Guitar maker's notebook

Wood portraits -- tonewoods from around the planet

I've always been interested in wood.  I guess that's what got me into my career as a forester and tree geneticist.  Growing up in Canada, I was always doing something with wood, whether it be building a soap-box racer (nearly killed myself when it rolled!), door stops, my own desk, and no end of construction projects on the farm.  My university training taught me a lot about what wood is and how it's formed.  It really is amazing stuff and the fascination with its properties and variation has never ceased.

Now as a guitar builder, I get to use this natural material to make beautiful instruments.  For me, the beauty starts with the individual piece of wood.  I don't make any standard models of instruments -- every one is different -- and the design is usually influenced to a large degree by the wood that I, or my client, has chosen.

I'm always on the lookout for unique pieces that can be incorporated in an instrument, and I'll try to buy beautiful pieces when I find them.  Fortunately, there is a netwook of wood suppliers who cater to instrument makers and their need for properly processed woods for instruments.  Logs are sourced from all over the planet and the variation is astonishing.

Just as a teaser, I thought I would assemble a gallery of some of my outstanding "back and side" sets -- as I write, all of the pieces pictured here are available in my stocked inventory!

Starting in North America, this set of black walnut (Juglans nigra L.) is from the United States.  Black walnut is easily worked and I particularly like the wild figure in this set:

 Black walnut (double click picture for larger image)

Further south in Mexico, Ziricote (Cordia dodecandra) has unique colours and wonderful figure.  Check out his beautiful set:

 Ziricote (double click picture for larger image)

Travelling further to South America, you might expect to see some of the famous Brazilian rosewood (Dalbergia nigra), but that species is now endangered and movement across internationaly borders is tightly controlled, even for old inventory.  Fact is, I don't have any Brazilian in stock, and given its endangered status, I'm not looking for any.  Instead we have a close cousin, also found in Brazil, Venezuela and Bolivia, Amazon rosewood (D. spruceana).  Anatomically, D. spruceana is indistinguishable from D. nigra, but is slightly more dense and laboratory extracts with water fluoresce under UV light (Miller and Wiemann 2006).  This is a set I've been saving for a few years now:

 Amazon rosewood (double click picture for larger image)

The "true" rosewoods are the genus Dalberiga, but the name "rosewood" is applied to several other timber species.  One of these found in Bolivia and Brazil is Pau Ferro (Machaerium scleroxylum), also known by timber merchants as Santos or Bolivian Rosewood, Jaracandá and Morado.  While not a true rosewood, Machaerium is considered a very close relative to Dalbergia, and Pau Ferro has become valued by instrument makers as a good alternative.  Aside from its tonal qualities, it's also a good looker:

 Pau Ferro (double click picture for larger image)

Africa is another southern hemisphere region with a wealth of stunning woods.  Among the true rosewoods, we find several striking examples in Africa, but most are in short supply.  So-called Madagascar rosewood is often identified as Dalbergia baroni, but there are at least 3 other Dalbergia species coming from Madagascar and marketed under the name.  One thing that is certain is that Dalbergia from Madagascar has been under excessive harvest pressure from illegal trade for musical instruments, and legimate supplies now on the market are rather slim.  I only have one back and side set in stock, but it will make an extraordinarily beautiful instrument:

 Madagascar rosewood (double click picture for larger image)

 In the tropical areas of western Africa we find a large tree known as Limba or Korina (Terminalia superba).  The wood can be light coloured ("white limba") or with darker striping ("black limba").  Conservation programmes and establishment of plantations have been quite effective in managing the supply of this species, so hopefully we'll continue to see it used for instruments.  The figure can be quite dramatic, like the example below:

 Black limba (double click picture for larger image)

Again in western Africa we find several members of the genus Guibourtia that are sought after for instruments.  Ovangkol (Guibourtia ehie), also known as Shedua, grows in tropical rain forests and is highly regarded as a tonewood.  Its close relative Bubinga (Guibourtia demeisei) is perhaps the best known member of the genus, and is under heavy harvesting pressure in Cameroon and eleswhere.  It is known for its red colour and striking figure, such as this example:

  Bubinga "waterfall" figure (double click picture for larger image)

Moving to India, we find another hotspot for sought-after tonewood.  One of the best known is East Indian rosewood (Dalbergia latifolia), sometimes called Indian palisandre or black rosewood.  India has placed tight controls on harvesting, and most material now comes from plantations.  To my mind, this species probably represents the "best value" in tonewood -- it makes wonderful sounding instruments and is a good substitute for the now-endangered Brazilian rosewood - its South American relative that is often recognised as the "king of tonewood".  Whether the subtle grain and dark colour appeal is a matter of personal taste, but I have a good supply, such as this example:

 East Indian rosewood (double click picture for larger image)

India is also the origin for one of the most commonly cultivated tropical fruits, the common mango (Mangifera indica).  The species is cultivated throughout southern hemisphere.  Some trees have dark brown heartwood, producing dramatic figure, such as this example:

 Chocolate mango (double click picture for larger image)

The mango is also cultivated throughout southeast asia, which also has other members of the genus Mangifera.  These other species can also produce dramatic figure, often through the process known as "spalting" (colour produced by fungi).  This example from the Phillipines is likely Mangifera altissima:

 Curly spalted mango (double click picture for larger image)

Finally, our global tour of tonewoods brings us to Australasia.  Australia itself is bless with many tonewoods, but is perhaps best known for Tasmanian blackwood (Acacia melanoxylon), sometimes known as black wattle. A very close relative to Koa, the traditional tonewood for ukeleles from Hawaii, Tasmanian blackwood was made famous as a tonewood by the AUstralian guitar company "Maton".  Almost every builder in Australia will have some in stock.  I only have one set, but I think it's a cracker:

 Tasmanian blackwood (double click picture for larger image)

Another tonewood from Australia known for dramatic colouration is blackheart sassafras, where spalting an other colouraton of the heartwood is casued by fungii:

 Blackheart sassafras (double click picture for larger image)

And finally to New Zealand, and its iconic tree, the mighty Kauri (Agathis australis).  Some of these giants fell into swampland some 30,000 to 50,000 years ago, and are only just now being extracted from the ground and processed.  How cool is that?  So-called "Ancient Kauri" is known for is chatoyance and intriguing figure.  One rare and sought-after figure is known as "whitebait swimming in waves".  I have a couple of sets in stock from a particularly good billet, but they don't photograph very well in rough sanded form.  Howeverm the figure explodes when finely sanded and put under a gloss finish, such as this example:

   Ancient kauri (double click picture for larger image)

As you can see, the choices are tremendous.  The various colours and figures of these woods inspire many ideas for stunning, unique instruments.  Which portrait speaks to you?

 

What's in a name? A lot -- when it's inlaid on the guitar headstock!

The aesthetic attraction that people have to an artisanal instrument is as strong for non-players as it is for musicians.  When folks look at my guitars for the first time, they often ask “Where do you get that done?”, or “Do you have a machine that does that?”  More often than not, my answer is “I do that myself – by hand!”

Perhaps the feature that draws the most questions is my name, which is inlaid on the headstock of every guitar.  It’s my artist’s signature and an important design element of every guitar I make, but people are absolutely dumfounded by how it’s done!

 

This example is an inlay of Mother-of-Pearl into Indian Rosewood -- a classic combination and looks stunning under a lacquer finish.  How's it done?  Not really a secret, so I'll show you a photo series of the setps.

Here's my set-up for cutting out the letters from a 0.050 - 0.060" thick slab of shell:

 
Basically, I use nothing more than a fine "jeweller's saw", a "V-block" (or "bench pin") secured in a vice to hold the slab of shell, and a vacuum cleaner to suck away the shell dust (you really don't want that stuff in your lungs!).

The design starts as artwork on my computer that I can print out in whatever scale I need.  A copy is glued on top of the shell slab with thin cyanoacrylate glue (otherwise known as "superglue").  Then it's just a matter of cutting out the letters carefully with the jeweller's saw:

 

 

So, that's the letters cut, now what about the cavity for the inlay?  Again, I glue a copy of the artwork right on the headstock, and use a model-maker's Dremel tool in a router base to carefully rout out the cavity with a 1/32" bit.  The paper fuzzes up a bit, so after I've finished a first pass, I sand off the paper and clean up any edges so that the letters fit perfectly:

 
 

Now it's a matter of flooding the installed letters with thin cyanocrylate glue:

 

After the glue has set overnight, the surface can be levelled with a few swipes of sandpaper:

 
 

And that's all there is to it.  Not exactly rocket science, but it does require a bit of patience and a lot of care!  The MOP takes on an amazing depth under lacquer and the inlay becomes something of an eye-catcher on the finished instrument:

 

Hearing your instrument in the hands of a professional

I delivered the instrument pictured in the photo albums under "Andrew's OM" in October on a trip through Canada.  I was really pleased with this instrument and think it's my best work yet.

So, I was blown away when Andrew put it into the hands of Toronto guitarist Jeff Biggar (www.jeffbiggar.com) this past month, and made a recording of Andy McKee's "For My Father".  The video is extremely emotional for me, as my own father died just before Christmas.

Of course, I'm also blown away to hear my handiwork in the hands of a professional talent like Jeff -- it really is what makes instrument building so rewarding.

Andrew was the sound engineer and is largely responsible for capturing the sound of this instrument -- thank you Andrew!



The unseen luthier's art -- Brace yourself!

It's ironic that one of the most important elements of an acoustic guitar is a part that's rarely seen by the player -- the bracing.  Here's an example:

 

In an earlier post, I wrote about the plates and how the material is carefully selected and prepared to be light, stiff and responsive.  It seems a bit counterintuitive that we would then glue on other bits of wood to the inside surface.

Fact is, the plates, and particularly the top plate, are under enormous stress.  The steel strings are under high tension and attached to the bridge, located in the middle of the top plate.  Were it not for some carefully located structural elements, the top plate would fail.  One of the primary goals of bracing is to supply structural strength to support the bridge area, but in such a way that the bridge can transmit the string vibrations into the plate.  It's a balancing act.

There are a large number of bracing patterns used by guitar makers, but for steel string guitars many of them incormporate what's often called the "X brace".  As you might expect, the brace elements are crossed in a lap joint and resemble an "X".  The lower arms of the X cross under the bridge to help give structural support while retaining the ability for the bridge to rotate front to back, and thus "drive" the top.  Also under the bridge, you'll find a patch of thin hardwood, which provides structural support to bridge area, while also providing a solid surface where the balls on the ends of the strings can have direct contact with the top, without causing damage.

Above the soundhole, one will usually find a beefy transverse brace which stiffens up the area where the finger board is usually attached, preventing distortion of the upper bout when under tension.  Around the soundhole itself, you'll also find small braces or an extra layer of top material in the form of "donut" which provides to stiffness to the perimeter of the hole and some protection against cracking of the end-grain.

Other smaller, light braces are also usually located to provide additional stiffness to targeted areas of otherwise be unsupported.  These provide some protection against cracking along the grain of the plate, and their stiffness and location can be adjusted to affect the tone and balance of the sound.

Generally speaking, we want the braces to be stiff, but without adding excessive mass to the vibrating top plate.  When preparing the braces, the maker will usually orient the grain 90° to the surface of the plate, and will make the brace taller than it is wide, all to maximize stiffness of the brace, while minimizing mass.  The braces can be further "tuned" by removing material from areas and decreasing the height of the brace where strength is less important.  This is known as "scalloping".

All of the brace elements work together with the materials and design of guitar to give the instrument its individual sound.  What might seem a random pattern of sticks glued to the underside of the top has an enormous impact on the sound.  You can't see the guitar maker's skill in this department, but you sure can hear it in the finished product.

In the photo sequence below, I'll take you through the bracing of an OM-style instrument. 

 

I've glued a circular patch over the area under the soundhole, just a hair larger than the rosette, and I'm thicknessing the patch with a drum sander.

 

Here the sound hole "donut" and the soundhole itself have been cut out.  The other bracing elements are dressed to rough dimension, and then glued on to the underside of the top plate.  Here you see a clever contraption known as a "go-bar" deck, where dowels are used to clamp the elements as they're glued.

 

Once all the elements are glued in place, comes one of my favourite steps in building a guitar -- shaping and scalloping the braces.  My weapon of choice, a 1-inch chisel.  By carefully shaping and whittling, while periodically tapping the top to monitor changes in the top's responsiveness, the braces take shape slowly.

 

And this is the final result.  Almost a shame to hide it inside the guitar where no one will ever see it! 
 
 
 

"My guitar has an adjustable neck, but I can't get the action low!"

I wonder how many guitar technicians have heard that?  Worse still, how many clients come in AFTER they've broken or stripped the "adjuster"?  Truth is, very few acoustic guitars have adjustable necks, but almost ALL modern-day steel-string guitars have an adjustable "truss rod".  Believe me, NOT the same thing at all.

Guitar set-up was on my mind this week, as I did the final set-up on my "Gemini" guitars -- matching 6- and 12-string dreadnoughts -- see the Gemini photo album.  Personally, I never want to see one of my guitars come back with a damaged truss rod, so I thought I would blog a bit on the subject. 

"So, just how does someone get a "good action" on a guitar?"  To reiterate, you DON'T get it by cranking on that truss rod adjuster!!  Of course, I'm assuming that the guitar doesn't have any fret issues or other problems that could cause noises.  But even brand-new, high-end factory guitars in a music store will require some additional set up to play properly.

What is commonly referred to as "action" decribes the height of the strings above the fingerboard.  If they're too high, it takes more effort to press the string down to "fret the note" and the guitar is hard to play.  If they're too low, the strings will vibrate against frets and cause all manner of unpleasant noises.  The height of the strings is determined by the height of the nut slots at one end, and the bridge saddle at the other end -- turning the truss rod adjuster doesn't affect either of these!

"So what DOES the truss rod do, and why is it adjustable?"  The truss rod is embedded into length of the neck shaft and is used to fine-tune the straightness of the neck when it is under string tension.  The picture show a neck blank where I've routed a slot to receive the truss rod assembly that is sitting loose on top.  While the string tension will cause the neck to want to bend slightly, the truss can be adjusted to apply counteracting pressure.

 

"So, you adjust it so that the neck is perfectly stright, right?"  Well, in fact, no. A small amount of "relief" is required so that the "action" can be set low, without the strings vibrating against frets.  We generally check the truss rod setting with the strings tuned, and a capo placed on the first fret.  We then fret a string on the 12th or 14th fret, and observe the "relief" or gap between the string and the 6th or 7th fret.  If there's no gap, either the neck is too straight, or maybe even bent backwards!  We're looking for a 0.010 to 0.020" (0.25 to 0.5 mm) gap, depending on playing style -- about the thickness of a standard business card.  To decrease the gap, we turn the truss rod adjuster a little bit clockwise, to increase the counteracting pressure.  We ALWAYS measure the change, and if it doesn't change, we don't just keep cranking -- a stripped adjuster or broken truss rod is usually a very expensive repair!

 

"My neck relief is within spec, but the guitar is still hard to play!" With the neck relief adjusted, the technician will then measure the gap between the strings and the 1st fret, and the 12th fret.  These indicate how much the string slots in the nut need to be deepened (or filled!), and how much the bridge saddle needs to be raised or lowered.

The gap at the first fret should be around 0.010 to 0.020" (0.25 to 0.5 mm) -- again about the thickness of a business card, and the height above the 12th fret 0.060 to 0.090" (1.5 to 2.3 mm), depending again on playing style.  If the gaps are way off, the adjustments must be made to the nut and saddle in steps, as lowering the saddle, will also tighten the gap at the first fret.

 

"OK, my guitar is now really easy to play, but never seems to be in tune -- what's wrong?"  You may have noticed that saddle on an acoustic guitar is on a "slant".  The length of the high E string is shorter than the low E string.  We call this "compensation".  When we fret a note, the string is slightly stretched.  Compensation helps to adjust for the effect this stretch has on the pitch of the fretted note.  Guitar makers use various methods to figure out the average compensation across all strings, and build this into the slant of the saddle.  But, that alone is not perfect.

If you play the open harmonic at the 12th fret, and then play the fretted note, they should sound exactly the same -- I actually measure the pitch with an app on my iPhone.  If they don't, we say that the "intonation" must be adjusted -- effectively lengthening or shortening the string at the saddle to fine-tune the compensation.  I won't describe the method in detail, as it's not something a novice should attempt -- but if you really must do-it-yourself, drop me a line and I'll point you to a tutorial on the net.

After checking the intonation string-by-string, I ended up with my 12-string saddle with a bunch of guide marks, telling me where to file the "string-break" peak for each string:

  

I then removed the saddle, filed the break points, polished the saddle, and then reassembled the guitar.  You'll notice that the break points for the high octave strings on the 3rd and 4th pairs are at the leading edge of the saddle, and the lower pitch strings "break" over peaks toward the back edge.

  

Now this is 12-string that is easy to play -- AND plays in tune!

Guitar makers make plates

Well, at least that's what we call them.  The guitar top and back are often refered to by luthiers as "plates". Quarter-sawn boards are prefered, cut radially from pith to bark.  Very rarely is a plate made from a solid piece of wood -- this would have to come from a tree whose diameter is at least twice as big as the width of the guitar, as it's essential to avoid the pith (a very weak area of a board). Such boards are sometimes available from big, west coast North American conifers, like Douglas-fir and western redcedar, but more usually plates are made by joining at least two pieces together, to make up the width required.

For Andrew's OM, the material for the top and back was supplied as book-matched pairs.  The pair was made by resawing a single board into two thinner boards.  The first step in joining the plates is to figure out which edges will be joined, the edges closest to the tree's pith, or those closest to the bark.  For the Malaysian blackwood back, it was an obvious choice to orient the bark-side edges together, so that the light coloured "sapwood" formed a decorative figure.  The choice for the German spruce top was more subtle.  Even in a "master-grade" piece, one can usually find some tiny defect that is exposed when the piece was resawn.  The pieces will be joined so that any defects are outside the guitar outline, or perhaps oriented out-of-sight on the inside surface.  For Andrew's OM, the piece of spruce I started with was very high quality and large enough for a jumbo-sized guitar, so I had lots of latitude as to how to orient the joint.

The traditional way to make the centre joint in a top or back plate is to use a long plane and a "shooting board", which helps to keep the plane at 90°.  The maker must check the joint carefully to ensure that no light is visible when he holds the two pieces together.  I take a non-traditional approach and dress the edge with a router running against a VERY straight steel guide.

 

After jointing, glue is applied and the two pieces clamped.  The photos in the album show the jig I use, made from some straight pieces of wood, some wedge-shaped pieces, and rope.

  

With the plates joined, a few passes through the thickness sander cleans up the surface and brings them to uniform thickness.  At this point, we make a final choice of which surface will be outside, and use a sanding plane to ensure that this surface is very flat and free of any defects -- essentially ready for finish.

 

The top will have a rosette inlaid around the sound hole.  This is an interesting decorative touch, but is also an important structural element, discouraging the formation of cracks that might form at the edge of the soundhole.  For Andrew's OM, we've opted to make a 3-ring rosette with strips of black and white "purfling", and a centre ring of paua shell -- a type of abalone native to New Zealand.  A small router is used to cut out the rosette channels, the purfling glued in place with a Teflon spacer in the centre ring.  After the glue has set, the Teflon strip is pulled out and replaced with the strips of paua which are then flooded with "super glue".  When everything is set, the rings are scraped and sanded flush with the soundboard and, voilà, we have an inlaid rosette!

 

Thicknessing the plates is part of the luthier's art.  We don't want the back too heavy, so not too thick, but we want it to remain very stiff, so not too thin.  The guitar top is a critical part of the instrument and has huge effect on the sound volume and quality -- the stiffness profile of the top will ultimately determine how it drives soundwaves into the box when the vibrations of the plucked strings are transmitted through the bridge into the top plate. 

You'll note the growth rings in the top are oriented perpendicular to the surface -- quartersawn, as it's called in the timber trade. 

  
 
Each ring represents growth over a single year.  Wood scientists refer to the light and dark portions of the growth ring as "earlywood" and "latewood", respectively (also known as "spring-wood" and "summer-wood").  The earlywood is made up primarily of large-diameter, thin-walled fibres (tracheids), while the latewood fibres are small in diameter, thickwalled, and rich in "lignin".  This makes the latewood much more dense and stronger than the earlywood.  When a board is quartersawn, the latewood portions are oriented like floorjoists and give the plate great stiffness even though it is quite thin.  How thin?  Well, that depends on the luthier's assessment of each top as more material is removed.  By flexing the top and tapping it, the guitar maker can feel and hear when the top really begins to sing -- ya kinda have to get a feel for it.

(Note: see the photo album for additional pics!)

Selecting wood for Andrew's OM ...

My newest project is for a producer/engineer/musician based in Toronto.  It's a long way from New Zealand, but he's seen and played another of my guitars and fell in love with it.  And besides, he's my nephew, Andrew (you can see some of his work at Andrew's website ).  How could I say no?  I told him I was interested in the project only if it was a special instrument and if he was involved in the design from the start.

Andrew had some clear ideas on some aspects of the guitar.  He was definite that he wanted a smaller body-style like an "OM", and he was able to give me guidance on neck and scale dimensions.  But he was leaving it to me to figure out how to deliver the well-balanced tone he was looking for that would be equally responsive to fingerstyle and flat-pick strumming.

I suggested we go with a "German spruce" top -- very white and clean looking, but also quite stiff and responsive.  What luthiers call "German spruce" is more commonly known in forestry as Norway spruce, scientific name Picea abies.  Virtually all of the native spruce from Europe that is available to luthiers is Norway spruce, but many feel that the different environments in which the trees grow has an impact on the wood quality, so it is marketed according to the region where it grew: "German", "Italian", "Carpathian", "Alpine", or simply "Euro".

I didn't have any Norway spruce in stock, but was able to find Master-grade material at Allied Lutherie in California.  I suggested to Andrew that we also look at Allied to see if they had any back and side sets that struck his fancy -- Allied posts pictures of their more interesting sets on their website, so you can see the actual set you're ordering.  We settled on a set of Malaysian blackwood. 

Now, this is an interesting species. It's sold by Allied, and virtually every other luthier wood dealer, as "Diospyros ebonaceae".  Indeed, Diospyros is one of two recognised genera in the ebony-persimmon family, the Ebenaceae (note the slightly different spelling).  Diospyros has up to 500 species, many of them in Indomalaya.  As far as I can tell, there is no recognised species "ebonaceae", but no doubt this wood is one of the many species of Diospyros growing in Malaysia.

Anyway, back to Andrew's wood, the set he chose was pictured on the Allied site:

 

                                                                   (Photo: Allied Lutherie)

Pretty cool, huh?  We decided that the sapwood will be oriented toward the middle of the back, as shown in the photo, and replace the backstrip I normally inlay in that position.  The sapwood also is a good colour match to the Honduras mahogany (Swietenia macrophylla) that I've chosen from my stash for neck.  For the rest, we'll use Carpathian spruce (you guessed it, Norway spruce that grew in the Carpathian mountains) for the bracing, and the trim, bridge and fingerboard will be very black ebony (probably Diospyros ebenum or Ceylon ebony from Sri Lanka or India).

The wood is now all gathered up, as shown below, and we're ready to start!

 

Now, gotta get back to finishing the "twins".
 

Catching up with "Project Gemini"

I've currently got a couple of projects underway.  Today I posted a photo album documenting some of the work under "Project Gemini".  This is actually TWO guitars -- twins -- a 6-string and a 12-string.  These have been made as identical as possible, and many of the parts were even crafted from the same pieces of timber.  They are currently in the finishing stage, which is a somewhat prolonged affair as I wait for lacquer to cure.  It'll be another 4 weeks or so before these babies sing their first notes.

Meanwhile, I've just started another commission for a musician in Toronto that should be a rather special instrument when it's complete.  More about that in future postings!

The blog begins ...

I build guitars.  It's not my first profession -- I'm actually trained as a forester and tree geneticist, and have worked in that capacity on every continent of the planet -- but I've always been a wood worker and I've played the guitar for as long as I can remember.  So, lutherie, the building of stringed instruments, has been a developing interest over the last few years and is becoming a new career for me, one that I hope I can continue long after my retirement from science.

In this blog, I plan to feature some of my ongoing projects -- with narrative and photos -- and hope it might be of interest to guitar players looking for that special instrument.  For me, every project is unique, working toward a personal objective to craft something special or to provide a musician with his/her "dream" instrument.  I learn from every instrument I make, and I try to achieve a high standard of craftsmanship, while building instruments that are first-and-foremost designed to be played by discerning musicians.

So, please enjoy what you find on these pages and join me in this journey