GROZ SCREW CUTTING GAUGE Manufactured from hardened and polished stainless steel all gauge surfaces are accurately ground. It is most useful for checking tool angle while cutting threads in metal turning lathes. The angle on the thread cutting tool is checked on the V slots in the gauge. The gauge clearly indicates 55° for Whitworth and BSF Threads; 47½° for BA Threads 60° for Metric and American National Threads and 14½° for Acme threads.