WoodSkills Issue 02 - Page 48

Depending on the glue you use, there is a set time associated with each type or brand of glue. It is critical to have all the clamps in place within the recommended set time. This eliminates any issues with thick glue lines, gaps or incorrectly glued boards. The number of clamps necessary are seen below. The rough boards are 32 inches long and 6 inches in width. Many clamps are necessary in the glue-up. I use my strongest parallel clamps for this operation. Parallel clamps distribute equal pressure along their jaws and easily handle the heavy, thick boards.

An alternative to multiple clamps is to place cauls across the length or width of the laminations. Cauls spread clamping pressure uniformly along the surface of the wood, resulting in the need for fewer clamps. If using cauls, a common technique is to create a slight convex curve in the center of the caul. The convex area ensures that the middle of the caul exerts equivalent pressure as the outside edges when clamped. If you opt to use solid 8/4 lumber in the build, I recommend using boards with rift-sawn grain orientation. Rift-sawn boards exhibit less cupping, bowing and twisting characteristics than plain-sawn wood.

Rift-sawn boards exhibit less cupping, bowing and twisting characteristics than plain-sawn wood.

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Several clamps are used to clamp two large

boards forming the 2 inch thick jaw lamination

It is critical to accurately joint and plane the inside faces of two adjoining boards. Since these two faces are glued together to create a thicker board, the surfaces need to be seamless across both their width and length. The straightness of the planed surface is tested using an accurate straightedge. This ensures that the surface is flat from end to end, across the width, and diagonally. The final thickness of each jaw will be 1.75 inches. One board is jointed and thickness planed on two faces while the other board is dressed or jointed on one face. This allows the final glued up board to have a jointed face as a reference in bringing the final thickness down to 1.75-inches.

The 1.75-inch final thickness for each jaw is optimized to the length of the ACME-threaded screw. This thickness provides adequate strength and allows maximum open throat depth using the 8-inch-long ACME-threaded screws included in the Benchcrafted hardware kit. Clamping the individual boards together to form the jaws is an intense process. Once it is determined that the jointed surfaces are straight, true and gap free, the glue-up can begin. To save time, I have all necessary clamps close by.