Designed and patented by Kenneth Hart (aka "Martin Cleeves") in August 1970 and described in his definitive work, "Screw Cutting in the Lathe". This simple mechanism provides 5/32" (4mm) of retraction for both external and internal thread cutting together with a unique 'swing' feature, allowing it to be flipped clear of the job for gauging those final internal cuts. This tool post is also ideal for fine boring operations, where constant gauging takes place.
The Hemingway Kits design for this item is suitable for a number of lathes up to around 5" Centre Height and importantly, it can swing clear of the fairly tall 7/16" BSF tool post of the Myford 7 range . To improve integrity, the swinging arm is milled from a steel block rather than fabricated. Extra work perhaps but the solidness of the finished item fully justifies this approach.
The kit includes all of the necessary bar materials and fasteners together with the drawing set and, for interest, a copy of Mr. Hart's granted patent. Unfortunately construction notes are not available and we would welcome your photos and notes for this project.