apparatus and method for , in one continuous operation , receiving a slab sawn from a log , sensing the thickness of the slab and setting the apparatus to plane its upper and lower surfaces to produce a desired thickness slab which then is sawn into boards of desired width . the apparatus includes upper and lower planer heads , the upper of which is mounted on adjustable setworks for raising and lowering . at the infeed end of the apparatus a sensor determines the thickness of an entering slab and through control mechanism adjusts the space between the planer heads to plane the slab to a desired common board thickness which is the maximum available from the slab size . a bank of smooth cutting saws downstream from the planer heads saws the slab into smooth - sided boards .