WoodSkills Issue 02 - Page 65

65

Introduction

When producing a curved section or item in wood there are several different approaches that can be considered – should the piece be shaped from solid wood, steam bent, or laminated from several layers of solid wood, plywood and/or veneer? Each method has its advantages and drawbacks but, when compared to the alternative methods available, lamination certainly has several points in its favor.

The strength of the section created with lamination is a definite plus to those wanting to create a slim profile without compromising on structural integrity. Carving or shaping a curve from solid wood means that at some point along the curve short grain will come into play and be required to take some of the load. This is less than ideal and, depending on the extremity of the curve, can be too weak to bear the requisite load or pressure without breaking. In contrast, creating the same section by bending and gluing several thin layers of solid or plywood to get the same effect results in a piece where the long grain runs continuously around the curve. This provides a surprising amount of strength for a relatively small thickness. The addition of layers of glue also adds strength to the curve. Simply put, unless the curve is relatively shallow, a lamination is stronger than solid.

“Aha”, I hear you say, “but solid wood can be steam bent to produce the same result!” This is true and in some cases, considering the style of the piece being made, can be the most appropriate method to use. But in many situations, style permitting, lamination still has the upper hand over steambending.

Where dimensional accuracy is of high importance, laminated sections are undeniably more predictable and accurate than steam bent sections. An amount of spring back is almost a certainty with steam bending and can be considerable in tighter radii or thicker sections of wood. This is difficult to predict accurately and also varies depending on species of wood, grain pattern and how the stock has been dried and processed. In comparison, although some laminations can experience a slight amount of spring back, this is dependent only on a few factors, such as thickness of layers and design of the former which can be calculated for. Steambending can also introduce compression folds into the inner curve of tighter bends and introduce some tension into the section which can affect the stability of the final piece.

The cost and material efficiency of choosing to laminate can also sway to the maker as follows. Facing a plywood section with veneer can allow the maker to use a burr, or unusual species without the expense of buying the same in solid. More importantly, it should be taken into consideration that veneer harvested from one tree can be used in tens or hundreds of projects as opposed to the same in solid. So if such a grain or species is used, veneer can be the more environmentally responsible way to include it.

The consistent repeatability of laminated sections is also a considerable advantage if you consider making more than one of the item or section. This makes it ideal for small batch production, or for use in a piece where symmetry is of the utmost importance.