Folding wood and Bending Minds

FOLDING WOOD & BENDING MINDS

A deeper dive into kerf cutting for the laser

By Lev Uzlaner, General Manager Trotec Laser Canada & Don Connell, Marketing Director Trotec Laser Canada

As woodworking has evolved over time, many woodworkers have incorporated the use of laser machines, especially for cutting and engraving. When using the machines for engraving, woodworkers can personalize projects, add logos, and create intricate patterns, while a more experienced user might engrave wood for inlay work. However, using a laser machine for cutting is not as straight forward.

LEFT AND RIGHT: Trotec Laser Kerf cutting

Lasers don’t commonly cut wood sheets thicker than 1”, and that would depend on the type of wood being used. For example, while a 400W laser can cut a 1” solid wood sheet in one pass it may not be able to go through cork material because of “vulcanization;” the process where the char of the burnt cork prevents the laser from further penetrating the material – usually due to the compression of the material itself. Halfinch cork is tough to get through with even three passes without massive charring effects.

However there are methods to get around some of these challenges. An alternative technique, called “kerf cutting,” is a process of cutting detailed line patterns in a specific sequence in order to manipulate a flat sheet of wood, which may not bend or be pliable, into a piece

Trotec Laser Kerf cutting

of wood that can bend and fold depending on the direction, amount and length of cut lines. For example, using a 12” x 24” sheet of solid maple wood, we might begin by cutting six vertical “major” lines in the centre of the sheet going from top to bottom. These “major” lines are composed of smaller “minor” lines, 0.5” - 1” in length, with a 0.25” space between them. It is essential that these minor lines be staggered during cutting, with the resulting pattern not unlike a brick wall. Here too, stability has been added through purposeful offsetting of each piece, thus preventing weak spots while allowing for much greater flexibility. Although simple, this very basic kerf-cut hinge will permit a wood sheet to fold completely in half. The way a flat sheet of wood can fold and bend doesn’t only depend on the type of line pattern cut into it, but on other factors such as: the thickness of the wood, the length and amount of each break between the minor dotted lines, as well as the distance between each of the major lines. The wood thickness will greatly affect the results, for example if the wood is quite thin like a 1/8”, fewer major lines are needed to get a bend. If the wood is ½” thick, for example, one would need a greater number of major lines to help the fold, otherwise the bend will get stuck only half way. The amount of minor lines is also important; too many will result in a very brittle fold that will likely break after the first try. Too few minor lines will not give a full fold or bend. Distance between major lines is also very important. If they are too close together the wood will break from brittleness, but too far apart will not produce a fold.

It is best to do a lot of trial-and-error with kerf cutting to get the right result. There is no one-size fits-all approach with kerf cutting because each project, material, and design will be different from the next. Whether a woodworker is creating a book cover with a simple bend, or a complex 3-D pattern for an interior design project, knowing the endgoal result will make the process run smoothly and allow the woodworker to produce the best product every time.

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