Editor's Note: This article is excerpted from a previous edition of Wood & Wood Products. To read the article in its entirety, click here.

With the right equipment and properly prepared material, it is possible to achieve a joint suitable for edge gluing directly off a gang ripsaw, saving time, yield and material handling.

A glue joint finish can be defined as follows: Ripped strips must hold a width tolerance of ±0.005 inch throughout the length of the piece. Width tolerance is best measured with a digital caliper on nominal 12-inch intervals. The ripped strips should hold a straightness tolerance of ±0.015 inch in 8 feet of length. This tolerance does not include stress relieved in the material as a result of the ripping process. In addition, the ripped edge finish must not have any variance exceeding ±0.0025 inch, i.e., saw hatch marks, and must be perpendicular to the planed surface within a tolerance of ±0.0025 inch. This tolerance explains why thicker material is more difficult to maintain glue joint quality.

For successful glue joint production, it is critical that the gang ripsaw be in good condition and adjusted properly. Feed works must have a flat and true surface and the means for captivation — friction, spikes and knurling — must be suitable for proper material containment. Seasonal changes also can contribute to increased glue line failure rates, particularly in the spring and fall, due to moisture and material stress issues.

Source: Mereen-Johnson Machine Co. Visit Mereen-Johnson.com or call (888) 465-7297.

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