Starrett Inside Hole Micrometers
Find the inside diameter of cylinders and rings. These micrometers have a plain thimble, which relies on operator feel for accurate measurements.
124 series have solid steel extensions that attach at one end of the micrometer head.
823 series have lightweight tubular extensions that can attach at either end of the micrometer head.
Collars (sold separately) extend a micrometer’s measuring range. Handles (sold separately) screw into a micrometer head to extends its reach for measuring deep holes.
| Measuring Range | Accuracy | Measuring Increments | Material | Number of Extension Rods | Extension Rod Dia. | Number of Heads | Head Travel | Includes | Manufacturer Model Number | Each | |
124 Series—Plain Thimble | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 2"-8" | ±0.0001" | 0.001" | Steel | 6 | 1/4" | 1 | 1/2" | __ | 124AZ | 000000 | 0000000 |
| 2"-12" | ±0.0001" | 0.001" | Steel | 10 | 1/4" | 1 | 1/2" | __ | 124BZ | 000000 | 000000 |
| 2"-32" | ±0.0001" | 0.001" | Steel | 10 | 1/4", 11/32" | 2 | 1/2", 1" | __ | 124DZ | 000000 | 00000000 |
| 8"-32" | ±0.0001" | 0.001" | Steel | 4 | 11/32" | 1 | 1" | __ | 124CZ | 000000 | 000000 |
823 Series—Plain Thimble | |||||||||||
| 1.5"-8" | ±0.0001" | 0.001" | Steel | 5 | 3/8" | 1 | 1/2" | 5 1/2" Lg. Handle | 823AZ | 000000 | 000000 |
| 1.5"-12" | ±0.0001" | 0.001" | Steel | 8 | 3/8" | 1 | 1/2" | 5 1/2" Lg. Handle | 823BZ | 000000 | 000000 |
| 1.5"-32" | ±0.0001" | 0.001" | Steel | 10 | 3/8" | 2 | 1/2", 1" | 5 1/2" Lg. Handle | 823FZ | 000000 | 00000000 |
| 4"-24" | ±0.0001" | 0.001" | Steel | 7 | 3/8" | 1 | 1" | __ | 823CZ | 000000 | 000000 |
| 4"-32" | ±0.0001" | 0.001" | Steel | 8 | 3/8" | 1 | 1" | __ | 823DZ | 000000 | 000000 |
| 4"-40" | ±0.0001" | 0.001" | Steel | 10 | 3/8" | 1 | 1" | __ | 823EZ | 000000 | 000000 |
Inside Hole Micrometers for Grooves
Reach into bores to measure the precise size and location of grooves. These micrometers have two discs on their measuring spindle to find a groove’s edge. Slide the spindle into your bore, press the discs against the wall and into the groove, and twist the thimble to measure the distance between the two discs. A speeder knob moves the measuring spindle more quickly toward or away from your groove, without turning the thimble repeatedly. When the spindle touches the groove you’re measuring, it will stop tightening, but the speeder knob will continue turning with a clicking sound. The spindle doesn’t rotate, so the contact points won’t spin or slip out of a groove.
Measuring Range | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Inside | Outside | Accuracy | Measuring Increments | Material | Overall Lg. | Manufacturer | Manufacturer Model Number | Each | |
Ratchet-Stop Thimble—Nonrotating Spindle | |||||||||
| 0.055"-1.05" | 0"-1" | ±0.0004" | 0.001" | Steel | 9 1/2" | Mitutoyo | 146-232 | 0000000 | 0000000 |
| 1.05"-2.05" | 1"-2" | ±0.0004" | 0.001" | Steel | 9 1/2" | Mitutoyo | 146-233 | 0000000 | 000000 |
| 2.05"-3.05" | 2"-3" | ±0.0004" | 0.001" | Steel | 9 1/2" | Mitutoyo | 146-234 | 0000000 | 000000 |
| 3.05"-4.05" | 3"-4" | ±0.0004" | 0.001" | Steel | 9 1/2" | Mitutoyo | 146-235 | 0000000 | 000000 |
Caliper-Style Inside Hole Micrometers
The jaws on these micrometers work like caliper jaws to precisely measure inner diameters. These micrometers have a friction thimble with a constant-force mechanism, so they stop tightening once both jaws touch the sides for repeatable measurements. When the jaws stop tightening, the thimble continues turning with resistance, preventing overtightening. Use the included setting ring to calibrate and verify the accuracy of these micrometers.
Micrometers with pointed tips help you measure small shapes on your workpiece. Their thin tips fit into recesses and grooves, such as those found in keyways.
Micrometers with anvil tips are used to take quick ID measurements. A wide surface keeps the tips from catching on ridges or bumps, so it’s easy to position them across the diameter of your workpiece.
Measuring Range | Accuracy | Measuring Increments | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Inch | Metric | Inch | Metric | Inch | Metric | Body Material | Jaw Material | Batteries Included | Includes | Each | |
Pointed Tips | |||||||||||
Friction Thimble | |||||||||||
| 0.2"-1.2" | 5 mm-30 mm | ±0.0002" | ±0.005 mm | 0.00005" | 0.001 mm | Steel | Steel | Yes | Setting Ring | 000000 | 0000000 |
Anvil Tips | |||||||||||
Friction Thimble | |||||||||||
| 1"-2" | 25 mm-50 mm | ±0.0002" | ±0.005 mm | 0.00005" | 0.001 mm | Steel | Steel | Yes | Setting Ring | 000000 | 000000 |
Economy Inside Hole Micrometers
Measure the inside diameter of cylinders and rings. These micrometers have a plain thimble that turns freely without friction or a stopping device. It relies on user feel for accurate measurements. All include steel extensions that you can attach to one end of the micrometer head.
Mitutoyo Electronic Inside Hole Micrometers
With an LCD screen, these micrometers make it easy to read inside diameter measurements taken from cylinders and rings. Place the micrometer inside your bore, then turn the thimble until the spindle makes contact with both sides. For an accurate reading, stop turning as soon as you feel resistance on the thimble.
USB data cables (sold separately) connect micrometers directly to your PC.
10-pin data cables (sold separately) connect micrometers to a Mitutoyo miniprocessor or multiplexer.
Wireless data transmitters and receivers (sold separately) let you send data from micrometers to your PC without a cable.
Measuring Range | Accuracy | Measuring Increments | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Inch | Metric | Inch | Metric | Inch | Metric | Material | Number of Extension Rods | Extension Rod Dia. | Number of Heads | Head Travel | Batteries Included | Manufacturer Model Number | Each | |
303 Series—Plain Thimble | ||||||||||||||
| 8"-40" | 204 mm-1,016 mm | ±0.0015" | ±0.040 mm | 0.0001" | 0.001 mm | Steel | 6 | 5/8" | 1 | 1" | Yes | 339-303 | 0000000 | 000000000 |
Mitutoyo Inside Hole Micrometers
Find the inside diameter of cylinders and rings. Rotate the plain thimble until it fits snugly inside the space you’re measuring. These micrometers rely on the operator to determine a secure fit to take accurate measurements. Attach one of the included extension rods to the micrometer head to measure in hard-to-reach spaces.
Shallow Inside/Outside Diameter Gauges
Mount your variance indicator onto these gauges to measure the diameter of rims and shallow holes. They show deviation from a set reference to measure both internal and external diameters, while other tools like micrometers and bore gauges only take one type of measurement. Commonly used in cramped machining or assembly processes, these gauges fit in tight spaces. They are made from hardened steel, so they are durable enough to withstand bumps and scrapes and will stay accurate over time.
To set your reference measurement, use gauge blocks or a ring gauge. Place the contact pin on one side of the gauge blocks or ring, and slide the indicator away from the contact pin. This pinches the gauge blocks between the contact pin and indicator for outer diameter measurements or presses against the inner edge of the reference gauge for inner diameter measurements. Once the reference measurement is set, lock the gauge. Set the indicator to zero and you're ready to take your measurement. The indicator point stopper will flex slightly to fit the gauge into bores and around outer edges.
For technical drawings and 3-D models, click on a part number.
| Inside Measuring Range | Outside Measuring Range | Max. Dp. Measured | Material | Overall Lg. | Overall Ht. | Heat Treatment | Container Type | Features | Includes | Each | |
| 0.55"-7.2" | 0.24"-6.92" | 0.4" | Black-Oxide Tool Steel | 7 3/4" | 2 3/4" | Hardened | Cardboard Box | Fine-Adjustment Knob, Indicator Contact Point Stopper | Contact Pin, Two L-Keys | 0000000 | 0000000 |
| 2"-12.1" | 1.95"-12.05" | 0.4" | Black-Oxide Tool Steel | 12 7/8" | 2 3/4" | Hardened | Plastic Box | Fine-Adjustment Knob, Indicator Contact Point Stopper | Contact Pin, Two L-Keys | 0000000 | 000000 |