Quartered Sawn Wood in Guitar Making

Quartered sawn wood In guitar making on many top end guitars, is of paramount importance for structure, sound,strength and aesthetics.

Quarter sawing is a type of cut in the rip-sawing of logs into lumber. The resulting lumber is called quarter sawn (quarter-sawn), quartered, and radially-sawn.

Quarter-sawn boards have greater stability of form and size with less cupping, shrinkage across the width, shake and splitting, and other good qualities. In some woods, the grain produces a decorative effect such as oak which shows a prominent ray fleck and Sapele Mahogany is likely to produce a ribbon figure

When boards are cut from a log they are usually rip cut along the length (axis) of the log. This can be done in three ways: plain-sawing (most common, also known as flat-sawn, bastard-sawn, through and through, and tangent-sawn), quarter-sawing (less common), or rift sawing (rare).

In flat-sawing the log is passed through the blade cutting off plank after plank without changing the orientation of the blade or log. The resulting planks have different annual ring orientations when viewed from the end. The relative angle that form the rings and the surface go from almost zero degrees in the external planks to almost ninety degrees at the core of the log.

Quarter sawing gets its name from the fact that the log is first quartered lengthwise, resulting in wedges with a right angle ending at approximately the centre of the original log. Each quarter is then cut separately by tipping it up on its point and sawing boards successively along the axis. That results in boards with the annual rings mostly perpendicular to the faces. Quarter sawing yields boards with straight striped grain lines, greater stability than flat sawn wood, and a distinctive ray and fleck figure. It also yields narrower boards, because the log is first quartered, which is more wasteful.

Quartersawn boards can also be produced by cutting a board from one flat face of the quarter, flipping the wedge onto the other flat face to cut the next board, and so on.

Quarter sawing is sometimes confused with the much less common "rift sawing. In quartersawn wood, only the centre board of the quarter-log is cut with the growth rings truly perpendicular to the surface of the board. The smaller boards cut from either side have grain increasingly skewed. Riftsawn wood has every board cut along a radius of the original log, so each board has a perpendicular grain, with the growth rings oriented at right angles to the surface of the board. However, since this produces a great deal of waste (in the form of wedge-shaped scraps from between the boards) rift-sawing is very seldom used. Quartersawn wood is thus seen as an acceptable compromise between economical but less-stable flatsawn wood (which, especially in oak, will often display the distinct "cathedral window" grain) and the expensively-wasteful rift sawn wood, which has the straightest grain and thus the greatest stability.

Quartersawn boards have two advantages: they are more resistant against warping with changes in moisture and, while shrinkage can occur, it is less troublesome.

In high-end string instruments, the neck and fretboards can be made from quartersawn wood since they must remain stable throughout the life of the instrument, to keep the tone as invariable as possible. In acoustic guitars, quartersawn wood is also often used for the sides which must be steam bent to produce compound curves and the soundboard. The soundboard particularly, is often made from quarted Spruce or Cedar to enable the best sound consistency and strength. The strength (flex) will be more along the length (with the grain) of the top, and the braces will support the width. (In violins,wedges are split from a specially selected log to ensure vertical annular rings).This is mainly for structural reasons, but also for the aesthetics of highly figured timbers being highlighted when sawn this way. On high-end acoustic, electric and bass guitars quartersawn wood is often used as the base material for the neck of the guitar, since this makes for a stronger and straighter neck which aids tuning and setup stability.

The second advantage of quartersawn wood is the decorative pattern on the board, although this depends on the timber species. Flat sawn wood (especially oak) will often display a prominent wavy grain (sometimes called a cathedral-window pattern) caused by the saw cutting at a tangent to a growth ring; since in quartersawn wood the saw cuts across the growth rings, the visible grain is much straighter; it is this evenness of the grain that gives quartersawn wood its greater stability.

The Sound Post in a Violin - How and Why

In a string instrument, the sound post is a small dowel inside the instrument under the treble end of the bridge, spanning the space between the top and back plates and held in place by friction. It serves as a structural support for an archtop instrument, transfers sound from the top plate to the back plate and alters the tone of the instrument by changing the vibrational modes of the plates.

Sound posts are used, in all members of the violin family, in some members of the viol family, in some arch top guitars and in other string instruments

The position of the sound post inside a violin is critical, and moving it by very small amounts, as little as 0.5mm or 0.25mm, or less, can make a big difference in the sound quality and loudness of an instrument. Specialized tools are used for standing up or moving a sound post. Often the pointed end of an S-shaped setter is sharpened with a file and left rough, to grip the post a bit better.

Sound post adjustment is as much art as science, depending on the ears, experience, structural sense, and sensitive touch of the luthier. The rough guidelines in the following section outline the effects of various moves, but the interaction of all the factors involved keeps it from being a simple process. Moving the sound post has very complex consequences on the sound. In the end, it is the ear of the person doing the adjusting that determines the desired location of the post.

There is a definite effect of position on the instrument. Moving the sound post towards the fingerboard tends to increase brilliance and loudness. Moving the sound post towards the tail piece decreases the loudness and adds a richness or hollowness to the tonal quality of the instrument. Moving it towards the outside of the instrument increases brightness and moving in towards the middle of the instrument increases the lower frequencies. There is very little room to move the post from side to side without fitting a new post, or shortening the existing one, since tension (how firmly the post is wedged between top and back) plays an important role in tone adjustment. Perfect wood-to-wood fit at both ends of the post is critical to getting the desired sound

Truss Rods in Guitars

A truss rod is inserted into a guitar to compensate for the bend on the neck caused by the tension of the strings, usually on steel string guitars. There are some makers of classical guitars, that insert truss rods to allow more control of the neck relief and action

When the truss rod is loosened, it allows the neck to bend slightly in response to the tension of the strings. Similarly, when tightened the truss rod straightens the neck by resisting the tension of the strings.

It is desirable for a guitar neck to have a slight relief in order that reasonably low action be achieved in the high fret board positions, while at the same time, the strings ring clearly in the low positions. A lower action in the high fret positions also allows for more accurate intonation to be achieved with less compensation at the bridge.

Relief achieved through the truss rod combines with the height of the bridge to affect the playability of the instrument. The two should be adjusted in tandem. Too much relief contributes to a neck that feels floppy, slow and lifeless, while too little will allow the strings to buzz on the frets. Relief can be measured as the distance between the string and the 7th fret while holding down the first and last fret. The amount of relief preferred by many guitar manufacturers for an electric guitar is about .007 inches (approx. 0.175mm) at the 7th fret.

Truss rods are required for instruments with steel (high tension) strings. Without a truss rod, the guitar's wooden neck would gradually warp (i.e. bend) beyond repair due to applied high tension. Such devices are not normally needed on instruments with lower tension strings, such as the classical guitar which uses nylon (previously catgut) strings.

Truss rods also allow the instrument neck to be made from less rigid materials, such as cheaper grade of wood, or man-made composites, without which the neck would not be able to properly handle the string tension. The neck can also be made thinner, which can improve playability. In fact, the possibility of selecting cheaper materials is specifically touted in the 1923 patent as an advantage of the truss rod. Prior to the introduction of truss rods, the neck would have been made of a very rigid wood, and relief was achieved by planing the fingerboard: more expensive material, and more demanding construction technique.

Truss rods are frequently made out of steel, though graphite and other materials are sometimes used.

The truss rod can be adjusted to compensate for expansion or contraction in the neck wood due to changes in humidity or temperature, or to compensate for changes in the tension of the strings (the thicker the guitar string, the higher its tension when tuned to correct pitch).

Usually, the truss rod of a brand-new instrument is adjusted by the manufacturer before sale. Normally, turning the truss rod's adjustment bolt clockwise tightens it, counteracting the tension of the strings and straightening the neck or creating a backward bow. Turning the bolt counter-clockwise loosens it, allowing string tension to act on the neck and creating a forward bow (higher string action).

Tone woods - Stradivarius trees: Searching for perfect musical wood

Here is an interesting article I read by John Laurenson of BBC news and thought it would be worth sharing......................

Switzerland is home to some of the best violin makers in the world. But how do they know which tree will make a top quality violin? A wander through the forest with a master tree picker gives an idea of the enormous experience and instinct required.

Just any tree will not do when combing a forest in Switzerland for the perfect musical wood - its age, the weather and even the position of the moon help to craft the warmest, fullest notes.

Lorenzo Pellegrini shook his head and walked away, knee-deep in snow. He was not going to waste his time on that tree. Too many branches. Branches mean knots in the wood. And knots in the wood spoil its resonance. Pellegrini is a tree picker. He will find you the spruce in 10,000 that is just right. He will find you the "Stradivarius tree".

"Lentement, lentement, lentement," he says. "Slowly, slowly, slowly". That's how violin trees should grow. "Up in these mountains, they grow so slowly sometimes they stop growing altogether. They just gather strength. There are trees up here that are a thousand years old," he says. His blue eyes are wide with wonderment. "Can you believe that?"

Pellegrini has been working the forest since he was nine. Growing up in Italy's Abruzzo mountains, he and his family would go deep into the woods each year, hours and hours from the nearest village, build a cabin to live in and stay there for eight months, cutting down trees, chopping up logs. "I used to give my leftover polenta to the wolves," he says.

When he was 30 he discovered the Risoud Forest and never wanted to leave. Now 83, he still climbs trees like a squirrel, and tends the forest as if it were his garden - weeding out the beech trees that would smother his precious spruces. "For the trees to grow slowly and regularly, you have to let them grow close together like the hair on your head," he says. "And there should not be too much water. The tree's heart should stay dry. That gives the best wood. Solid. Enormous resonance," he adds.

Pellegrini "gardens" the forest, as he puts it. But he gardens for people who will not be born for hundreds of years. So that there will be fine resonance spruce in the 24th Century. Once you have found the perfect tree, he says, you have to wait for the perfect day to cut it down. That day comes at the end of autumn when the sap has sunk back into the ground. When the moon is lowest on the horizon, and furthest from the Earth.

Because, apparently, the gravitational pull of the moon does not only tug the waters of the sea and make the tides, it tugs up the sap. On that day, the tree is as dry as it can be. A ceremony is organised with the other foresters. It is usually the youngest who has the honour of felling it.

Driving down to Le Brassus, a little mountain town near the forest that houses many of Switzerland's most prestigious watchmakers, Jean-Michel Capt points to a mountain shrouded in cloud. "They say that when you can see that peak, it is going to rain," he says and pauses, letting us voice a little enthusiasm. "And when you cannot, it is raining already."

Capt is a craftsman and inventor who uses the resonance wood Pellegrini finds to make fine guitars. In his workshop he shows me a strip of tonewood from a tree at least 350 years old. Its grain, its rings, are dead straight and close together.

Put your finger on one ring - that is the British Army going over the top at Ypres. On another, that is Louis XIV building Versailles. This one takes you right back to the Pilgrim Fathers. To demonstrate the wood's acoustic qualities, he takes out a little musical box. He winds it up and it tinkles.He places the tinkling box on that strip of wood and the tune suddenly fills the room. Not only much, much louder but warm and full.

Later we walk through the village to meet one of the many musicians of the Risoud Forest. By the side of a wood-burning fire, by a table he made from a giant spruce, David Guignard takes out his cello and plays a bit of Bach - no pun intended.Around here you would not be surprised to learn that people wear paper shirts and grate wood shavings on their spaghetti.

"My father was a forest warden and my grandfather built a cabin for us in the woods," he recollects. "So the best moments of my childhood were in the forest. I was happy to live at the foot of those trees." Guignard's music teacher taught him that wood is never quite dead.

It is always reacting to changes in temperature and humidity, always evolving.I listen to the crackle of the fire and the sound of cello strings making the wood sing. And think that I will never quite hear this music in the same way again.

Because around here, when you hear an instrument like this, you think of the snow and the wind and the cuckoos and the bees in those tall violin trees.

Humidity and the effects on your guitar

Manufacturers warn owners to control the humidity of the guitar's environment but many players are still either confused or ignorant to the challenges that can take place.

Wood is like a sponge, as it absorbs moisture it expands and as it gives off moisture is contracts.
When it expands, it has to go somewhere. This could lead to warping, twisting and in the case of a soundboard, especially flat tops, it could invert, in other words bend inwards, causing a change in your action and a whole lot of domino effects, like buzzing, going out of tune to mention a few, so, the wood in a guitar must be dry, but, not too dry.As a result manufacturers dry their wood to an optimum moisture content of about 6% - 8% and some are able keep their manufacturing facility at about 45% relative humidity. These conditions will result in a guitar that is stable under normal conditions. However, wood is still an organic material and susceptible to changes in climactic conditions and can adapt to various humidity conditions.In conditions of low humidity the wood will continue to lose moisture and shrink.Conversely it will gain moisture when conditions are damp and this will cause it to swell. The consequences can cause sometimes serious challenges.

The greatest danger is low humidity.Any part of the country where there is a high heat season (or where there are desert conditions) is likely to see low humidity. Another one is air-conditioning, as this can result in very dry air, ie low humidity

The principal danger from low humidity is cracks in the top. Soft woods like spruce are more prone to humidity problems than hardwoods, but there are exceptions. Backs and sides can also crack quite easily.Some guitar woods, such as Brazilian Rosewood, are more susceptible than others. Another likely problem is shrunken fingerboards, resulting in frets protruding from the edge of the board.

If you leave your guitar in a car for too long in the sun, the car can heat up to some serious temperatures, especially if it is a hot day. This will result in a very quick loss of moisture, the wood to dry out too quickly, causing shrinkage and at the weakest place can crack or split, making for a very difficult repair

So, low humidity can damage your guitar.How to prevent this? First, be aware of the humidity level where your guitar lives.Humidity gauges are available and these may not be accurate enough for scientific purposes but for the guitar player they are fine.The goal is to keep your home/guitar room at about 45% relative humidity.

If the humidity is too low, a room or home humidifier is one solution, but often not enough.In most winter climates at somewhere about 30% relative humidity the moisture in the air will condense on the windows and the room will not get more humid.At that point a guitar case humidifier is in order.There are a few options available.They should be checked regularly. If you want to keep the guitar hanging on a wall, then the humidifiers which cover the sound hole will be adequate. Case humidifiers also are an option for dry conditions. If your humidity is moderately low (25 -35%) one in-case humidifier will be enough.If you over humidify, then swelling of the wood will occur.

Even if precautions are taken, wood being what it is, still tends to sometimes do its own thing regardless of what you do.