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Digital Radius Gauge/Arc Meter

We’ve covered everything you need to know about the Digital Radius Gauge/Arc Meter from BIT. You should also check out our Minimum Recommended Bend Radius Chart page.

art meter

Digital Radius Gauge/Arc Meter is a precision measurement tool used to determine the radius of curved surfaces with high accuracy. It typically consists of a handheld device equipped with digital sensors and a digital display screen. The gauge is designed to be placed against the curved surface, and it measures the radius automatically, displaying the result on the digital screen. This type of gauge offers advantages over traditional manual radius measurement methods by providing faster, more accurate, and consistent results. It is commonly used in manufacturing for quality control, inspection, and dimensional verification purposes.


digital radius gauge
  • Digital Radius Gauge/Arc Meter: It’s a new type of high-tech radius measuring tool—-a multifunctional digital radius gauge designed using sensor technology, microcomputer technology, and integrated circuit technology. It features small size, convenient reading, and handheld measurement, suitable for use in production sites.
  • Using a ball-head measuring rod, the error compensation calculation is simple. Meanwhile, for arc measurements with different radii, the contact point varies, which can extend the service life of the measuring head and is suitable for measuring curved surfaces.
  • Relationship between measuring range, chord length, and accuracy: the lower the accuracy, the larger the measuring range; the longer the chord length, the larger the measuring radius. The minimum measurable radius is half of the chord length.
  • Adopting a design with multiple sets of measuring jaws, suitable measuring jaws with appropriate spans are selected for different radii and measurement accuracies.
  • Depending on different arcs, five different sets of measuring jaws can be selected: 50mm, 100mm, 200mm, 300mm, 400mm.

BIT Digital Radius Gauge/Arc Meter

BIT Digital Radius Gauge/Arc Meter is an indispensable tool for precision measurement, offering users the ability to instantly and directly read inner and outer radii within a range of 55 to 11.250 millimeters or 2 to 443 inches.

PBH Section Bending Machine

When integrated with profile bending machines, the digital radius gauge serves as a valuable supplement, enhancing the efficiency and accuracy of the bending process, allowing operators to make precise adjustments based on real-time measurements. This ensures consistent quality and adherence to desired specifications in the final bent products.

Furthermore, the digital radius gauge enhances productivity by facilitating rapid and accurate inspections of bent aluminum profiles. With its user-friendly interface and intuitive operation, operators can efficiently verify bending radii without any cumbersome procedures.

Advanced BIT Digital Radius Gauge

  • High-Precision Digital Radius Gauge: Utilizes a multi-set measuring claw design, capable of measuring the radius of any specification of curved surface. It features simple operation and fast reading.
  • Measuring Claw Design and Extendable Measuring Rod: Featuring a multi-set measuring claw design (5 claws for small radii, 1 claw for large radii), tailored for different radii and measurement accuracies by selecting claws with different spans. The extendable rod ensures a rapid measurement speed exceeding 1.5m/s.
  • Data Output Port and Battery Compartment: Equipped with a USB output port for connecting to a computer or printer for data processing (data cable sold separately); powered by a 3V R2032 button battery, easily removable for convenient battery replacement (when installing the battery, ensure the negative pole is facing upwards and the positive pole is facing downwards). ※Note: Do not use the USB output port for charging purposes.


arc meter
  • Measurement Range: from 55 to 11.250 millimeters or from 2″ to 443″ Inches
  • Resolution: 0.01mm
  • Displacement Measurement Error: △s ≤ 0.02mm
  • Radius Measurement Error: △R ≤ 0.02 × R/s (where R is the measured radius, and s is the corresponding displacement measurement value)
  • Angle Measurement Error: △A ≤ 1°
  • Power Supply: One 3V lithium battery (CR2032)
  • Operating Temperature: 0-40℃
  • Storage Temperature: -20℃ to 60℃
  • Humidity Influence: Unaffected by relative humidity ≤ 80%


In practical applications, radius measurements are commonly performed using R templates (also known as R gauges), which rely on pure mechanical measurements. However, these methods are cumbersome, difficult to read, and often impractical due to the limitations of the measuring tools themselves. This utility model patent employs advanced technologies such as grating sensors and integrated circuits to develop a new generation of high-tech radius measurement tools. Unlike traditional methods, this patented series has an unrestricted measurement range, simplified operation, and rapid readings. Utilizing high-precision measurement tools made with grating sensors, the resolution can reach 0.01mm.

  1. Digital caliper function;
  2. Measurement of outer arc radius;
  3. Measurement of inner arc radius;
  4. Depth measurement;
  5. Step measurement.

Operation Instructions

Power On: Simply press the ZERO/ON/OFF button lightly.

digital radius gauge

Zero Setting: Press the ZERO/ON/OFF button briefly to zero at any position. For measuring inner and outer diameters, align the three rods perpendicular to a standard plane as shown in Figure 3, then press the ZERO/ON/OFF button once to complete zero setting.

Conversion between Metric and Imperial Units: Press the UNIT button to switch between metric and imperial units.

Data Hold and Release: Press the HOLD button. When “H” is displayed on the LCD screen, it indicates the data hold status. Press the button again to release the hold status.

Function Switching

This product can measure inner and outer arc radii, lengths, depths, and steps. Press the MODE button to switch functions. When the first row of the window displays “R1”, the system enters the inner arc radius measurement state. When “R2” is displayed, the system enters the outer arc radius measurement state. When “A” is displayed, an undeveloped function is not selected. The third row of the window displays the measured values ​​(chord height S) for length, depth, and step measurements. Figure 2 is for measuring outer radius R, and Figure 3 is for measuring inner radius R. During measurement, ensure that the ball heads of the three measuring rods make contact with the arc being measured simultaneously, and the plane containing the axis of the three measuring rods is coplanar with the arc being measured. The radius and chord height of the measured arc will be displayed in real-time on the LCD screen, as shown in the figure.

Claw Replacement

Select the appropriate claw according to the size of the object being measured. Generally, use larger claws for larger radii. The claws are numbered from small to large as 50, 100, 200, 300, 400. After replacing the claw, press the C button to change the C value (i.e., the claw specifications), which will be sequentially displayed on the screen as C=50, 100, 200, 300, 400. Ensure that the claw number corresponds to the C value. For example, if the 30 claw is selected, set C=30.

Power Off

Press and hold the ZERO/ON/OFF button for a long time to power off, or the device will automatically power off after a few minutes of inactivity. Pressing this button after shutdown will power on the device.

11 Key Features Showcase

Specialized scale sensor ensures fast measurement speed, eliminating freezing and jumping readings.
arc meter
  1. Suitable for places where arc measurements are needed, such as mechanical parts, wood molds, and construction steel molds;
  2. Capable of measuring the radius of any size arc surface, with simple operation and fast reading. It features small size, convenient reading, and handheld measurement.
  3. Multiple sets of measuring jaws designed for small radii, with different span measuring jaws selected for different arc surface radii and measurement accuracies.
  4. Multi-functional: High-precision digital display dial indicator function (jaw removed).
  5. Versatile measurements: outer circumference, inner arc radius measurement, depth measurement, step measurement;
  6. Switch between three modes: inner diameter/outer diameter/high precision percentage.
  7. Five sets of measuring jaws for small radii: 50/100/200/300/400 specifications conversion;
  8. Large radius gauge with a span of 300mm: measurement range for outer diameter and inner diameter is 55mm~11250mm.
  9. Features data hold, data output interface, metric/imperial conversion, zero clearing, and automatic/manual shutdown functions;
  10. Rapid measurement speed exceeding 1.5m/s;
  11. Aerospace-grade aluminum alloy body, glass grating sensor, large-capacity 3V button battery.

Precautions Before Use:

  1. If there is dust or dirt on the measuring rod of the radius tester, it will affect the movement of the rod. Therefore, please wipe the measuring rod clean with a clean cloth that does not contain oil before use.
  2. Use a soft dry cloth to wipe clean the outer shell and components such as the measuring claws of the tester. If there is severe dirt on the shell, wipe it with a damp cloth containing neutral detergent. Do not use volatile solvents such as diluents, as they may damage the shell.
  3. If the data port is not in use, please cover it to protect the data port.
  4. Use a damp cloth containing alcohol to clean the measuring rod, and do not apply oil to the measuring rod.
  5. Unauthorized personnel are prohibited from disassembling or repairing the digital radius gauge to avoid damage to the instrument.
  6. This instrument does not have waterproof performance. Please keep it dry.
  7. If you need to replace the measuring head, please fix the measuring rod before replacement.