Abstract: The invention relates to drill means of the type to drill and ream a hole in the ground in advance of a trailing casing tube. Drill means able to drill an oversize hole, and yet allow the drill means to be withdrawn through the casing tube when in place in the hole are known such as in U.S. Pat. No. 3,848,683. Such means are effective but are relatively complex, and the object of the invention is to provide a relatively simple inexpensive drill means capable of drilling an average hole and enabling subsequent extraction through a casing tube.