Large Bolts Drillco not only makes any length you want, we now make any diameter you want up to 6"Drillco Now Makes Big Bolts See Case Study Installation of a 160mm diameter Drillco Maxi-Bolt at a steel mill in Alabama The undercutting tool before being lowered into a pre-drilled hole. The undercutting blades are shown at the bottom of the tool. The three lower rings center the tool in the drilled hole. The upper ring controls the depth of tool insertion. Undercutting blades in retracted position. Undercutting blades in extended position. Drilling the undercut in the hole with a core drill. View down the hole after the undercut is complete. Notice the steel rebar cut in the undercut area. Raising the Maxi-Bolt anchor into position. 160mm diameter Maxi-Bolt before insertion into undercut hole. Closeup of lower part of anchor sleeve and conical nut. Using hydraulic cylinder to draw the conical nut up into the sleeve. The sleeve bends laterally to fill the undercut area. Completed installation.