Mitutoyo 145-218 Caliper-Type Inside Micrometer, 225-250mm - Anvil Jaw, 0.01mm Graduation

The Mitutoyo 145-218 is a caliper-type inside micrometer from Series 145, built for direct measurement of internal diameters, groove widths and other inside dimensions from 225-250 mm. Unlike a tubular inside micrometer, the caliper jaws reach into features that a straight rod cannot, and this model is fitted with anvil jaws to suit bores, bosses, slots and other internal diameters across its range.

Both measuring faces are carbide tipped, so they hold their geometry through heavy shop-floor use. A constant measuring-force device applies the same force on every reading, which is what keeps results repeatable between operators rather than depending on feel. A locking clamp holds the spindle so the micrometer can be withdrawn from the bore and read without the setting shifting, and the satin-chrome finish on the thimble and sleeve cuts glare under shop lighting.

The thimble is graduated in 0.01 mm and the instrument is accurate to +/-11 um across its range. With no battery or electronics there is nothing to fail or discharge, which makes the analogue models a practical choice for tool cribs, gauge rooms and anywhere the instrument sits unused for long stretches between jobs.

Key features

• Measuring range: 225-250 mm
• Graduation: 0.01 mm
• Accuracy: +/-11 um
• Anvil jaws, carbide-tipped measuring faces
• Satin-chrome finished thimble and sleeve
• Spindle lock clamp and constant measuring-force device
• No battery or electronics

Supplied in a fitted case with a spanner. A setting standard is required to set the micrometer to its reference point and is not supplied; setting rings, the CERA Inside Micro Checker and gauge block accessory sets are available separately. A cap and holder are needed to mount the instrument on a micrometer stand.