Technical Stuff: From Logs to Lumber

Trees to lumber: Trees are one of the earth’s most abundant resources. It’s amazing to think of all the different species of trees, and their uses. What makes a tree suitable for a 2×4’s and what makes it suitable for instruments. In this post I’ll touch on the processing of trees to lumber suitable for guitars.

There are basically 3 types of grain:

Vertical Grain: this is lumber where the grain is vertical to the face of the board. The face usually resembles straight lines that run the length of the board.

Tangantal Grain: this is lumber where the grain (annual rings) are tangent to the face of the board. The face of the board usually has a swirled pattern with some straight lines.

Slash Grain: Also known as bastard grain, the board contains both qualities of vertical and tangantal grain.

Both grains can be achieved by intention, or as a byproduct of common saw techniques. If all logs were perfect, meaning even grain patterns in concentric circles finishing in a perfectly cylindrical tree, there most every log, if processed correctly could net lumber suitable for guitars, but that is not the case in the real world.

Trees are made up of many parts, but I’ll only bore you with 4 or 5.

First The Outer Bark: This is a protective layer on the outside. Not much use for this part in the music industry, so we move inward.

Second The Sapwood: This is the part of the tree that is the next youngest. It can be 5 or 50 years old. This section is usually lighter in color, and It is usually not used for guitars There are instances when the sapwood, lends an interesting contrast to the heartwood, and is used for backs or sides, it is almost always removed from top wood, unless log diameter is a factor.

Third The Heartwood: this is the part of the tree that is used primarily for instruments. It is where the color and character of the wood comes through.

Fourth The Pith: This is the center of the tree, and is the oldest part of the organism. This is usually the part of the tree that dies off first, and the place where rot begins to take hold.

Fifth The Annual Rings: These are made of 2 parts, early wood and late wood. The early wood grows fast in the warm part of the year, and is less dense. The late wood grows slower in the cold part of the year, and is what people normally associate with the growth rings of the tree. They are fine dark lines that form the circles that move outward to the edge of the tree. Both early and late wood makup one annual ring. The size or width of the ring can vary due to excessive rain or drought, and is usually associated with a 1 year span of time.

Your Garden Variety Log

There are a number of ways that both cuts of lumber can be achieved. The first is to plain saw the log. Simply the log is addressed from the top down. The saw blade slabs the log into boards and this process nets all three cuts of lumber in the most efficient way possible. the boards start out flatsawn (tangantal) on the top of the log, transitioning to slash, then vertical in the middle, and back to flat sawn at the bottom of the log.

The Plain Sawn Log

Second is to flat saw the entire log. Flat sawing is done by making a primary cut and then rotating the log 90 degrees and making another cut. The process is repeated till there is none of the log left to cut. This nets nearly 100% tangantal Lumber, and is somewhat efficient way to process the lumber.

The Flat Sawn Log

The Third way to cut lumber is to quarter saw the log. This is done by first cutting the log into (you guessed it) quarters. From there any number of steps can be taken. These are the least efficient ways to process the lumber, but net the best possible produce.

Example A: This quarter is held in place with the outside surface of the tree in the on the bottom. From here the quarter is run through vertical band saw cutting this piece of the pie into limber

Example B: This Quarter is addresses from one of the flat faces. After the first cut, the quarter is rotated 90 degrees and another cut is made. The piece is then rotated back to its original position, and the process repeats until all the lumber is yielded.

Example C: This technique is used to yield grain that is 100% vertical grain for guitar tops. The log is usually held in place by jaws at both ends, the grain is indexed using a laser and the first cut is made. Afterwards, a small wedge is cut away, so the grain can be re-indexed to achieve the vertical grain for the next cut.

Example D: This technique is similar to ex C. in the way that the log is addressed, but rather than cutting away the wedge and making flat lumber, the entire quarter is rotated at the apex, and the whole thing is cut into wedges. This technique is al little less wasteful, and make good stock for Violins and the like including arch to guitars.

The Quartered Log