Apparatus for obtaining ring-shaped cavities in the bottom of drilled holes made in any type of medium

Abstract From the Canadian patent

An apparatus for creating annular cavities in the bottom of drilled holes in any medium having a body an axle, within the body at one end and rotated by a conventional drill, a reamer secured to the axle at its other end an, inner part enveloping the axle and an outer part enveloping the inner part, both parts being eccentric and rotatable with respect to each other. Their respective eccentricities are such that when opposing each other in opposite directions, the axle is parallel to the outer part. Joint rotation of the parts causes the reamer to move in a planetary manner. The outer part may be held stationary or dragged along by the inner part for joint rotation. Channels are provided …