In combination, a wood surface treating apparatus comprising an array of individual work stations arranged serially along and between infeed and outfeed ends of an endless conveyor, said combination further comprising:
- (a) frame means, said endless conveyor and array of work stations being supported upon said frame means;
- (b) said endless conveyor being adapted to receive a flow of workpieces at said infeed end and to firmly support and transport said flow of workpieces through said array of work stations for delivery to said outfeed end;
- (c) said array of work stations comprising at least first and second work stations, with each station comprising a working abrasive head and head elevation control means for adjustably positioning the work contacting surface of each abrasive head at a predetermined desired working distance from the opposed surface of said endless conveyor, with the working abrasive head of said first work station having a relatively coarse abrasive disposed thereon for abrasively removing that certain amount of stock from the exposed surface of each workpiece being transported by said conveyor until the workpiece is reduced to a predetermined first desired thickness dimension;
- (d) said second work station being disposed downstream from said first work station with a relatively fine abrasive disposed thereon for removal of a further amount of stock from each workpiece until reduced to a certain predetermined second desired thickness dimension;
- (e) a plurality of thickness monitors positioned in spaced relationship along said conveyor, each monitor having a thickness responsive detector means for generating a signal responsive to the thickness of each workpiece at spaced points along said endless conveyor, including an infeed thickness monitor at the infeed end of said conveyor, an outfeed thickness monitor at the outfeed end of said conveyor, and an intermediate thickness monitor positioned between each mutually adjacent pair of work stations for determining the thickness and extent of stock removal from each workpiece being transported from the upstream station of each pair of work stations;
- (f) a central processor in communication with each of said thickness monitors and said head elevation control means;
- (g) said central processor having means for receiving signals from each of said thickness monitors representing workpiece thickness and being adapted to compare the measured thickness dimension of each workpiece to a predetermined design thickness to thereby calculate a disparity value representing the difference between the measured thickness and the predetermined design thickness;
- and said central processor having responsive means for automatically transmitting a drive signal instructing said head elevation control means to selectively adjust the elevation of respective said abrasive heads relative to said endless conveyor in an amount substantially equal to said disparity value so as to continuously control said abrasive heads to obtain a workpiece thickness at each of a plurality of predetermined evaluation locations in said wood surface treating apparatus that is substantially equal to said predetermined design thickness at such evaluation locations.