Reverse Circulation Underreamer

To meet application needs, Mills Machine Co. offers a variety of customized underreamers. For example, LaFramboise Drilling of Thompson, Conn., needed to underream with reverse circulation through an 18-inch casing to open up to 36 inches in sand and gravel. The hole needed to open up at depths from 375 feet to 450 feet. Mills Machine designed a reverse circulation, two-blade underreamer to do the job. The flange mount bit used a 17 7¿inch two-blade pilot bit and pivoting arms on the body to open up beyond the casing. Mills Machine Co., Card No. 276