Extensometers for materials testing

High Elongation Extensometers – Model 3800

Designed for plastics, rubber and elastomer testing, these extensometers have very long measuring ranges. Their unique design allows testing to failure and minimizes interaction with the sample.

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.


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

36 EXTENSOMETER MODELS are available in many thousands of variations. Our focus on helping customers has led to the development of models to cover nearly any test method.

The main body of this unique extensometer remains stationary during testing, held in position by the adjustable magnetic base included. Only the very light, small traveling heads move as the sample elongates during a test. These attach to the sample with small spring clips. Each head pulls a cord out from the extensometer as the head moves.

These models use high precision, low friction potentiometers, and, as a result, have a wide range of factory selectable outputs. The extensometer is driven by an excitation voltage and has output proportional to the input. They can be provided with high level outputs (approximately 2-8 VDC) or ones that mimic strain gaged devices (2-4 mV/V). When set to mimic strain gaged extensometers, the Model 3800 can be used with virtually any signal conditioning electronics designed for strain gaged sensors. The potentiometers employ a hybrid wire wound around conductive plastic, which provides excellent long term stability. The output from the extensometer is readily interfaced with most existing test controllers and may be directly input to data acquisition systems and chart recorders. Please let us know at the time of order what type of output and connector you require.

Download Data Sheet

  • May be left on through specimen failure.
  • Applicable for testing to ASTM D412.
  • The main body is stationary with only the lightweight traveling heads moving.
  • Comes with an adjustable magnetic base for easy mounting.
  • Large measuring range to 500 mm (20 inches).
  • Includes the Epsilon Shunt Calibration System (with units configured to mimic strain gaged sensors) for on-site electrical calibration.
  • Includes high quality foam lined case.
  • Low cost, high accuracy elastomer strain measurement.

Download Data Sheet

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

Output: Either 2 to 8 VDC, depending on model (at 10 VDC input) or 2 to 4 mV/V, nominal, selectable at time of order

Accuracy: ±1 mm (±0.040 inches)

Resolution: 0.2 mm (0.008 inches)

Temperature Range: -40 °C to 100 °C (-40 °F to 210 °F)

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

Operating Force: 80 grams typical per head



Download Data Sheet

  • Can be provided with either:
    • High level outputs (approximately 2-8 VDC)
    • Output that mimics strain gaged devices (2-4 mV/V nominal)
  • 2 mV/V output for use with electronics designed for strain gaged sensors.

Download Data Sheet

Product Videos

Demonstration: tension test of a rubber material per ASTM D412 using the Model 3800 extensometer.

Setup instructions for the Model 3800 extensometer.

Ordering Information

Click table options to configure

Gauge Length i

mm or inches #
20.0 mm -020M 020M
25.0 mm -025M 025M
50.0 mm -050M 050M
1.000 in -0100 0100
2.000 in -0200 0200

Measuring Range i

extension #
+250 mm -250M 250M
+500 mm -500M 250M
+10.000" -100T 100T
+20.000" -200T 200T

Model Number:  3800_ _ _ __ _ _ _

Model Number:

3800_ _ _ __ _ _ _

Model 3800 Available Versions: ANY combination of measuring ranges and gauge length listed above is available. Available in intermediate and larger gauge lengths on special order.

Example: 3800-0100-100T: 1.0 inch gauge length,+10 inches measuring range (+1000% strain), temperature range of -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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Our 2020 Extensometer Catalog, Version 110 is now available! Not finding something you’re looking for? Ask us about a custom quote.