Evaluating loss of machinability of spalted sugar maple

No current ASTM method exists for determining the machinability of spalted wood. Soft, punky areas can create obstacles for those who utilize spalted wood, and a repeatable test is needed to evaluate machinability. This study evaluated the machinability of 21 fungal combinations using a compression machine. Previous research was done on the 21 fungal combinations and can be found in Robinson et al. (2007). A cutting rotation test (lathe) was also run to produce visual representations of fungal degradation. The blade penetration test (amount of force required to drive a utility blade 0.635 cm in a radial surface of the wood) was then compared to the cutting rotation test to determine a lower limit of preferred machinability (153 lbs). Fungus combinations from previous research (Robinson et al. 2007) that showed the most internal spalting were assessed for their optimal incubation period. Blocks incubated with Bjerkandera adusta / Trametes versicolor for 8 weeks produced the maximum amount of spalting without lowering machinability ratings past the preferred lower limit (166.618 lbs). Blocks treated with Polyporus brumalis / Trametes versicolor and incubated for 10 weeks produced the maximum amount of spalting without sacrificing machinability (168.68 lbs).