in the form 3 and the form is filled with a concrete mixture 5 the number and size of air bubbles present in the form at the conclusion of the pour will vary depending upon the size of the aggregate and the slump with a 6 inch slump being generally preferred in use the vibrator apparatus 1 is installed on a portable hand drill 2 in the manner shown in fig2 by installing the stub shaft 25 into the drill chuck 31 and tightening the chuck 31 an exemplary drill is a u00bd inch portable battery operated hand drill manufactured under the trademark dewalt u00ae although any other chucking drill motor may be employed on high drive such a drill will deliver about 1800 revolutions per minute rpm a user actuates the drill which drives the camshaft 23 causing it to rotate axially within the bore 13 through a motion cycle in which the cam 23 rides in and out over the fixed follower 32 it is foreseen that other means for rotating the shaft 23 such as a motor may be substituted for the portable hand drill 2 and that the motor means and vibrator 1 may be of unitary construction or in a single unit fig5 7 depict rotation of the cam 23 through the return portion of a motion cycle in which the cam center 27 moves toward the fixed follower in fig5 the cam 23 is positioned at its lowest point in the bore 13 with the follower 32 farthest away from.