logs, from which the highest quality veneer is normally cut, will certainly 
pay for itself in the reduction of waste. When bucking the logs into bolts, 
due attention should be given to taper, sweep, knots, and other defects, so 
that the veneer produced will be of the highest grade possible. In a study 
conducted by the Forest Products Laboratory- the importance of sweep on the 
final veneer yield, both in quantity and in quality, was analyzed. It was 
found that sweep was one of the more important controllable factors affecting- 
yields; its effect can be minimized by carefully selecting logs so as to 
provide the long bolts required from the straight logs and cutting the logs 
having excessive sweep into short bolts. Greater care should be used in the 
woods to eliminate excessive sweep by proper bucking practices. Solts should 
not be so long that an excessive amount of veneer will be lost in the form of 
end trimmings or in the spurring operation. 
The heat-conditioning of veneer bolts for cutting is a process that requires 
careful control to prevent excessive waste in the form of degrade. Over- 
heating of some species results in excessive end checking of the bolts a;*d in 
poorly cut veneer. Underheating may result in loose veneer that is not suit- 
able for a high-grade product. The practice of heating various species of 
wood and logs of different diameters together, on the same schedule and 
possibly in the same tank, will sometimes result in some avoidable degrade 
because of improper temperatures for some of the species and diameters. The 
practice of heating wood in log length instead of bolt length, as is commonly 
done in Europe and occasionally in this country, is one that can be used to 
reduce the amount of split veneer obtained because of end checks in the bolts. 
The part of the lathe operator in reducing waste in veneer and plywood manu- 
facture is a most important one. His technique in handling the lathe deter- 
mines to a large extent the use for which the veneer is suitable. Improper 
lathe settings may result in veneer that is too loose, too rough, or too 
variable in thickness to be used for high-quality products. The condition of 
the lathe — whether it is in proper working order or whether it is worn and 
subject to vibration — and the condition of the knife and nose bar are all 
critical items. 
In rotary cutting, a reduction in core diameter is often thought of as being 
a desirable method, of reducing waste. It is not so important, however, as 
it might at first appear. To cut to core diameters smaller than the conven- 
tional diameter requires the addition of special lathes having small spindles 
and the rehandling of partially cut bolts, and in addition wood cut from the 
central portions of logs is generally of low quality. Consequently, cutting 
the cores to small .diameters has not usually been found economically feasible. 
Where long lathes are used so that it is not practical to cut to a 6-inch 
core because of the deflection of the bolt in the lathe, some operators have 
nevertheless installed a shorter, lighter lathe, cut the long cores in half, 
and turned them down to smaller diameters on the small lathe. 
c 
-J. Harry Rich, "Effects of sweep in the bolt on rotary cut veneer yields," 
1944. 
Reoort No. R1666-4 -3- 
