Mahr Micromar 844 EWR Digital Inside Measure Gage
The Mahr Micromar 844 EWR is a digital 3-point inside measuring instrument designed for fast, accurate, and repeatable internal diameter measurement in production machining, quality control, and inspection environments. Available in measuring ranges from 6mm to 100mm (0.25" to 3.94") across fourteen head-size configurations, the 844 EWR delivers 0.001mm / 0.00005" resolution with spring-loaded measuring force and automatic self-centering, combining the geometric precision of 3-point inside measurement with an ergonomic pistol-grip body and lever retraction mechanism that make it one of the fastest handheld bore gages available for high-throughput production use.
The fundamental measurement principle behind the 844 EWR are the three anvils arranged at 120° intervals which is what separates it from 2-point telescoping gages and dial bore gages in both accuracy and ease of use. The system is self-centering with its 3-anvil design (offset 3 x 120°). This geometry automatically centers the measuring head on the bore axis regardless of operator skill level, eliminating the rocking and tilting technique required to find the true minimum reading with a 2-point gage. The result is a measurement that is both faster and more reproducible across multiple operators, making the 844 EWR well suited for production floor gaging where speed and consistency across operator populations both matter.
The stroke path covers the entire range of application of the respective measuring head. With the red control buttons in the lever, users can either trigger a data command or activate the hold function. Ideal for situations where they do not have a direct view of the device display (e.g. in the machine). This is a meaningful operational advantage when measuring blind holes, deep bores, or bores inside machine tools or fixtures where the inspector is working with limited sightlines. The spring-loaded measuring force guarantees a high level of reproducibility of the measurement results for measurements such as through-hole or blind holes.
The integrated display module rotates to any orientation and can be read from any angle, with extra-hardened glass protecting the display face from the shop floor impacts that damage conventional LCD panels. Colored LEDs provide immediate visual tolerance classification (green for in-tolerance, red for out-of-tolerance) allows the operator to confirm a pass or fail result at a glance without reading the numerical display, which is particularly valuable in high-paced production environments where cycle time per part is closely managed. Three preset and tolerance values are available for dimension presetting, accommodating multi-diameter inspection routines without requiring manual re-entry of nominal and tolerance values between bore checks.
Measuring anvils are carbide tipped from 12 mm, and from 12 mm they allow measurements up to the bottom of the bore. For the smallest range heads below 12mm, chrome-plated measuring anvils provide corrosion resistance in coolant and cutting fluid environments. Measuring head housings from 40mm and above transition to anodized aluminum with stainless steel front panels for reduced weight at larger diameters without sacrificing durability. The 844 EWR is available in a wired configuration (EWR bidirectional MarConnect data output via cable) and an integrated wireless configuration (EWRi ANT+ wireless to the Mahr i-Stick USB receiver), with both variants supported by free MarCom Professional software for PC-based remote control, key locking, configuration, and data collection.
Key Features
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3-Anvil Self-Centering at 120° - Three measuring contacts positioned at equal 120° intervals around the bore circumference automatically center the measuring head on the bore axis regardless of insertion angle or operator technique, eliminating the skill-dependent rocking method that 2-point dial bore gages require to find the true minimum and delivering consistent, reproducible diameter readings from the first measurement cycle, making the 844 EWR equally accurate in the hands of experienced metrologists and production floor operators with minimal gaging training.
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Full-Stroke Lever Retraction with In-Lever Data and Hold Buttons - A single lever stroke retracts the measuring head through the complete application range of the installed measuring head, enabling fast part entry and retraction without multiple actuations; red control buttons integrated directly into the retraction lever trigger data transmission or activate the hold function without touching the instrument body and allowing the operator to capture and lock a reading even when the bore is deep, confined, or inside a machine tool where the display is not visible during measurement.
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Spring-Loaded Measuring Force - The spring-loaded contact force system applies a consistent, calibrated measuring force independently of operator hand pressure, eliminating one of the primary sources of cycle-to-cycle variation in handheld bore measurement; this is especially relevant for blind hole measurement, where the operator cannot use tactile feedback from bore contact to judge whether force has been correctly applied, and for production-floor use where many operators with varying technique must produce statistically comparable results.
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Rotating Display with Colored LED Tolerance Classification and Extra-Hardened Glass - The integrated display module rotates freely to any orientation for clear readout in any measurement position or gage mounting configuration; colored LEDs instantly classify each measurement as in-tolerance (green) or out-of-tolerance (red) without requiring the operator to interpret numerical values during fast-paced production inspection; and the extra-hardened glass display face resists the scratches, chips, and impacts from workpiece handling and shop floor use that degrade conventional LCD panels over time.
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Three Preset and Tolerance Value Storage - Up to three nominal dimension PRESET values and their associated tolerance limits can be stored in the instrument simultaneously, allowing the operator to cycle between bore checks on parts with multiple different diameter specifications without manually re-entering nominal values between measurements; this reduces setup time per part, eliminates re-entry errors, and supports structured multi-feature inspection routines on complex machined components where several bore diameters must be checked in a defined sequence.
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Wired and Wireless Data Output - The 844 EWR (wired) provides bidirectional MarConnect data output via USB cable for direct connection to PCs, SPC software, and data collection systems; the 844 EWRi adds Integrated Wireless ANT+ transmission to Mahr's i-Stick USB receiver, enabling cable-free data collection to any Windows application at the cursor position with both variants supported by free MarCom Professional software for remote PC control, key lock configuration, and measurement data management; up to eight 844 EWRi instruments can connect to a single i-Stick receiver simultaneously.
Specifications
| SKU |
Specifications |
| 4192205 |
6 - 8 mm Res. 0,001 mm |
| 4192206 |
8 - 10 mm Res. 0,001 mm |
| 4192207 |
10 - 12 mm Res. 0,001 mm |
| 4192208 |
12 - 16 mm Res. 0,001 mm |
| 4192209 |
16 - 20 mm Res. 0,001 mm |
| 4192210 |
20 - 25 mm Res. 0,001 mm |
| 4192211 |
25 - 30 mm Res. 0,001 mm |
| 4192212 |
30 - 40 mm Res. 0,001 mm |
| 4192213 |
40 - 50 mm Res. 0,001 mm |
| 4192214 |
50 - 60 mm Res. 0,001 mm |
| 4192215 |
60 - 70 mm Res. 0,001 mm |
| 4192216 |
70 - 85 mm Res. 0,001 mm |
| 4192217 |
85 - 100 mm Res. 0,001 mm |
| 4192305 |
6 - 8 mm Res. 0,001 mm |
| 4192306 |
8 - 10 mm Res. 0,001 mm |
| 4192307 |
10 - 12 mm Res. 0,001 mm |
| 4192308 |
12 - 16 mm Res. 0,001 mm |
| 4192309 |
16 - 20 mm Res. 0,001 mm |
| 4192310 |
20 - 25 mm Res. 0,001 mm |
| 4192311 |
25 - 30 mm Res. 0,001 mm |
| 4192312 |
30 - 40 mm Res. 0,001 mm |
| 4192313 |
40 - 50 mm Res. 0,001 mm |
| 4192314 |
50 - 60 mm Res. 0,001 mm |
| 4192315 |
60 - 70 mm Res. 0,001 mm |
| 4192316 |
70 - 85 mm Res. 0,001 mm |
| 4192317 |
85 - 100 mm Res. 0,001 mm |
| 4192240 |
6 - 12 mm , in Set |
| 4192241 |
12 - 20 mm , in Set |
| 4192242 |
20 - 50 mm , in Set |
| 4192242KAL |
20-50 mm , in Set with certificate |
| 4192243 |
50 - 100 mm , in Set |
| 4192243KAL |
50-100 mm , in Set with certificate |
| 4192340 |
6 - 12 mm , in Set |
| 4192342 |
20 - 50 mm , in Set |
| 4192343 |
50 - 100 mm , in Set |
| 4192260 |
for meas. heads 6-20 mm |
| 4192261 |
for meas. heads 20-100 mm |
| 4192341 |
12 - 20 mm , in Set |
| 4192360 |
for meas. heads 6-20 mm |
| 4192361 |
for meas. heads 20-100 mm |
Items Included
- Mahr Micromar 844 EWR basic unit (handle with lever retraction) - size matched to measuring range
- Measuring head 44 Ak (matched to specified measuring range)
- Shock protection ring 1086 sr
- Hexagonal wrench
- CR 2450N battery (installed)
- Instruction manual
- Carrying case
Mahr Micromar 844 EWR Digital Inside Measure Gage - 4192205 Datasheet
Mahr Micromar 844 EWR Digital Inside Measure Gage - 4192310 Datasheet
