Abstract: An expanding assembly to be inserted into and set within a preformed hole having a cylindrical portion extending inwardly from a wall surface and having a conical portion flared at a predetermined angle and located at a predetermined distance from the wall surface, the anchor assembly having a stud bolt carrying a cone at its inner end and being tensionable in the hole to displace the cone in the conical hole portion toward the mouth of the hole, the assembly having a sleeve surrounding the stud bolt and extending through the cylindrical hole portion into the conical portion to contact the cone, the sleeve being slotted to provide expanding legs which are longer than the conical hole portion, and the cone being almost as large in diameter as the cylindrical portion and being flared at an angle which is somewhat greater than said predetermined angle of the conical hole portion.

Abstract: A rotary expansion tool for undercutting walls of a pre-existing cylindrical hole in which it is a snug fit, the tool having a hollow shaft with opposed longitudinal slots through its sides near its inner end; a push rod extending from a tool-drive coupling at the outer end of the shaft, non-rotatably into the shaft and terminating at a clevis near the opposed slots; the tool having cutter means attached by a pivot pin to the shaft and pivotable about the pin so that the cutter means can extend one of its longitudinal edges transversely outwardly through one slot to contact the walls of the hole, and can extend its opposite longitudinal edge into the other slot to stabilize the cutter; the clevis surrounding the cutter means and cooperating with diagonal slots therein to rotate the cutter means outwardly of the tool when the push rod is urged axially inwardly of the tool; and means for locating the position in the hole of the undercut with reference to the mouth of the hole.

Abstract: A rotary bit for drilling concrete and reinforced concrete having a hollow drill stem with a transversely disposed drilling face at its outer end, the face having annularly disposed sawtooth surfaces including abrupt step portions alternating with trailing portions extending from the apex of a step to the root of the succeeding step, the trailing portions having diamond chips thereon and comprising crushing and grinding surfaces for the cuttings, and being sloped radially outwardly and axially upwardly to displace particles toward the outer periphery of the bit, and the bit having particle escape channels up its side surface adjacent the leading edges of the step portions which have hardened cutter inserts.