Fowler 52-243-212-1 Inside Micrometer Set 2-12 in

Product Description

The FOWLER 52-243-212-1 is a mechanical inside micrometer set designed for precision internal bore and ID measurements across a 2 to 12 inch range. The set uses a single measuring head paired with five extension rods, allowing technicians to cover a wide measurement span without switching instruments. Solid carbide measuring faces deliver durability in repetitive use. Accuracy is rated at 0.0007 inches, making this set suitable for close-tolerance work in machining, maintenance, and fabrication environments. The friction thimble provides consistent measuring force, and a positive locking nut holds the spindle in position during reading transfer.

This inside micrometer set is used in machine shops, industrial maintenance facilities, and precision fabrication settings where accurate internal diameter measurements are required. Typical applications include measuring cylinder bores, bushing IDs, bearing seats, and housing bores. The five-rod extension system allows a single head to service a broad range of bore diameters, reducing tooling cost and setup time. The set ships factory-calibrated and includes a standard, wrench, and fitted case for organized storage and transport.

Key Features

• Measurement range of 2 to 12 inches via five extension rods and one measuring head
• Solid carbide measuring faces for wear resistance and long service life
• Friction thimble for consistent, repeatable measuring force
• Positive locking nut on spindle secures reading before transfer
• Anvil and spindle are hardened and precision ground with microlap finish on ends
• Spindle thread hardened, ground, and lapped for smooth, accurate advancement
• Factory-calibrated and includes fitted case, standard, and wrench

Compatibility

Designed as a general-purpose mechanical inside micrometer set suitable for standard inch-system metrology applications in machine shops and industrial maintenance environments.

Installation Notes

Inside micrometer sets are installed and serviced by machinists, metrologists, and precision maintenance technicians. Before use, verify calibration against the included standard and ensure the measuring faces are clean and free of debris. Follow shop metrology procedures for handling carbide-tipped instruments to avoid chipping the measuring faces. Store the set in the fitted case when not in use to protect the extension rods and measuring head from damage.