To solve the problem that differences in tree species routinely cause burrs and chips in processing dried lumbers with a precut machine.

In the precut machine, a code to identify the wood species (the kind of the raw material)is added to CAD data describing the data on the material, the position and the shape for processing. The CAD data are converted into the CAM data. Cutting is made using control specifications for cutting means appropriate for the wood species (feed speed, revolution of motor for cutting tool or both) in the following two ways. One way is that the processing machine has processing programs different in control specifications for cutting means for the same processing shapes in the number corresponding to the codes for wood species. The other is that the processing machine has variables to change processing speeds for the same processing shapes in the formats corresponding to wood species and the setting of a control specification for cutting means is made simultaneously with the selection of a processing shape.