Original price was: $ 476.56.$ 409.17Current price is: $ 409.17.
Mitutoyo 331-251-30 Digital Spline Micrometer IP65 – precision measurement for splined shafts, slots & keyways with waterproof protection.
The Mitutoyo 331-251-30 Digital Spline Micrometer IP65 is a high-precision measuring tool engineered for grooves, splined shafts, slots, and keyways. Designed with a small-diameter anvil and spindle, it ensures accurate measurements in difficult-to-reach profiles. Its IP65 protection rating guarantees excellent resistance to dust, oil, and coolant splash, making it suitable for workshop and machining environments. With carbide-tipped measuring faces, high accuracy of ±2 µm, and user-friendly digital display, it is a reliable tool for demanding inspection tasks.
The Mitutoyo 331-251-30 offers 0–25 mm measuring range, 0.001 mm resolution, and a maximum permissible error of ±2 µm. It features a robust IP65 protection against dust and water, a clear LCD display with 7.5 mm character height, and a carbide-tipped, micro-lapped spindle and anvil for long-lasting precision. Equipped with a spindle lock, origin setting, data output, and function lock, this micrometer is optimized for both workshop and laboratory use. Battery-powered (SR44) with up to 2.4 years of life, it provides stable and dependable measurements under industrial conditions
Because it combines ultimate precision with industrial durability. Unlike conventional micrometers, the 331-251-30 is specifically designed for spline and slot measurements, giving engineers confidence when working on complex shafts or keyways. Its compact spindle design, IP65 water resistance, and long battery life mean you can use it directly in machining environments without fear of coolant splash or dust. In short, it’s not just a micrometer—it’s a specialist tool for specialists.
Traditional micrometers struggle with grooves, splined shafts, and narrow slots due to their large spindle sizes and lack of environmental resistance. The Mitutoyo 331-251-30 solves this by featuring small-diameter anvils for tight-area access and IP65 protection for reliable operation even under coolant or dust exposure. This makes it an indispensable solution for precision measurement in challenging conditions, reducing inspection errors and increasing productivity in industries like automotive, aerospace, and high-precision machining.
On gearbox assembly lines, engineers verify minor diameter and groove width on splined shafts without removing parts from fixtures. The micrometer’s small-diameter anvil/spindle reaches into narrow spline roots, while 0.001 mm resolution and ±2 µm accuracy support tight tolerances. IP65 lets inspectors measure near machines where coolant and chips are present, and data output streamlines SPC logging to catch drift early.
During actuator overhaul or new-build inspection, technicians confirm keyway width and parallelism to ensure proper key fit and torque transmission. The stepped, carbide-tipped faces resist wear and provide consistent contact on edges, while the spindle lock stabilizes readings. IP65 protection permits shop-floor checks after machining or cleaning, reducing travel between metrology labs and cells and cutting turnaround time on critical hardware.
Toolrooms use the micrometer to validate relief grooves, ejector slots, and hub slots where standard anvils can’t seat. The Type A, 3 mm anvil accesses tight geometries; ABS/INC origin avoids cumulative zeroing mistakes during repeated checks. The LCD (7.5 mm characters) aids quick readouts under shop lighting, and the ±2 µm MPE ensures acceptance decisions align with fine tolerance bands in mold and die work.
Operators measure sample parts at the spindle to tune offsets before full runs. IP65 sealing keeps performance stable with splashing coolant, while function lock/HOLD prevents accidental setting changes. With ~2.4-year SR44 battery life and optional data output for wireless capture, the tool supports frequent checks without downtime, helping reduce scrap, stabilize Cp/Cpk, and maintain dimensional capability across shifts.
| Feature | Details | Benefit |
|---|---|---|
| Model | Mitutoyo 331-251-30 (SPM-25MX) | Identifies exact model for reliable sourcing and compatibility |
| Measuring Range | 0 – 25 mm | Covers small precision parts like splined shafts, grooves, and keyways |
| Resolution | 0.001 mm | Provides ultra-fine measurement for tight tolerance applications |
| Maximum Permissible Error (MPE) | ±2 µm | Ensures consistent and traceable accuracy |
| Flatness | 0.3 µm | Guarantees surface contact precision |
| Parallelism | 2 µm | Maintains alignment for highly accurate readings |
| Measuring Faces | Carbide-tipped, micro-lap finish, stepped type | Enhances durability and precision, reduces wear over time |
| Anvil/Spindle Size | Type A, 3 mm diameter | Ideal for measuring narrow splines and keyways |
| Display | Large LCD, 7.5 mm character height | Improves visibility for quick, error-free reading |
| Spindle | ø6.35 mm, pitch 0.5 mm with lock | Stable operation with secure locking during measurement |
| Protection | IP65 (dustproof & coolant resistant) | Reliable use in harsh machining environments |
| Data Output | Yes (Digimatic/USB/Bluetooth options) | Easy integration into SPC/QA systems for digital workflow |
| Functions | ORIGIN, ABS/INC zeroing, HOLD, Function lock, Auto power-off, Low voltage alarm | Increases usability, prevents operator errors, and extends battery life |
| Power Supply | 1 × SR44 battery (approx. 2.4 years life) | Long operational life reduces downtime and cost |
| Measuring Force | 5 – 10 N | Consistent measuring pressure ensures repeatable results |
| Dimensions | 58.2 × 17.5 × 7.3 × 32.5 mm | Compact design fits well in inspection setups |
| Weight | Approx. 330 g | Lightweight, portable, and easy to handle |
| Accessories | Micrometer stand, Digimatic cables, U-WAVE wireless transmitter | Expands capability for data transfer and ergonomic use |
| Applications | Splined shafts, grooves, keyways, narrow slots, and precision machining parts | Tailored solution for industries like automotive, aerospace, and toolmaking |
| L: |
58,2 mm
|
| a: |
17,5 mm
|
| b: |
7,3 mm
|
| c: |
32,5 mm
|
All products of product family Series 331:
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Digital Spline Micrometer IP65 |
| 0-25mm, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-261-30 | |
| More Info | |
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Digital Spline Micrometer IP65 |
| 0-25mm, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-251-30 | |
| More Info | |
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Digital Spline Micrometer IP65 |
| 25-50mm, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-252-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| 25-50mm, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-262-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| 50-75mm, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-253-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| 50-75mm, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-263-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| 75-100mm, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-254-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| 75-100mm, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-264-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 0-1″, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-351-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 0-1″, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-361-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 1-2″, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-352-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 1-2″, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-362-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 2-3″, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-353-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 2-3″, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-363-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 3-4″, 3mm Measuring Face | |
| Mitutoyo Part Number: 331-354-30 | |
| For more : Contact us | |
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Digital Spline Micrometer IP65 |
| Inch/Metric, 3-4″, 2mm Measuring Face | |
| Mitutoyo Part Number: 331-364-30 | |
| For more : Contact us |
Optional accessories:
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Micrometer Stand, 45° Angle Type |
| for Micrometer 0-50mm/0-2″ | |
| Mitutoyo Part Number: 156-105-10 | |
| For more : Contact us | |
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Micrometer Stand, Adjustable Angle Type |
| for Micrometer 0-100mm/0-4″ | |
| Mitutoyo Part Number: 156-101-10 | |
| More Info | |
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Connection Unit for IP Caliper, Micrometer |
| with Data Button for U-WAVE fit, U-WAVE fit Bluetooth | |
| Mitutoyo Part Number: 02AZF310 | |
| For more : Contact us | |
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USB Input Tool Direct (Digimatic to USB) |
| 2m Cable, Digimatic/Digimatic 2, with Data Button IP Micrometer Type | |
| Mitutoyo Part Number: 06AFM380B | |
| More Info | |
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Digimatic Cable with Data Button IP Type |
| 1m, Micrometer Type | |
| Mitutoyo Part Number: 05CZA662 | |
| More Info | |
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Digimatic Cable with Data Button IP Type |
| 2m, Micrometer Type | |
| Mitutoyo Part Number: 05CZA663 | |
| For more : Contact us | |
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U-WAVE fit, IP67 Type |
| Wireless Transmitter for Micrometer/Indicator | |
| Mitutoyo Part Number: 264-622 | |
| For more : Contact us | |
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U-WAVE fit, Buzzer Type |
| Wireless Transmitter for Micrometer/Indicator | |
| Mitutoyo Part Number: 264-623 | |
| For more : Contact us | |
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U-WAVE fit Bluetooth, IP67 Type |
| Wireless Transmitter for Micrometer/Indicator | |
| Mitutoyo Part Number: 264-626 | |
| For more : Contact us | |
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U-WAVE fit Bluetooth, Buzzer Type |
| Wireless Transmitter for Micrometer/Indicator | |
| Mitutoyo Part Number: 264-627 | |
| For more : Contact us |
Consumable spares:
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Battery SR44 1.5V |
| 938882 | |
| For more : Contact us |
For expert guidance before placing your order.
Warranty – 1-year warranty for your peace of mind.
Global Shipping – We ship worldwide with secure packaging and reliable delivery.
Technical Support – Contact us for professional after-sales technical assistance.
