Dakota Ultrasonics MiniMax v2.0

Dakota Ultrasonics MiniMax v2.0

A bolt tension monitor that can measure the elongation very accurately in fasteners of virtually any material



The Mini-Max v2.0 Ultrasonic Bolt Tension Monitor defines state of the art in the measurement of the actual elongation produced by tightening a threaded fastener. Mini-Max can measure the elongation very accurately in fasteners of virtually any material from 1/2 inch to 4 feet in length. The measurement is achieved by determining  the change in the transit time of an ultrasonic shock wave along the length of the fastener, as the fastener is tightened by any method. 

The on-board microcomputer automatically interprets this time measurement to display the time(nanoseconds), elongation, load, stress or strain from stretching a fastener.  Through the use of high speed digital signal processing and automated diagnostics, the Mini-Max minimizes the requirement for extensive operator training.  With built in data recordation and reporting through Direct USD-C 1.1 PC connectivity, the Mini-Max offers an easy to use and reliable solution to the most difficult bolting problem.


  • Setups: 64 custom user defined setups; factory setups can also be edited by the user.
  • Auto Set: Automates the detection, scope and display setting process for each individual bolt.
  • Alarm Limits: Adjustable Hi/Low tolerances with visual LEDs and audible beeper.
  • Field Calibration: Vector or Regression correction curve for increased accuracy using Load & Stress.
  • Alarm Limits Bar: Hi & Lo alarm limits for displaying an acceptable tolerance range
  • Certification: Factory calibration traceable to NIST & MIL-STD-45662A
  • Warranty: 2 year limited

Bolt Testing Kit Selection Criteria:

1)  Probe Selection:

  • Frequency
    2.25 MHz is food for flange situations
    5 MHz is good for general structure
    10 MHz is good for small diameters

  • Diameter

    Select largest diameter that will fit the bolt end while remaining in complete contact
    For 1/2" to 1 1/4" Diameter Bolt, use 3/8" or 1/2” Diameter Probe
    For 1/8" or 1/4" (with head) Diameter Bolt, use 1/8" Diameter Probe

*Transducers are not included and need to be purchased separately


  • Magnetic or Non-Magnetic
    Magnetic probes are recommended for testing steel bolts
    Constant and repeatable contact with part
    Hands-free inspection
  • Glue-On Single Contact Crystals

    In cases where it is difficult to place/mount a standard transducer; the Glue-On Single Contact Crystals are a good option. Glue-on transducers also ensure correct transducer placement. For use on fasteners with limited elongation.

Magnetic Single Element Contact Transducers

2) Application Questions:

  • What material types are you testing?
  • What are the minimum and maximum diameters and lengths of bolts?
  • What type of bolt? Stud or bolt with head?
  • Do you plan on measuring the same bolt over the service life of the bolt (measuring periodically, more than once)?
  • Are there any raised grade markings on the heads of the bolts? If yes, they need to be ground flat or contact us to further discuss a custom transducer.
  • Do you expect to experience any bending in the joint your fastening? This can commonly occur in flange joints. 2.25MHz is better for flange situation - more forgiving of the bending).

3) Calibration Bar Set

Used for monitoring the bolts over the service life. Not required if not monitoring bolts over service life or using more than one gauge.

4) Temperature Sensor

Required if measuring results at different temperatures. 


*See following link for a full list of probe options: Transducer List

*Contact us Here for further review if you are not sure with transducer is right for you

Non-Magnetic Single Element Contact Transducers

Technical Specifications


  • Weight: 13.5 oz. (with batteries)
  • Size: 2.5" x 6.5" x 1.24" (63.5 x 165 x 31.5 mm) (W x H x D)
  • Operating Temperature: 14° to 140°F (-10° to 60°C)
  • Keyboard: Membrane switch with 12 tactile keys
  • Case: Extruded aluminum body with nickel plated aluminum end caps (gasket sealed)
  • Environmental: Meets IP65 requirements

  • USB: Direct USB-C 1.1 PC connectivity. Windows & OSX interface software.
  • Line Power: USB-C to PC or AC adapter
  • Temperature Sensor: 5 pin Lemo 1
  • Transducer Connector: Lemo 00

  • Log Format: Grid (Alpha Numeric)
  • Capacity: 4GB internal SD memory.
  • Screen Capture: Tagged interface file (.tif) capture for quick documentation
  • Custom Setups: 64 user configurations
Power Source

  • Line Power: USB to PC or power outlet
  • Batteries: 3 AA cells.
  • Alkaline 35 hrs, Nicad 10 hrs, NI-MH 35 hrs.
  • Auto power off after 5 minutes idle.
  • Battery status icron

  • Transducer Types: Single element - 1 MHz to 10 MHz frequencies and 1/8" to 1" diameters.
  • Glue-On: Available for short bolts with minimals / short elongations to eliminate transducer placement errors.
  • Connectors: Microdot, Lemo 00 or BNC options depending on the transducer model selected.
  • Custom Transducers: Available for special applications
  • Temperature Probe: Automatic temperature compensation

  • Display: 1/8" VGA grayscale display (240 x 160 pixels); viewable area: 2.4" x 1.8" (62 x 45.7 mm); EL backlit (on/off/auto invert)
  • A-Scan: Rectified +/- (half wave view) or RF (full waveform view)
  • Large Digits: Digital display only
  • Screen Refresh Rate: 30 Hz
  • Timing: Precision TCXO timing with single shot 100 MHz 8 bit ultra low power digitizer
  • Pulser Type: Square Wave
  • Pulser Voltage: Selectable 100, 150 and 200 volts
  • Pulse Width: Selectable options Spike, Thin and Wide. 80 to 400 ns.
  • Damping: 50, 75, 100, 300, 600 & 1500 ohms
  • Frequency Band: Broadband 1.8 - 19 MHz (-3dB) filter
  • Horizontal Linearity: +/- 0.4% FSW
  • Vertical Linearity: +/- 1% FSH
  • Amplifier Linearity: +/- 1 dB
  • Amplitude Measurement: 0 to 100% FSH, with 1% resolution
  • Delay: 0 - 999.9" (25,400 mm) at steel velocity
  • Measurement Gate: 1 gate with audible and visual alarm. Amplitude 5 - 95%, 1% steps.

  • Units: English (in), Metric (mm) or Time (µs). Farenheit or Centigrade.
  • Velocity: 0.0492 to .5510 in/µs (1250 - 13995 m/s)
  • Measurement Modes: Pulse-Echo (P-E)
  • Measurement Range: 1" to 50 ft. (25.4 mm to 15.24 M), dependent on material type and consistency.
  • Detection: Zero Crossing
  • Resolution: +/- 0.00001" (0.0001 mm)
  • Calibration: Automatic, Fixed, Single or Two-Point zero calibration options
  • Quantities: 
    • Time: Nanoseconds
    • Elongation: Change in length (inches/millimeters)
    • Load: Force load applied (pounds KIP or megapascals MPa)
    • Stress: Force for unit area stress applied (inches per inch or millimeter per millimeter)
    • %Strain: Ratio of elongation to effective length
    • Bolt materials: Select types from a preset or custom list)
    • Repeatability Bar Graph: Bar graph indicates stability of measurement

Kit Includes

MiniMax Instrument Kit

  • MiniMax v2.0
  • 3 AA Batteries
  • 4 oz. Bottle of Couplant
  • USB Type A to Type C Transfer Cable
  • Carrying Case
  • 10’ Lemo to Microdot Transducer cable
  • PC Utility Software (download from website)
  • Operation Manual and Certification.

*Transducer Not Included - Purchase Separately

Product Literature

Description Part # Saved Price Select Option Add to
MiniMax Kit Includes new version 2.0 hardware platform, and temperature connector for use with part# A-156-8001. - External temperature source used, or user will be measuring fasteners one time only. UT-DU-Z-156-0006 $3,850.00
Magnetic Single Element Transducer, 5 MHz, 1/4", Microdot, Top Mounted, T-702-2405 UT-DU-T-702-2405 $765.00
Magnetic Single Element Transducer, 2.25 MHz, 3/4", Microdot, Top Mounted, T-706-1405 UT-DU-T-706-1405 $840.00
Dakota Ultrasonics Contact Transducer, 1/2" Diameter, 2.25 MHz, Top Entry and Microdot Connector, T-5043-1855 UT-DU-T-5043-1855 $320.00
Temperature Probe UT-DU-A-156-8001 $525.00
3" & 6" Steel Calibration Bars UT-DU-X-000-0010 $575.00
3" Steel Calibration Bar 4140 Steel UT-DU-X-000-0011 $325.00