Thursday, March 25, 2010

Rib Fest!

Time to add a rib! Job one is to loosen the previous rib. The mold is waxed but some residue always sticks things together. I wiggle my palette knife to break things free. If I didn't, I wouldn't be able to remove the bowl without damage.
The lute I'm working on is modeled after an instrument from the shop of Paduan maker Wendilio Venere, 1592. It currently resides in the Accademia Filarmonica in Bologna.

I've scribed a line at a known distance from the bottom of the lute that corresponds with the maximum diameter of the bowl. This keeps the figure on the sequence-sawn ribs aligned, which in this case is some nice bird's-eye maple.
Fitting ribs is a bit of a trick. They are only 1.5mm thick, and the form twists a bit - it's not like an orange segment! So I'm bending things in an irregular curve through three axes.
Some modern lutes are made truly hemispherical in cross section, which would make things easier. The makers of old did not do this! They shaped the volume of air contained within the bowl to accentuate certain sound qualities, and so must I.

Bending takes place with this electrically heated iron. The ancients would have used a rod heated in a charcoal brazier. Carbon monoxide poisoning aside, it's nice to be able to control the degree of heat. Bending is a slow-and steady affair with frequent checks against the mold. Things have to be pretty accurate as any deviation makes achieving the proper bevel angle difficult.

Here's my trusty hand plane fitted upside-down in my planing board. Normally I'd have both hands supporting the rib as I take sweeping cuts from the widest point down to the smallest. The plane blade is set slightly askew to give me a choice of light, medium or heavy cuts. Wow. The angle on this shot makes my thumb look freakishly long.

When there's a large volume of material to remove, such as here at the very tip I'll use my block plane set to take a course shaving. I do need to be careful though, as grain in this bird's-eye is so convoluted that it tends to chip out something fierce, even when going with the grain.

Getting closer. When the joint fits tightly along it's length with only light finger pressure, I transfer a series of measurements from the mould to the rib to gauge the taper on the other side. This will take into account any additional width needed to accommodate the spacer I'm using here. I try to end up with a nice smooth taper that approximates a straight line, as this makes fitting the next rib easier.

Yes. I do go through a lot of masking tape. I apply lots of glue to make certain there's adequate wetting of the joint. Over the neck block area I'm using a clamp and some reinforced packing tape to ensure optimum pressure.

Tuesday, March 23, 2010


Say, what's that glowing box in the corner of the room?
It's actually a low tech kiln powered by a light bulb. Pretty toasty in there, 26 Celsius ( 78 Fahrenheit). Dry too, only 17% humidity.

Open up, and in the inviting orange glow we see a stack of spruce soundboards, waiting their turn. I've done some experimentation and have come to the conclusion that soundboards benefit from this treatment of extreme dryness for about a week. Now, these are "seasoned" boards that have been stored for a decade in normal shop temperatures and humidity (45% in my shop). The internal resins have been solidifying and undergoing chemical transformations and all that good stuff. When put through this treatment, they will diminish slightly when measured across the grain, and don't ever seem to go back to their previous dimension even when brought back to "normal" conditions. I think of this as a little extra insurance in the event that the instrument finds it's way to Arizona or Dubai.

Here's a sample of my raw material. This is very pale Sitka spuce harvested in northern B.C. Sitka seems to exhibit less rosy colouring the farther north it grows. This is nice timber, good and stiff, perfectly quarter sawn, reasonably even grain spacing etc. I must say I hold some contrary opinions regarding soundboard material. I feel luthiers sometimes get caught up in the romance of "boutique"quality wood. We're snobby, and unfortunately we can pass that along to the players. A great soundboard can exhibit some uneven grain, squiggles, colour, or other variations. I care about what the wood says to me musically. Is it stiff and resilient? Does it have a complex musical tone when I tap on it? Judging tonewood on its appearance makes about as much sense as judging a musician's ability on their eye color. I recall seeing a great Christie's catalog cover showing a Guarnieri violin with a big ol' pin knot right behind the bridge. That instrument is valued in the millions. In the same vein, a plastic pitcher from the dollar store will be nice and smooth, perfectly homogeneous and it'll hold water. Given the choice, I'll take the hand-thrown wood fired one with Shoji Hamada's fingerprints marring the surface, thank you.

Back to work.
I'm using what's known as a shooting board here. I've taped the two halves of the top back together in the same orientation they had when growing in the tree - "book matching". My trusty Veritas #5-1/2 junior jack plane makes quick work of straightening the edge for gluing. I try to get the joint to fall between two sets of winter growth lines for a uniform appearance.

Here's my gluing set-up. I have a nice flat melamine faced board with two rows of machine screws along each side. I run these in until the central edges to be glued are about 5/8" (15 mm) off the surface. While learning luthiery with David Freeman at Timeless Instruments we made use of wedges and rope to provide pressure. This works great when using Titebond or other slow curing aliphatic glue. I'm now using a slightly curved board and a couple of clamps. When using hot hide glue this allows me to get things wet, pressed flat, and clamped in seconds without fumbling for the rope.

I start planing things flat using cross-grain strokes. This produces scruffy little shavings. I then turn things sideways and plane with the grain to remove the bulk of the material. (It makes the nice wide curly shavings to enthrall children if one happens to be doing this at a woodworking show.) This is one operation that has become faster over the years! I seem to recall scratching away for the better part of a day on my first guitar top. With a sharp blade and a sense of purpose, I had this lute top thicknessed and scraped in about half an hour.
Lute faces usually don't have a "finish" as such, other than wax. Here's a nice shot of the shimmering surface the plane left behind, and you can see the "silk", the medullary rays which dance in the light like little jewels. For lovers of wood, it doesn't get much better than this.

Saturday, March 13, 2010

Mirror mirror on the wall...

While cleaning out my parent's basement I spied a nifty fish-eye mirror. It was mounted in a strange brass wire surround over an antique white enamelled backer. Inspiration hit and my course of action was clear.

I have a great reverence for the Flemish painter Jan Van Eyck. (Also his brother Hubert)
Van Eyck was at one time credited with the invention of oil painting. This is not likely to be the case but it's immaterial, really, when faced with the jaw-dropping maturity of his technique. It's just this side of supernatural.

The Arnolfini wedding portrait of 1434 is one of the most analyzed works in art history, dense with symbols and perfect for art history term papers. When confronted with van Eyck's paintings I find myself acknowledging a concept I can only describe as "infinity". The best artistic parallel I've found is in the music of Bach. It's a holistic, universal, timeless quality that dwarfs the maker, the viewer, and the concepts of place or time. A perfect blend of science and art and the sacred.

Tuesday, March 9, 2010

Making Pegs

I've been refining my peg-making process recently. Using the info from Robert Lundberg's lute construction book and observations from a presentation by luthier extrodinaire Grant Tomlinson I've come up with this little setup.

It's a Taig Lathe outfitted with a second tool post mounted directly behind the primary cutter. I disengaged the cross feed screw and played with the jibs until it slides back and forward with very little play. Tomlinson's setup incorporated a neat spring loaded action to push the cutter away from the work when released. I rely on muscle power. The template is a two-piece affair that lets me change head profiles without messing up the carefully calibrated 1:30 shaft taper.

Would I change anything? The tail center on the Taig isn't what it could be. I purchased the "live" center but found it incapable of applying enough pressure on work held with the drive center. So, I'm using the dead center which works fine except for having to give it a tap every few minutes to take up slack.

I've been very satisfied with dogwood as a peg material. It turns well, polishes nicely, and it's very dimensionally stable. I bought a large supply that was cut for use in producing shuttlecocks in the 60's. Nice pinky-tan color that could be mistaken for European pear.

Given the vast quantity of pegs needed to outfit some lutes, I've made room in my building schedule to turn least one every day and stockpiling them for use. I graduate them in three sizes.

I'm anxious that my pegs should retain some "hand-made" character. I touch up the transition points with a small diamond-point tool and add detailing without having a "reference piece" to look at. I'm aiming for a smooth organic shape that's easy on the fingers. Looking at some surviving historical examples and iconography, one wonders if players had any flesh left on their fretting fingers! To that end, I've decided to go with a radiused profile imparted by a small diameter drum sander, followed by a quick buff on a cotton wheel with some wax.