Monday, 12 August 2019

Building a 13 Course Lute, Start to Finish (2)

Hello dear friends, here's the second installment of the ongoing series, in which I chronicle the building of a 13 course lute. As I explained at the outset, what I want to do with the series is to document the stages of construction in as much detail as reasonably possible. I'm presenting photos of each discrete task, and accompanying them with a one- or two-sentence explanation of the operation depicted.

This is not, strictly speaking, a how-to blog, though of course I do hope (and in fact I'm quite sure) that much can be gleaned from my depiction of the process. Sometimes an image of a maker doing some operation, or a photo of a particular jig or setup, will be enough to spark the imagination of an onlooker who can take that concept and make it work for them in their own building practice.

However, I think that this post especially, in which I describe working with the bowl and doing the initial alignment of the neck, may prompt a lot of questions. That's natural, because my work in this stage will really lay the foundations for the instrument's final action and playability. If I work well and carefully now, I'll eventually end up with an instrument that has a very comfortable neck size and shape, a well-curved fingerboard, and string heights that are nice and low--all of which go together to create a consummately playable instrument.

I may, therefore, pause once or twice in the chronicle to give a bit of background and explanation of what I'm up to. I don't want to purposely confuse anyone (though I'm sure I'll do it anyway...)

So let us begin, where we left off last time: with the completed bowl.

Seen here: poplar top block; honduras rosewood ribs; paper rib tapes; spruce counter-cap.

This photo, and the one below, show the bowl with the false belly fitted inside. This piece of carefully-shaped 1/4" pressed board will preserve the body outline securely throughout the building process.

I've spot-glued in a few places along the side ribs to keep the false belly in place. I've used weak glue size, so that it won't be too difficult to remove the false belly when I eventually need to do so.

Here I'm marking the various depths of the 'belly scoop' on the edge rib. I will then plane this scoop evenly into the edge rib on both the bass and treble side.

I've planed in the belly scoop, and you can see how it creates a smooth curve from the bottom end, to the middle of the bowl, to the top end. 

I mark the position of the front edge of the bridge by transferring it from my working drawing. Then I stretch a length of  black thread across the body at that point, and tape it securely in place with masking tape.

I also determine the body's centreline, and tape a length of the same thread to the bottom end of the body. 
A close-up view of the crossroads.

The centreline thread is long enough that I can stretch it across the  marked centreline on the top block, and eventually use it to align the neck. 

A view from the bottom end.

After drilling pilot holes, I screw a pair of plexiglass blocks into the top block. These blocks are crucial in setting the neck at the proper angle, and keeping it from slipping forward during gluing (after the neck is shaped and veneered).

Now I can start working with the honduras mahogany neck blank.  The first step is to flatten the top surface, which I do with a low-angle block plane. (This neck blank is built up of three pieces, which were offcuts from a plank which also yielded a number of single-piece neck blanks. I glued the pieces together a number of years ago; this neck will be as stable as a single-piece neck, and will use perfectly good material that would otherwise have gone to waste.)

This is my method of determining the neck cut-off angle: I lay a straightedge from the bridge across the top block, and a sliding bevel on top of that. 

I adjust the bevel so that it matches the angle of the top block face.

A brief aside about what I'm doing here: the thread I've stretched across the body represents the position of the front of the bridge, according to the plan view; it also represents the elevation of the bridge, in relation to the edge of the bowl. Referring to my side-view working drawing, and making some careful calculations involving the height of the first string at the bridge, the thickness of the soundboard, the thickness of the fingerboard, and other factors, I can determine the angle of the top surface of the neck in relation to this string. What you see in the photo is my straightedge resting on a spacer block of a precise thickness, which I've chosen because it will allow the straightedge to rest an exact distance below the thread (which I've calculated.) 

Once I've got the angle exactly right, I can then transfer it to the side of the neck blank...

And make the cutoff by adjusting the bandsaw table to the proper angle.

I then refine this angle with a low-angle block plane and, at the very last, a sanding block. This surface must be dead flat, and I check for flatness carefully with an engineer's square.

Holding the neck in place with the left hand, I bring in a straightedge to hold against the neck surface. This allows me to check the angle of the neck surface in relation to my bridge thread. 

I've stuck a bit of steel tape measure to the corner of the straightedge, so that I can see exactly how far below the cotton the straightedge sits. I will adjust the neck cutoff as needed with the low-angle block plane, files or sanding block, until the angle of the neck is exactly what I want.

When I've got the angle, I size the end-grain of the neck cutoff a number of times with hot diluted hide glue.

I also brush a few coats of size on the top block surface. I let both surfaces dry overnight, then re-fit the next morning, making sure one more time that the angle is exactly correct.

When I've re-fitted the neck yet again, I mark the position of the neck screw by pushing a shop-made awl through the screw hole in the top block.

There's my mark.

I have a good solid jig that I can clamp the neck to, to hold it upright while I drill a pilot hole.

Your humble narrator, in action, drilling the pilot hole for the neck screw.

Once the pilot's drilled, I can screw up the neck, and bring up the thread to mark the centreline.

And once I've done that, I can lay out the edges and centreline of the neck. (As you might notice here, the centreline of the body and that of the neck do not coincide, which is often the case with 13 course lutes.)

Here's me laying out the neck shape at the nut end. Note that I will prick along the inside line, subtracting the thickness of the neck veneer.

There's my neck profile at the nut end.

And here's my neck profile at the body-neck joint. Note that I've marked an inside line here too, to allow for the thickness of the veneer.

The first step in shaping the neck is to shape the long section only.

There's the long section: note how the line quickly re-curves as it comes away from from the body-neck joint, then flattens and tapers evenly out toward the nut end.

I shape the neck using, first, a spokeshave and small fingerplanes, then the low-angle block plane, then rasps and files, as you see here.

The re-curve in the long section, along with the change in cross-section profile from a near-semicircle at the body-neck joint to a very flattened profile at the nut end, make this neck a very complex shape to carve gracefully. This photo shows the nearly-finished shape.
As a final check, I screw the neck to the body to make sure I've left the correct space for the veneer.

And then, at the end of a long, long, long, long, long, long day, I sweep up.

I hope you've enjoyed this, the second installment of "The Tedium and the Triumph." So far much tedium, not too much triumph. But it does feel good to get a good shape on the neck, and I'm looking forward to veneering the neck next week, which I'll share in the next installment.

Sunday, 4 August 2019

Building a 13 Course Lute, Start to Finish (1)

Hi everyone--today I start a new project on The Lute's Progress: a complete chronicle of the building of a 13 course lute, from the very first to the very last steps, in as much detail as reasonably possible. What I have in mind is a series of photos taken along the way, each with a one-or two-sentence explanation of the stage or operation depicted. I want to stay away from long descriptions of how-to-do stuff; my aim is simply to document.

I have a few reasons for doing this. First, the person for whom I'm building the lute, Bob Eby, of Vernon, BC, Canada, asked if I would send him pictures of the process, and I said sure. I haven't documented my building very closely for a long time; it's not that I'm against it, but usually I'm too focussed on the task at hand, and don't think to grab the camera. With Bob's request, however, I now have a reason to make the camera part of the process. And photos are, these days, vanishingly cheap to produce and distribute, so creating a detailed chronicle won't break the bank.

There's one more reason I think it might be a good idea, and that's to show people, including my clients, aspiring makers, and otherwise interested bystanders, how many small, discrete, and necessary steps are involved in making a lute. There are a lot of glorious photos of finished lutes being shared by makers all over the world (myself included), and that's great, but sometimes I think there's a danger that the actual work involved gets forgotten or effaced. I hope to bring that sense of work back to the foreground with this series, and to remind us all that the amazing shot of the finished lute is the product of almost countless hours of real, difficult, at-times boring, and yet always highly-focussed work. "The Tedium and the Triumph" could well be an alternate title to the series.

A couple of things you should know before I kick off the chronicle: the lute is based on the body of the Tieffenbrucher archlute, C45 in the Vienna KHM, which I have designed as a 21 rib back, and the body will be built of Honduras Rosewood, with European Boxwood spacers. I'll address other questions of design and materials as they arise in the series.

If you have any questions about specific procedures depicted, please let me know in the comments section below, and I will consider discussing them in detail in posts separate from the series.

And so we begin!

Preparing to attach the poplar top block blank to the mold.
Laying out the shape of the top block on the poplar blank.
The rough top block profile cut on the band saw.
At this point the lute making elves showed up overnight, and finished carving the top block
 by hand. They forgot, however, to take any pictures of the process. Thanks a lot, guys!
(By the way, the mold on the right is for an 8 course lute
being built at the same time.)
Wood for the ribs and spacers: on the right, Honduras Rosewood rib blanks cut consecutively from 
a single large plank; on the left, sheets of European Boxwood for spacers.

Laying out and cutting out rib shapes. Stabilizing some small cracks with cyanoacrylate glue.

The complete rib set, cut close to final profiles. 
Using a hand scraper to take the ribs to their final thickness. (I've already taken the ribs to rough thickness in a thickness sander.)
Cutting boxwod strips to rough size for spacers. 
Sizing the spacers to their final dimension with the pull-through scraper.
The centre rib's bent and fitted.
Centre rib glued in place to the top block.
Fixing the centre rib in place on the mold, along its length.
Second rib and spacer bent, fitted, and ready for gluing. 
After a few ribs are glued on, the centre rib hold-downs are removed and I begin
 fitting and gluing ribs on both sides of the mold.
More ribs, trying to get the widths even at the front edge of the top block.
More ribs, trying to get the widths reasonably uniform as they pass
under the capping strip (which is marked on the mold.)
The outside rib is ready to glue on the bass side.
All the ribs are on; the back will be scraped, and
the bottom end shaped to receive the capping strip.
The capping strip is built up of numerous pieces of rosewood and boxwood.
The pieces are edge glued, then pressed between cauls overnight as the glue dries.
The built-up capping strip is cut out with jeweller's saw, then refined with a knife and files.
The capping strip, ready to be bent and fitted.
The capping strip is bent, positioned accurately, and dry-clamped
on the back--then the clamps are removed from one side.
The clamps (and shaped cauls that go with them) are laid out
in order, in preparation for gluing.
When the glue is dry on the capping strip, the back can be popped off the mold.
Note the hide glue remnants on the rib joints on the inside of the back.
I've carefully scraped the glue from the rib joints.

Another view of the back and mold, showing the capping strip.

Shaping the counter cap with a low-angle block plane.

Bending the counter cap with hot water and the bending iron.
The bent counter cap is clamped to a shaped caul and left to dry overnight.

Next morning: ready to glue paper reinforcing strips on the rib joints. Each paper strip
is soaked in hot hide glue and pressed into the joint, and the excess glue 
is cleared away with a wet cloth.

Almost half-done, and time for a little break to clean up a bit (it's a messy job.)

Gluing in the counter cap after the rib tapes are done (note the five
tapes across the ribs that help to prevent rib splitting.)

The reverse view of the counter cap glued in. 

Next day, the clamps and caul are removed. The bowl is essentially finished.

There, that's the first installment. Seems like a good place to end for today. Next time, working with the bowl and preparing to fit the neck. See you soon.