Bristol-based Third Dimension (www.third.com) has launched a countersink measurement solution for its range of GapGun tools.

Said to be the first of its kind on the market, the solution can calculate the dimensions of a countersink hole to accurately predict the flushness of fasteners, once fitted.

Furthermore, it can operate in real time on the production lines of aircraft, cars and vans, as well as in the energy and marine markets.

Last year, in the commercial aviation industry alone, some 1,481 planes were manufactured with an estimated total of 296 million countersinks.

The average requirement is to measure 5% of each aircraft’s 200,000 countersink holes, so 10,000 countersink holes would have to be measured for every commercial aircraft produced.

Done manually, these checks rely heavily on the capability of the operator and are extremely time-consuming; Third Dimension’s patented system takes just a couple of seconds per measurement, with no possibility of operator error.

The GapGun Countersink Inspection System enables fastener flushness to be predicted much faster and more accurately than mechanical gauges — plus there is an auditable data trail.

Moreover, tolerance bands can be pre-set, the measurement recorded against these and the result read on a screen or automatically sent to a PC for comparison and analysis.

Countersinks are notoriously difficult to measure; one of the main challenges for manufacturers is finding a way that considers howto calculate the centre of the hole.

The Third Dimension solution addresses this issue with a specially designed stand-off integrated into the sensor that enables the system to calculate the hole centre and therefore check the required dimensions before the fastener is fixed in place.

The system is based on a single laser line, which contrasts with many other solutions that use multiple laser lines or bars of light.

Third Dimension says multiple laser lines or bars of light produce reflections that degrade accuracy and reliability when measuring the curved inner surfaces of a countersink.

Tolerances for fastener flushness vary; they sometimes allow a small amount of protrusion but always allow under-flush.

For example, one manufacturer known to Third Dimension specifies a tolerance of +0.05/-0.18mm on the final fastener flushness.

The GapGun Countersink Inspection System can predict the flushness within these tolerance bands on most common fastener types.