The Research and Development (R£D) team recognized early the need for mechaniza- 

 tion of fingerling and flake production. Different size classes of residue by geograph- 

 ical sections of the country suggested that the problem of reducing residues to finger- 

 ling chips be split for research assignment. The North Central Station pursued the 

 problem of chippping the smaller residues, while the Forest Products Laboratory sought 

 out equipment for chipping larger residues. 



Small Residue 



The North Central Station found that conventional chippers produced chips that 

 varied too much in length to make suitable fingerlings. This led to the invention of a 

 spiral head chipper (fig. 3) . Although this machine would cut 95 percent or more of the 

 pieces to the length set by the cutter, many exceeded the 1- by 1-inch cross section 

 required for fingerlings. A hammermill with the grates removed reduced the oversized 

 pieces to finger-sized particles in one pass. The structural flakeboard made from the 

 aspen and spruce had very good strength (Erickson 1976) . 



The similar problem of oversized fingerlings occurred when lodgepole pine, Douglas- 

 fir, and larch were chipped for this study. Hammermil ling was needed to reduce chips 

 to fingerling size. Redesigning the blades in the spiral head chipper may eliminate 

 the need for hammermil ling . 



Conventional drive-shaft-mounted strain-gaging methods were used to measure torque 

 over cutting time and hence specific horsepower requirements by species. The western 

 species chipped required slightly higher horsepowers than Michigan-cut wood based on 

 specific gravities (table 1), perhaps because of the low moisture content of the west- 

 ern wood. Power requirements, although a little higher than with conventional chippers, 



Figure 3. — Fingerling production using the spiral head chipper. 



5 



