Roll “wind-up” caused by one roll rotating counter to the direction of attachment advance as the rolls move into the work, is automatically compensated for, by an advance compensating device within the head without placing any undue strain on the gear train. The Advance Compensator insures perfect synchronization of the thread rolls during rolling operation.

Accurate positioning of the rolls in the head, accomplished by four independently adjustable arms, and a vertical floating arrangement in the adapter, provides automatic parallel alignment of the rolls with the center line of the work throughout the rolling cycle. The Alignment Compensator also assures smooth contacting and withdrawal of the rolls to and from the work.

Anti-friction thrust bearings on both sides of the thread rolls minimizes unnecessary wear on the rolls from any side movement. Not only is this important when rolling straight threads, but it also accounts for exceptional performance when taper Pipe threading.

Precise matching of the rolls is important in the operation of a two-roll geared type thread rolling attachment. To obtain accurate threads, it is necessary that the rolls track property on the work blank. The simple micrometer adjusting device provides a positive means of positioning both rolls for proper tracking.

The dovetail design of the connection between the head and the adapter makes it possible to easily remove the head from the machine for changing or adjusting rolls, or for convenience in making adjustments, without removing the adapter from the cross slide. This feature combined with an adjustable and positive locating stop, assures that the head will always be reassembled in the adapter in the same relative position to the work.