Factors Affecting Saw Capacity

Sawing rates are limited by the capacity of the sawtooth gullet to chamber the sawdust. Overloading will cause a sharp increase in power consumption, less accurate sawing, erosion damage to the wood surfaces in the lower portion of the cut, more tearout of the bottom of the cut, and earlier splitting as the end of the cut is approached. Tapered or stepped cants were used experimentally to determine feeds at which loading occurs. At this point the product of bite and cutting depth gives the area sawn per tooth. In determining gullet area and sawing capacity, two previously ignored factors must be considered: 1) With a large bite (e.g. 1/4 inch) the effective gullet area may be reduced about 20 percent due to solid wood projecting into the gullet. 2) As the gullet begins to emerge from the wood, sawdust can escape as formed. This greatly increases saw capacity when sawing narrow faces with wide sawtooth spacing. Formulas are given for computing saw capacity using these two additional factors. The author concludes that for actual, saw capacities, consideration must be given to species characteristics and variation of spillage with bite.

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