Measures and yields of products and residues 329 1 



Because log scales have been devised primarily for logs in lengths different from 

 the 53-inch and 103-inch lengths (termed bolts or blocks) common to the ply- 

 wood industry, and because rotary-peeled veneer is cut without kerf and thin 

 (compared to boards), the usual yield and overrun tables are not directly applica- 

 ble for veneer yield computation. 



Veneer yield by grade and width. — Current and proposed systems for 

 grading hardwood veneer and veneer logs are discussed in sections 12-6 and 12- 

 7 (see tables 12-3, 12-4) and in table 22-16. Yields of 1/6-inch, rotary-peeled 

 veneer by grade and tree diameter (or block diameter) are given in tables 12-5 

 through 12-10. Figures 12-46 and 12-47 show the yield of 1/28-inch-thick 

 veneer from three grades of yellow birch and sugar maple logs. 



Rotary-peeled veneer is normally clipped to standard widths of 54 or 27 

 inches when possible; narrower veneer is clipped to random widths. Fishtails 

 are pieces of veneer that are not constant width full length; they are either 

 salvaged as 4-foot-long veneers for center plys or chipped for pulp. 



Yield of veneer for Ys-inch plywood per board foot log scale. — A mill-run 

 sample of factory grade 3 Appalachian oak logs yielded 2.18 sq ft of yg-inch 

 panel per board foot of log input, Doyle scale, or 1 .50 sq ft of Vs-inch panel per 

 board foot of log input, International y4-inch scale (Craft 1970, 1971). The 8-1/ 

 2foot bolts with an average small-end diameter of 1 1 .7 inches totaled 3,567 bd ft 

 Doyle scale, or 4,933 bd ft International scale. They were processed through a 

 southern pine sheathing plywood plant. 



According to a nomograph (fig. 18-256) for predicting veneer yield from 8-1/ 

 2-foot bolts of various diameters, 14-inch bolts produce 3.4 sq ft of Ys-inch panel 

 per board foot Doyle scale while 9-inch bolts produce 4.7 sq ft. Figure 18-256 

 also gives yield per cubic foot of log input and per cord of log input. 



Theoretical veneer yield per bolt. — If bolts were perfect cylinders, the 

 lineal footage of veneer produced from each would be a function only of bolt and 

 core diameters and veneer thicknesses (table 27-114). 



Veneer recovery. — In general, veneer recovery is highest by rotary cutting, 

 less by flat slicing, and least by quarter-slicing (see sect. 18-23 subsection 

 VENEER YIELD). For crooked logs typical of pine-site hardwoods, yield can 

 be increased by peeling 4-foot bolts rather than 8-foot bolts (fig. 18-255). When 

 veneer-quality logs of northern red oak were sliced, 56.7 percent of the total log 

 volume ended as dry veneer (fig. 18-257). 



Volume in stacks of veneer. — Stacked veneer sometimes accumulates in 

 mills and must be inventoried in terms of equivalent yg-inch plywood. Accord- 

 ing to one southern pine mill, a 103-inch-long stack of 54-inch-wide, 1/8- or 

 1/ 10-inch- thick dry veneer contains enough veneer per inch of stack height 

 to make 55.9 sq ft of 3/8-inch plywood; a comparable figure for random-width 

 dry veneers is 44. 1 . 



