#9091 Square GO / NO-GO Ring Gage – Robertson Drive

The #9091 Square GO / NO-GO Ring Gage is a precision inspection tool designed to verify square driver bit and screwdriver geometry manufactured to Robertson square drive standards.

Square recess systems, commonly referred to as Robertson drive, require proper driver conformity to ensure full engagement, accurate torque transmission, and reduced cam-out during assembly.

The 9091 Series provides functional GO and NOT GO inspection to verify driver dimensional conformity.

The GO ring verifies minimum allowable driver geometry to ensure proper engagement.The NOT GO ring ensures the driver does not exceed maximum dimensional limits.

Available sizes:

9091-00 – Size 00

9091-0 – Size 0

9091-1 – Size 1

9091-2 – Size 2

9091-3 – Size 3

9091-4 – Size 4

The 9091 Series is ideal for:

• Driver bit manufacturers

• Screwdriver manufacturers

• Fastener producers

• Industrial assembly operations

• Quality inspection laboratories

Ring gages are heat treated, thermally stabilized, and surface treated to maximize wear resistance and dimensional stability.

Long form calibration certificates provide dimensional verification and traceability to the National Institute of Standards and Technology, NIST.

The 9091 Series ensures accurate and repeatable square driver conformity verification.