Reamer bit with guide gauge protection function

A reamer bit with a guide gauge protection function is composed of a reducing coupling, a bit center pipe, a gauge protection waistband, a reaming cutter plate, a guide waistband, a guide cutting composite sheet, a gauge protection waistband rib support and a guide waistband rib support. The drill bit center pipe is sequentially provided with a guide cutting clad sheet, a chambering knife board and a reducing connector. A guiding waistband is arranged at the top end of the drill bit center pipe, and a gauge protection waistband is arranged in the middle. The guiding waistband and the drill bitcenter pipe are supported and fixed through a guiding waistband rib support, and the gauge protection waistband and the drill bit center pipe are supported and fixed through a gauge protection waistband rib support. The guide cutting composite sheet has the beneficial effects that in the chambering construction process, a new hole drilled by the guide cutting composite sheet can be kept coaxial with an original drilled h