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More About Workability

Cutting

For best results, use a power saw with little or no set and as much lead as possible. Adjust the blade to extend through the panel at least 1/2 inch. Cutting teeth should enter the face of MDO plywood. Backing the panel with scrap material and feeding it through slowly helps avoid chipping. Panels can also be die cut. Contact a manufacturer at right for more information.

Drilling

A high speed drill is recommended. If appearance of the back is important, panels should be backed with scrap material to avoid chipping as the drill breaks through. Drill at least 1/4 inch in from the panel edge.

Bending

Wood panels can be bent in a radius. The distance of the radii developed by bending the panels is dependent on its thickness, panel type and moisture content. It is easier to bend the panels parallel to the structural axis of the panel than across the grain. The higher the moisture content of the panels, the easier they are to bend. See APA Technical Topic Bending Plywood, Form TT-003, for additional information.

Fastening

The integrity of an assembly is frequently dependent upon the connections between the components. For maximum strength and stability, each joint requires a design based on the fastener type and the strength properties of the individual assembly components. Commonly used fasteners include nails, staples, bolts, screws and adhesives.

Nails and Staples

Withdrawal strengths for nails and staples depend on many variables including the density of the wood species, the depth of fastener penetration and the type of fastener. For more information see APA Technical Topics Recommended Design Values for Nail Withdrawal From APA Plywood and OSB, Form TT-039, and Nailhead Pull-Through Strength of Wood Structural Panels, Form TT-070.

In general, these variables increase fastener holding capability:

• Higher density wood species
• Deeper fastener penetration into the wood
• Larger diameter shanks of the fasteners
• Deformed fastener shanks

Fastener head pull-through is dependent on the head diameter, panel thickness and density. For information on pneumatic nails and staples, consult the International Staple, Nail and Tool Association's ICC Evaluation Service Report, ESR-1539.

Screws

Commonly, structural wood panels are attached to metal with self-drilling and/or self-tapping screws, depending on the thickness. It is important to specify the appropriate fastener length, thereby ensuring that the threaded portion of the shank will engage in the steel framing. The performance of the plywood/metal connection is dependent upon the strength properties of the plywood, the shear value of the screw and the withdrawal resistance between the screw head and the metal. See APA technical publications Fastener Loads for Plywood – Screws, Form E830, Screw Withdrawal from Panel Faces, Form TT-050, and Screw Withdrawal from APA-Trademarked OSB, Form TT-051, for additional information.

Bolts

The performance of wood panel and metal connections is dependent upon the compressive strength properties of the plywood and the tensile yield strength of the metal fastener. For specific information regarding the design of bolted connections of wood panels, see APA Technical Note Fastener Loads for Plywood Bolts, Form E825.

Adhesives

There are many adhesive types on the market with characteristics that lend themselves to different types of fabrication with wood panels. The choice of adhesive depends upon the needs of the production. A structural adhesive is expected to produce a rigid joint and therefore must supply both stiffness and strength to the assembly. The strength requirement is generally such that the adhesive must be as strong or stronger than the wood it bonds. Structural adhesives often require the mixing of two components and pressure and elevated temperatures to cure. A semi-structural adhesive may be assumed to supply stiffness only. Adhesives are characterized by assembly times and temperature required to cure them. More information about adhesives and wood panels can be found in APA Technical Note Structural Adhesives for Plywood-Lumber Assemblies, Form Y391.