E1 gauge – Digital crackmeter

Technical specifications

Operating principles of the digital crackmeter

The E1 gauge is a removable digital crackmeter for manual crack monitoring on 1 or 2 axes — also referred to as a digital crack monitor — with a resolution of 0.01 mm and a repeatability of ±0.01 mm. At each site visit, you read the displayed value yourself and record it in the Saugnac.app application.

A patented fixing system

Its patented system uses 2 transparent plates mounted on either side of the crack with the template supplied (3 plates for 2-axis monitoring). Once the gauge has been zeroed on the reference standard supplied, it is positioned in the transparent plates to take the reading.

Weatherproof manufacturing

The plates are made from a material (PA12) that is highly resistant to the elements (rain, sea spray, UV). This material is commonly used for highly exposed parts, such as car headlights, watch windows, boat parts, spectacle frames and control panels.

A system compatible with a high level of offset

Its unique fixing system allows installation configurations with a high degree of offset (up to 35 mm), in corners or on a ceiling, without having to hold the gauge when taking measurements.

A discreet, practical solution

Once the measurement has been taken, only the transparent plates remain on the surface. Each pair of plates supplied has a QR code and a unique identifier so that measurements can be tracked using the Saugnac.app application supplied.

The digital crackmeter case

The E1 gauge is supplied in a quality case for easy storage and transport, containing:

– a carbon reference standard with a very low coefficient of expansion (3.5 × 10⁻⁶) for zeroing before measurement. Each standard is individually measured and its value marked on its body, so that readings can still be compared if the standard is ever changed.

– a 1-axis installation template

– a 2-axis installation template

– 5 pairs of P1E1 plates with impact anchors, for monitoring 5 cracks on 1 axis

– detailed instructions

How to fix the digital crackmeter plates?

The plates are fixed on either side of the crack and are used to position the E1 gauge during measurement. The plates are transparent and therefore barely visible. They are less than 10 mm thick, so they take up very little space. The PA12 material used guarantees high resistance to weathering (rain, UV) without deterioration.

Fixing is mechanical, using the Ø 4 mm impact anchors supplied. Each plate has a Ø 4 mm hole in the centre, which makes mechanical fixing straightforward. Ø 4 mm holes 30 mm deep must be drilled at the marks obtained with the installation template supplied.

The 4 mm diameter makes it easy to drill the hole on any surface. Simply pass the impact anchors through the plate into the hole, tap with a hammer, then finish with the PZ1 screwdriver. A Bosch SDS Ø 4 mm drill bit and Stanley PZ1 screwdriver set is available to make installation easier.

It is also possible to bond the plates in place using a fast-curing epoxy adhesive. This adhesive holds after 4 minutes, but its final cure takes 2 hours: wait until then before taking the first measurement, so that the plates can no longer move. Since the resolution of the E1 gauge is one hundredth of a millimetre (0.01 mm), repeatability at that level depends on the quality of the fixing.

How do you measure the change in the opening of a crack with the E1 gauge?

Manual monitoring of a single-axis crack with the E1 crackmeter is simple. At each site visit, you take the reading yourself.

1 – Fixing the pair of plates

First, the pair of 1-axis plates (P1E1) must be fixed on either side of the crack (see above). 5 pairs of P1E1 plates for 1-axis tracking are supplied with the E1 gauge, and boxes of 5 pairs of P1E1 plates can be purchased to monitor further cracks.

2 – Zeroing the digital crackmeter on the reference standard

The crackmeter must then be zeroed on the reference standard supplied: the E1 works by comparative measurement against that standard. Always zero the gauge on the standard before taking a measurement on the plates. We recommend carrying out this operation directly in the case, so that the standard lies flat.

3 – Taking the measurement

Position the crackmeter in the plates and take the measurement. The difference between two measurements gives the evolution of the movement. You then record the reading manually in the Saugnac.app application. For reliable results, we recommend releasing any mechanical stress after each positioning and systematically taking three consecutive measurements, then calculating their average.

4 – Monitoring the evolution of the crack

Measurements are easily tracked in the Saugnac.app application. Each plate supplied has a unique QR code, which makes measurements traceable by associating a measurement history with a given plate.

How do you measure a crack in a corner?

The E1 fixing system allows the gauge to be fitted in corners. The 1-axis installation template supplied can be used to determine the reference points for angled mounting. Simply position the gauge in the plates to read the measurement and transfer the values to the Saugnac.app application.

How do you measure a crack on 2 axes (opening + shear)?

The E1 crackmeter can monitor cracks along 2 axes, that is, both crack opening and shear. This may be the case, for example, where the ground has partially subsided (illustrative example on the left).

To monitor a crack or a movement of this type, use the E1 gauge together with the P2E1 plates for 2-axis tracking and the Saugnac.app application, which performs the calculations.

The P2E1 plates work in the same way as the P1E1 plates (identical fixing and positioning), but are supplied in sets of three.

Using the 2-axis template supplied, the P2E1 plates are fixed at the 3 points A, B and C. Measurements AB, AC and BC are taken the first time. Subsequent measurements are taken only on AB and AC, since BC does not vary.

The Saugnac.app application projects these values into an orthonormal X,Y reference frame and derives the movement on those 2 axes. The corresponding X,Y reference frame is shown on the template so that it can be identified without ambiguity. We recommend taking a photo of the plates with the template in front of you, to clearly identify plates A, B and C as well as the X and Y axes — it makes later measurements and their interpretation easier.

Any position is possible (vertical, horizontal, oblique or angled crack), by positioning the template according to the crack. Example of positioning the gauge and plates to follow an angled crack on 2 axes:

Download the Saugnac.app application to monitor your measurements

The Saugnac web application, completely free and with no restrictions, is available on PC or smartphone from https://saugnac.app. Thanks to the unique identification of each pair of P1E1 plates (for 1-axis tracking) or set of three P2E1 plates (for 2-axis tracking), manually recorded measurements can be associated with each survey point. The application allows you to:

– save measurements in your space
– retrieve temperature and humidity levels using geolocation
– calculate variations on 2 axes (X and Y)
– work with several people on the same gauge
– manage alert thresholds
– classify gauges by location and locate them on a map
– download data in Excel format
– automatically display graphs
– share data with others without an account
– access the application from your PC or smartphone
– add measurements without a connection, in offline mode

Find out more about how the application works.

Frequently asked questions about the E1 crackmeter

Does the E1 transmit measurements to the app automatically?

No. The E1 is a removable crackmeter for manual reading. You take each measurement yourself on site, then record the reading in the Saugnac.app application. There is no automatic data collection or transmission. For remote monitoring with automatic readings, the R1 wireless crackmeter is the product designed for that purpose.

What is the difference between the E1 and the R1 wireless crackmeter?

The E1 is designed for manual crack monitoring: you measure yourself at each site visit and get a digital readout with 0.01 mm resolution. The R1 measures continuously and transmits data automatically over an LTE-M / NB-IoT module, which suits hard-to-reach structures and long-term monitoring.

How accurate is the E1 crackmeter?

The E1 offers a resolution of 0.01 mm and a repeatability of about ±0.01 mm under ideal conditions and with perfectly reproducible handling. This level of precision makes the device sensitive to the slightest variation in positioning and handling: repeatability therefore depends on the quality of the plate fixing as well as on careful, consistent measurement. We recommend releasing any mechanical stress after each positioning and systematically taking three consecutive measurements, then calculating their average.

Can the E1 monitor a crack on two axes?

Yes. Combined with the P2E1 plates, it can measure both the opening and the shear of a crack. The Saugnac.app application then derives the movement in an orthonormal X,Y reference frame.

Can the E1 be used in corners or with a high level of offset?

Yes. The patented fixing system allows installation in corners, on ceilings or with a high degree of offset (up to 35 mm), without having to hold the gauge when taking measurements.

Is the E1 suitable for outdoor use?

Yes. The transparent plates are made from PA12, a material that is particularly resistant to the elements (rain, UV), making them suitable for both indoor and outdoor applications. The gauge itself, however, is a removable measuring instrument that is not intended to remain outdoors: after each reading, it is removed from the plates and stored in its carrying case. Only the transparent plates stay in place on the surface.