91 deg Turning Tool
STGCR/L toolholders use the three 60º corners of TCMT inserts, mounted at 91º to the axis of the machine. Where only straight turning is to be done (whether or not to a square shoulder), these are the most economical tools to use. This is because the inserts have 3 edges, giving a lower cost per edge.
Shank sizes 8,10 use Insert Type 4
Shank sizes 12,16 use Insert Type 5