Grooved sheet material

Apparatus for preparing a grooved veneer plywood and hardboard sheet material, comprising:

• i. a plurality of groove-forming devices disposed in a row
• ii. means for causing relative feeding movement, normally to said row of devices, of a sheet of said material having provided in a major face thereof a plurality of first parallel grooves disposed in a first direction parallel to said row
• iii. a plurality of shifting means coupled one to each of said groove-forming devices and adapted to shift the respective groove-forming device into and out of operative engagement with said major face of said sheet material, and
• iv. control means connected to each of said plurality of shifting means and arranged to cause shifting of selected ones of said groove-forming devices into operative engagement with said sheet material and simultaneously to cause shifting of other selected ones of said groove-forming devices out of operative engagement with said sheet material, according to the relative position of the sheet material in the feeding direction,
• thereby to permit the forming in said major face of the material of a plurality of second parallel grooves disposed in a second direction normal to said first direction, at least one of said second grooves being intermittent and formed in a first series of alternately spaced lands of said major face, at least another of said second grooves being intermittent and formed in a second series of alternately spaced lands situated intermediate the lands of said first series of lands.