established simultaneously in the drill stem without regard to the particulars of the standing wave this involves both the drill pipe and the drill collars 14 the drill collar 24 of the present disclosure is installed above the drill bit it can be only one drill collar or it can be mixed with several conventional thick wall cylindrical drill collars whether alone or with others the drill collar 24 is caused to wobble in the manner discussed this inevitably brings the drill collar into scuffing contact with the borehole the parallel square corners 32 and 34 are wobbled into contact with the borehole where scuffing occurs the scuff plates 44 will prevent abrasion which damages the drill collar more than that the cutters 46 will ream the borehole so that improved clearance is provided the cutter 46 is preferably a flat tungsten carbide body which is brazed or otherwise joined along one face it can be formed of tungsten carbide particles in a cobalt alloy matrix for hardness while yet being somewhat shock resistant if desired the cutting edge can be formed of tungsten carbide particles or it can be enhanced and protected with industrial grade diamonds again diamond particles.