The JBO Thread Plug Gauge is a precision inspection tool designed to verify internal UNF threads in holes. Specifically tailored for right-hand 1/2 x 20 UNF threads and 3B tolerance, it helps machinists, inspectors, and maintenance teams quickly confirm bore readiness and thread conformity. It’s a reliable choice for manufacturing, automotive, and aerospace environments where consistent thread quality matters.

With a robust, knurled body and durable finish, this Go/No-Go gauge is built to perform in busy shop floors. Its solid construction provides dependable measurements across shifts, helping teams maintain accurate bore checks without slowing down production.

• Go/No-Go design for fast bore conformance: Quickly determine whether the thread hole meets the 1/2-20 UNF, 3B specification, enabling rapid pass/fail decisions and reducing inspection time.
• Precise 1/2-20 UNF, 3B tolerance: Ground to exact UNF thread profile and class 3B tolerance, delivering reliable checks that fit real-world manufacturing and assembly needs.
• Rugged, ergonomic construction: Knurled, corrosion-resistant body provides secure handling and long service life in demanding environments.

This plug gauge helps streamline inspection workflows, minimize guesswork, and ensure threaded holes will assemble correctly and perform as intended. By delivering consistent, on-the-spot verification, it supports quality, reduces rework, and keeps production moving smoothly.