API Contracting/Cornerstone Boring used a Michael Byrne 42” live swivel cutting head for a very tight and low ground cover auger bore in Paducah, KY. The bore crossed a highway and on-ramp with portions of the on ramp having only 2 feet of cover. It was completed using the Akkerman 240 Guided Bore Machine to pilot the initial bore path. That pilot was followed with a conventional auger bore machine and the Michael Byrne 42” live swivel cutting head.
The 42” swivel head uses a threaded coupling that is attached to the pilot bore tubes. The needle of the cutting head is inserted into the adapter coupling and seated against the face of the cutting head 3” male hex. The boring machine proceeds to bore in a typical auger bore method. The swivel cutting head pushes the pilot tubes out of the exit pit as the cutting head follows the path of the pilot tubes opening the bore to the desired 42” diameter. The cutting head is made with thrust bearings and can handle thrust and radial loading. Care must be used with this method of precision boring by letting the cutting teeth bore the hole and do the work. Putting too much thrust pressure on the head could damage the bearings.
API/ Cornerstone has performed numerous precision auger bores using the live swivel head and the Akkerman guided bore system. Underground work often runs into unforeseen obstacles, one of which is changing ground conditions. The live swivel lets you pull your cutting head and auger back to check the face of the bore. The tapered front needle of the swivel will let the head re-seat into the coupling attached to the pilot tubes and continue your bore.
