UTILIZATION OF DOGWOOD AND PERSIMMON 
19 
not only shrinkage, but also considerable tendency to warp and twist 
in a block cut at an angle. 
Block cutting, like bolt trimming, requires the highest degree of 
skill. A careful block cutter turns out 300 to 400 good shuttle blocks 
in a 10-hour day, but only men who have had a number of years' 
experience can cut the best blocks with a minimum of waste. The 
many small defects, principally knots and rotten streaks, found in 
the wood, together with the smallness of the dogwood bolts, make it 
a difficult matter to cut blocks that will meet specifications. The sides 
of every No. 1 shuttle block must be absolutely free of defects. (Fig. 
13.) The top and bottom of a block may contain defects only if 
these occur in that part of the block which will be cut out when the 
Fig. 13. — The stages in converting a dogwood bolt into a shuttle block 
center of the block is removed and the ends are pointed. In dog- 
wood hidden bark and knots cause tremendous waste. 
The machinery used in the manufacture of shuttle blocks is very 
simple. It consists principally of circular saws, generally rotating 
parallel to one another on the same line-shaft. Electric power is 
most used, although steam, gasoline tractors, and even water power 
are employed. Figure 14 shows a layout for a shuttle-block mill. 
The building may be largely of the shed type where no flooring is 
required, as the bare ground soon becomes covered with sawdust, 
which keeps the footing dry and soft and warm in winter. Some 
very efficient shuttle-block mills are found in the most unpretentious 
buildings. 
