340 E-Computer


The Model 340 E-Computer measures material properties of a wide range of materials and sizes.

  • Provides accurate, repeatable measurement of modulus of elasticity (E) without measuring deflection
  • Automatically computes specific gravity and weight
  • Saves digital data for convenient processing
  • Compact, portable design allows set up for use in just minutes
  • Quick and easy to use

The Model 340 E-Computer includes one electronic interface unit, two tripod assemblies, one calibration weight, one software module on disk, one load cell, and connector cables necessary for connection to RS232C serial port of customer’s personal computer. Also included is a carrying bag for the tripods, load cell, cables, and test weight. Note: This system does not come with a personal or notebook computer. E is computed from measured values of weight (W), vibration frequency (f), and “dial-in” values of width (b), thickness (h), and span length (l). K is a calibration constant. Then, E = (W I3 f 3 )/ (K b h3.)

  • Model 340 operates with a personal computer (not included) to determine material properties of a specimen simply supported as a beam
  • This equipment can help you determine E and specific gravity for wood specimens with a wide range of sizes.
  • Quick and precise, and eliminates the need for deflection measurement.
  • With a test specimen supported by the test tripods and the load cell tripod connected to the Model 340 electronics unit, vibrations are initiated usually by gently striking the specimen by hand near the span center. Measurements are taken as the resonant vibration decays.
  • The Model 340 electronic interface unit connects by cable to your personal computer (PC), into which the Model 340 E-Computer software is loaded.
  • Information about the test specimen and operating parameters is input to the PC via the keyboard. Results are displayed on the PC monitor, and data is recorded on the PC disk drive(s).


Requires a windows PC with a Serial or USB to Serial adapter


Modulus of Elasticity

Computed from specimen dimensions and load cell signal.

Specific Gravity

Computed from weight at condition of test and specimen dimensions.


Computed E is compared with operator-selected grade thresholds; resultant grade is displayed on screen and recorded with data file.

Electronic Interface

Provides excitation and demodulation of load cell signal, and conversion to serial data stream for transmission to computer through a standard RS232C port. Includes cables for ac power, plus a load cell, control wand, and connection to computer serial port. No internal PC modifications are required.

Five specimen weight ranges provide the sensitivity required for testing the smallest dimension lumber specimens plus the range required to test large laminated and composite specimens. Standard specimen weight range is 25 to 250 lbs (111-1112 N).


110 Vac 60 Hz, 1 Amp (220 Vac, 50 Hz optional)


11 lb (5 kg)

Dimensions (LxWxH)

7 x 10 x 10 in (180 x 250 x 250 mm)

Shipping Container

16 x 16 x 16 in (410 x 410 x 410 mm)

Shipping Weight

15 lb (6.8 kg)

Tripod Test Fixtures

Load cell and free-edge vibration fixtures are conveniently mounted on tripod supports with removable legs.


30 lb (14 kg)

Tripod working height

37 in (940 mm) with legs attached. Test fixtures can be used without their legs for heavier specimens.

Control Wand

Hand control for operating E-Computer electronics;. Connects to electronic interface by cable.

System Shipping Dimensions

Shipping Container (LxWxH)

16 x 41 x 13 in (410 x 1040 x 330 mm)

Shipping weight

. 60 lb (27 kg)

Aluminum Calibration Test Bar


This test bar simulates a wooden 2 x 4 (1.5 x 3.5 in 38 x 89 mm), with an E of 2.24 x 106 psi (15.5 GPa), for calibration purposes.

Size 1 x 2.5 x 96 in (25.4 x 63.5 x 2438 mm)
Alloy 2024-T351 aluminum

Brass Test Weight


Brass test weight is used to calibrate the gain of the load cell system. After laboratory calibration with both test bar and test weight, only the lighter, less bulky test weight needs to be carried to the field.


8 lb (3.6 kg)

Production line Interface


Provides hardware and software components for adapting the basic Model 340 E-computer (required) to customers lumber grading production line. Includes optically coupled solid state relay inputs and outputs for interfacing to customer’s grading line control system. Customer controls lumber, lumber vibration and provides signal input to 340 E-computer to start measurement and E computation. Software determines E and grade and puts out digital output signals to customer’s control system.