Drill bit assembly for a directional percussion boring system

Abstract

The present disclosure describes various embodiments, as well as features and aspects thereof, of an improved drill bit assembly for a percussion boring system. More specifically, one non-limiting embodiment of an improved drill bit assembly for a percussion boring system comprises a bit and a chuck. The bit head comprises a slant face. The chuck comprises at least thirteen splines. This improved drill bit assembly is such that when the chuck is fully threaded onto the percussion boring system, and when the bit is detachably received by the chuck, the slant face of the bit is aligned to substantially within an average range of 0.00-27.70 arcseconds of an alignment reference point on the surface of the percussion boring system.

What is claimed is: 
     
         1 . A drill bit assembly for a percussion boring system, the drill bit assembly comprising:
 a bit comprising a head and a shank, the head comprising a slant face; and   a chuck comprising a first end, a second end and at least thirteen splines, the first end comprising a threaded coupling portion for detachably coupling the chuck to a percussion boring system, the second end configured to detachably receive the shank such that the shank slidably engages into the at least thirteen splines;   wherein, when the chuck is fully threaded onto the percussion boring system, and when the bit is detachably received by the chuck, the slant face is aligned to within 27.70 arcseconds of an alignment reference point on the surface of the percussion boring system.   
     
     
         2 . The drill bit assembly of  claim 1 , wherein the shank comprises at least two splines. 
     
     
         3 . The drill bit assembly of  claim 1 , wherein the shank comprises at least thirteen splines. 
     
     
         4 . The drill bit assembly of  claim 1 , wherein the slant face comprises a center point and the center point is aligned to within 27.70 arcseconds of the alignment reference point. 
     
     
         5 . The drill bit assembly of  claim 1 , wherein the alignment reference point on the surface of the percussion boring system is associated with a bent sub.