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The technology of circular saws involves the use of a tensioned steel circular plate, accurately machined to accept welded tips of hard metals, each forming a cutting edge. Most shaper, router and moulder cutterheads and band saw blades also have hard cutting tips. Each hard carbide tip is geometrically ground to efficiently and safely remove wood chips while leaving a surface that is free from defects. Although this sounds easy, the result — even with the best tooling — may not be a defect-free product. Why is this? The inconsistent factor in this example is the use of a natural material, wood.

MOISTURE MATTERS

Wood is a mixture of harder and softer regions, moisture contents, tension differences, grain directions, tri-directional planes and structural features. A very smart professor once told his class that most wood industry machining problems are from moisture. Most machining issues have a moisture-related component to them. Proper kiln drying of lumber is also one area that has disassociated itself from the manufacturers of furniture and millwork. This disassociation requires constant communication with customers to guarantee meeting their needs.

Once moisture consistency is controlled on incoming lumber, maintenance of moisture content in lumber requires climate controlled storage sheds. Open air sheds will allow moisture to return into the lumber. Wrapping and dead packing loads slow the transfer of moisture, especially into the core of the load. End and side areas are generally more exposed to moisture change. A controlled environment will maintain the humidity levels resulting in a zero moisture content change. A noncontrolled storage location will allow a change in moisture away from the required percentage. This change can happen quickly. With extreme conditions, a change of several percentage points is possible.

Equally important, the moisture gradient within the lumber changes as moisture re-enters. If properly dried, lumber has equal moisture content throughout its thickness. By adding moisture the exterior portions increase well before the interior of the board. This difference can have a profound effect on planing, gluing, sanding and finishing.