Miniature Axial Extensometers – Model 3442

Small profile and ultra-light weight, these units are appropriate for testing small and delicate samples yet rugged enough for daily use on standard specimens. Ideal for strain measurement of wire specimens, sheet materials, and standard ASTM or ISO specimen geometries. Excellent for low and high cycle fatigue testing.

Gen2 Product

Operation of these, and all of Epsilon’s extensometers, are


using in-house calibration systems that are calibrated with Epsilon’s laser interferometer system.


to the materials testing community, you know we will be there to stand behind our products when your critical application requires it.

Epsilon extensometers are COMPATIBLE WITH VIRTUALLY EVERY BRAND OF TEST EQUIPMENT and can be supplied with the correct connector to plug in directly, or supplied with a separate conditioner and amplifier.

Weighing as little as 8 grams, these miniature extensometers are designed to have very low operating force with minimal specimen influence. Their low mass makes them the optimum choice for fatigue testing in strain control and high-frequency testing.

Suitable for tension or compression testing, all configurations use an improved version of Epsilon’s dual flexure design which makes them very rugged for their size. With a compact module that is 15.2 mm (0.6 inches) high, they will fit in the limited space between grips that is typical with small test samples.

Gauge lengths can be as short as 3 mm or as long as 50 mm. A newly designed gage setting pin and assembly allows the gauge length to be set accurately and repeatably to ASTM and ISO requirements for all gauge lengths. Reengineered quick attach wire forms provide simple and secure specimen attachment. Wire forms for round and flat specimens are included, as well as knife edges in flat, 3-point, and vee configurations. The wire forms may be removed to enable mounting using elastic bands or springs. A tethering attachment point provides fall protection and enables counterbalancing of the extensometer’s weight when testing delicate specimens.

Model 3442 extensometers are strain gaged devices, making them compatible with any electronics designed for strain gaged transducers. Most often they are connected to a test machine controller with electronics for a strain channel, and Epsilon will equip the extensometer with a compatible connector wired to plug directly into the controller. For systems lacking the required electronics, Epsilon can provide a variety of solutions for signal conditioning and connection to data acquisition systems or other equipment.

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  • May be left on through specimen failure in most applications.i
  • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
  • Gauge length pin helps set gauge length accurately for all gauge length configurations.
  • All models can measure in both tension and compression and can be used for cyclic testing.
  • Mechanical overtravel stops in both directions.
  • Rugged, dual flexure design for strength and improved performance. Much stronger than single flexure designs, this also allows cyclic testing at higher frequencies.
  • Gauge length adapter kits enable configuration of multiple gauge lengths with one extensometer.
  • Replaceable arms and spacers for ease of repair.
  • High and low temperature options extend operation from as low as -270 °C to +200 °C (-454 °F to +400 °F).
  • Includes the Epsilon Shunt Calibration System for on-site electrical calibration.
  • Includes high quality foam lined case.

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Excitation: 5 to 10 VDC recommended, 12 VDC or VAC max.

Output: 2 to 4 mV/V nominal, depending on model

Accuracy: Standard configurations meet ASTM E83 class B-1 accuracy requirements for gauge lengths ≥6 mm and class B-2 for ≤5 mm. All standard configurations meet ISO 9513 class 0,5. A test certificate is included.

Linearity: ≤0.15% of full scale measuring range

Temperature Range: Standard (-ST) is -40 °C to +100 °C (-40 °F to 210 °F)

Cable: Integral, ultra-flexible cable, 2.5 m (8 ft) standard

Standard Quick Attach Kit: Fits round samples 0.5-13 mm (0.02-0.5 inch) diameter and flats 0.1-13 mm thick by up to 15 mm wide (0.005-0.5 inch by up to 0.6 inch); attach to larger specimens using rubber bands or springs (included)

Operating Force: Depends on model configuration; 10 to 100 g typical



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  • Adapter kits to change gauge lengths
  • Connectors to interface to nearly any brand of test equipment
  • Special coatings and stainless steel knife edges available for biomedical tests
  • Specialty Knife Edges

Download Data Sheet

Product Videos

The Model 3442’s new gauge length pin makes attachment accurate and repeatable. Click above to see a full tensile test demo.

Setup instructions for the Model 3442 extensometer.

Ordering Information

Click table options to configure

Gauge Length i

mm or inches #
3.0 mm -003M¹ 003M
4.0 mm -004M¹ 004M
5.0 mm -005M¹ 005M
6.0 mm -006M 006M
8.0 mm -008M 008M
10.0 mm -010M 010M
12.0 mm -012M 012M
12.5 mm -0125M 0125M
20.0 mm -020M 020M
25.0 mm -025M 025M
50.0 mm -050M 050M
0.250 in -0025 0025
0.300 in -0030 0030
0.500 in -0050 0050
0.640 in -0064 0064
1.000 in -0100 0100
2.000 in -0200 0200

Extension i

extension #  
±0.5 mm -005M 005M
±1.0 mm -010M 010M
+2.0 mm / -1.0 mm -020M 020M
+2.5 mm / -1.0 mm -025M² 025M
+5.0 mm / -1.0 mm -050M² 050M
+10.0 mm / -1.0 mm -100M² 100M
+12.5 mm / -1.0 mm -125M² 125M
±0.050 in -005T 005T
+0.100 in / -0.050 in -010T² 010T
+0.250 in / -0.050 in -025T² 025T
+0.500 in / -0.050 in -050T² 050T

Temperature Range

degrees #
-270 °C to 100 °C (-454 °F to 210 °F) -LT LT
-40 °C to 100 °C (-40 °F to 210 °F) -ST ST
-40 °C to 150 °C (-40 °F to 300 °F) -HT1 HT1
-40 °C to 200 °C (-40 °F to 400 °F) -HT2 HT2
-270 °C to 200 °C (-454 °F to 400 °F) -LHT LHT

Model Number:  3442 – _ _ _ __ _ __ _

Model Number:

3442 – _ _ _ __ _ __ _

Model 3442 Available Versions: ANY combination of gauge length, measuring range and temperature range listed above is available, except as noted. The measuring range should not exceed the gauge length. Other configurations may be available with special order; please contact Epsilon to discuss your requirements.

¹Available in -010M and -020M measuring ranges only; meets accuracy requirements for ASTM E83 class B-2. Gauge lengths of 6 mm or larger are recommended.
²Extended compressive measuring ranges are available – inquire with Epsilon.

Example: 3442-008M-010M-ST: 8 mm gauge length, ±1.0 mm measuring range, standard temperature range (-40 °C to 100 °C)


If your unit is in need of service, calibration or repair, initiate the RMA process with us and we will be happy to assist.

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