorb water, swell, and crack, in very short order.)

This is the basic gluing set-up. I'll do the bottom block first, then the top: brush glue on the contact surfaces, slide into place, clamp down to the building-board, then across from cheek to cheek. I don't have a pic of the full glued-up thing, but perhaps you get the idea.

The result, next day. Note the extra-tall bottom and top blocks, to facilitate clamping. I can now set this aside, and prepare the back plate. 
The back plate is a piece of quarter-sawn pear that's a bit oversize in length and width.

The back plate will taper in thickness by about 1mm along its length. Overall final thickness--including veneer--will be about 4mm at the bottom to 3mm at the top. This means that at this point, I want the back plate to be about 3mm thick at the bottom, and 2 at the top.

You can labour away with a low angle block plane at the bench to achieve this taper, or you can use this handy little jig on the thickness sander: just a piece of 400 grit paper backed with layers of masking tape to create a piece that tapers 1mm in thickness over its length. (The thinner end is to the left, thicker to the right.)

The jig is easy to use--just tape it to the feed table, put your plate on top, and run it through the sander. However, you need to be sure to orient the back plate correctly: the thinner end (tip end) goes to the thicker end of the jig; the thicker end (bottom end) goes to the thinner end of the jig.
The only practical way to put this part together is to glue the veneer to the back plate first, before gluing to the peg box frame. Here's my setup, ready to glue: lots of clamps; the thicknessed ebony veneer and pear back plate, double-side taped to their respective sides of the gluing press. I warm both surfaces with the hair dryer, brush glue on both surfaces, then stick them together fast and get even clamping pressure in place.

By the way, for gluing the veneer and back plate together, I use hot hide glue into which I've mixed a little alum. This is to guard, as much as possible, against the back plate curling up as it dries, which is one of the small frustrations of using hide glue in instrument construction. (I discussed this issue, and the use of alum, in a little more detail in an earlier post in this series, Building a 13 Course Lute, Start to Finish, 6: the Rose.)

But no matter what precautions I take, the back plate will curl a little (from the sides), and there's not much I can do to stop it. The best thing I can do to thwart the process is get the back plate glued to the frame as soon as I can.

Step 1: Size the end grain on the bottom and tip blocks. This is to ensure the best possible adhesion between the blocks and the back plate. 

The technique I use to size these blocks is one that Grant Tomlinson taught me, and I think he learned it from Stephen Gottlieb when he apprenticed with him in the 1980s: cold size. Rather than brushing on hot size straight from the glue pot--which might be absorbed too quickly and swell and distort the blocks too much--I put a little bit of full strength glue in a small dish, add about the same amount of water from the water bath, stir around with my fingertip until the mixture cools, and then apply it to the surface with my fingertip. I apply this size once, wait a few minutes, then apply it again. I let it dry for an hour, and then I can get back to work on the piece.

'Cold size,' about to be mixed. I was sure I had mentioned this technique another time, earlier in this series or in another post on this blog, but I can't find it now. (If someone else knows where the reference might be, please let me know and I'll link to it.) I use cold size in at least one other place in building a lute, and that is on the top block, after it's been carved, in preparation for having lute ribs glued to it when I put together the back. I should have described it here, in the first post in this series.

But back to the task at hand. When the cold size is dried, I flatten the backside of the peg box frame one last time, on a sanding plate. I also scrape the pearwood side of the back plate, in preparation for gluing.

I'm afraid I don't have any pics of gluing the frame and back plate together--just the end result, shown here. As you can see, the back plate is a bit over-long and -wide compared to the frame. I should also say that I use the building board for a gluing caul to put this together, and use a couple of wooden cam clamps on the bottom block, one on the tip block, and many down each peg box cheek.

With the plate glued on, I can use my low-angle block plane to trim the excess of the back plate and take the peg box a little closer to its final dimensions. (I still leave a millimetre or two extra of width on each cheek; I'll do the final trimming when I fit the peg box into the neck rebate.)
I also use the low-angle block plane to take the peg box to its final depth (which tapers from the bottom to the tip.) I try to get this front surface very flat, in preparation for gluing the front veneers. (The LA block plane works very well for flattening the end grain of the bottom and tip blocks.)
Front veneers. I fit the sides first, and will glue one at a time. I clamp the piece on dry first, without glue, and try to place the veneer so that there's a very small overhang over the peg box cheek. You can see I've got three clamps on a plexiglass caul holding the veneer in place. The clamp on the right side of the picture is just there to hold the peg box securely on the building board.
I've got a bunch of plexiglass cauls for this job, and they're long enough to accommodate one, two, or three cam clamps. I clamp the entire veneer in place, then remove a couple of clamps from one end.

I can lift the flexible veneer, and get glue between it and the cheek, then position the cauls, and clamp. Then I can remove the clamps and cauls from the other end of the veneer, lift that, get glue on the underside, and clamp it down.
This sort of clamping technique--getting the piece accurately clamped in place dry, then removing some of the clamps, applying glue, clamping, moving on to the next section--is something I do pretty often in this work (for instance, it works great when gluing the capping strip to the body, which may be viewed here, in the first instalment of this series.)  

I also need to glue veneer over the tip and bottom blocks; so first I'll give them a smear or two of cold size, then fit the veneer piece with--you guessed it--my low angle block plane, and a shooting board.
You can see in the photo above that there is some hardened glue squeeze out inside the peg box, both from when I glued on the back plate and when I glued on the front veneers. I will remove this by brushing cold water on it, letting it soak, and then scraping the softened glue out with a sharpened stick. I have to be careful to use water sparingly for this job; if I'm too generous with it, the back will swell, and probably warp, and likely crack. Best to work patiently, in this case.

At this point, the basic peg box is almost complete--there's one more job I need to do before I can be ready to cut the rebate in the neck and fit up, in preparation for fitting the treble and bass riders.

That job is: drilling the peg holes. I have a couple of photos of this operation, and I believe there to be a wealth of information about this process in them. Let me point out a few highlights.

Here we are at the drill press, pretty much ready to start drilling holes. I have a right angle holding jig to which I've clamped the peg box; I've also oriented the box along its centreline, so that the peg holes will be drilled perpendicular to it. On the back side of the jig, there's a big lead brick that somebody in the last 50 years or so left in the space in the building where I have my workshop. I use this brick to weight the jig down, so I may drill very accurate holes.
I would draw your attention to one other feature of the photo above, and that is all the bits and blocks of wood I have placed on the inside of the peg box. These are scrap pieces of jelutong (leftovers from lute mold making.) I've fitted two long strips up against the insides of both peg box cheeks, and then braced them against the cheeks with blocks. The strips and blocks provide backing for the drill bit; if there were no backing, the bit would break out and splinter the inside of the cheek.

A reverse shot, showing one other feature of this job: the marking out of the peg holes. I've drawn a line down the centre of the cheek, and marked the exact position of each peg hole along it. I've pricked each mark with an awl, and I'll drill pilot holes at each mark. I've also drawn a circle around every second peg hole, showing where I'll use a larger drill bit for the larger end of the peg. Uncircled marks will get a slightly smaller hole, for the smaller end of the peg.   
The completed box, ready to be fitted to the neck.
That's about it for this instalment, my friends. It's pretty straightforward, technical lute making; not too much art, I'd say, but a lot of craft. I'm saving the art for the next instalment when, at last, I will show you how I fit the peg box to the neck, and fit, glue, and carve the chanterelle tuner and bass rider. I may even describe gluing the peg box on. It promises to be a long, and possibly fascinating post. I hope you'll come back and join me for it!

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