T3DMC
Image 3 T3DMC coracle
A traditional coracle provide as a point of reference for T3DMC.
In the riverside town of Ironbridge, the Rogers family has been the main supplier of the circular boats, known as coracles, since the early 19th century until Eustace Rogers’ death in 2003. Locals used them when net casting fish and hunting small animals on the banks, when retrieving dead bodies for the local authorities and returning footballs for the nearby Shrewsbury Town FC. In times of flooding, aid has been delivered to neighbours via coracle.
Through the generations, the makers and users of the coracles have etched their legacy into the history of Ironbridge, which derives its name from a 240-year-old cast iron construct, stretching across the river to connect two sides of the settlement. Between 2017 and 2018, the bridge was the focus of a 3.6 million GBP English Heritage restoration project, and now the history of the coracles that sailed underneath it is being marked too.
Driving the project is the Ironbridge Coracle Trust (ICT), who commissioned The 3D Measurement Company (T3DMC) to assist in the reverse engineering of a legacy coracle. T3DMC is a measurement and scanning service provider based nine miles away in Bridgnorth, and boasts a portfolio of eight portable 3D scanning systems. It applies these products, as well as distributing some of them, in accordance with its clientele’s requirements within the automotive, aerospace, power generation and medical markets.
With the coracle, T3DMC explored two data capture methods, using a laser scanning system or leveraging its structured light equipment. Taking stock of the coracle’s delicacy, the company decide to harness ScanTech’s Axe system, a handheld, non-contact, laser scanning device with integrated photogrammetry.
“If you apply any pressure to it, it will change shape or distort, so we had to use our experience from an application standpoint to understand what’s the best way to measure this component without touching it, making sure it keeps its true shape,” Adam Stanley, T3DMC’s Managing Director told TCT. “Laser scanning equipment deals better with uncooperative surfaces than structured light systems do. We didn’t want to potentially damage or permanently mark the coracle, so the laser scanning system was the perfect solution.”
T3DMC
T3DMC coracle
T3DMC scans a modern coracle.
The Axe system boasts 420 mm measurement volume, a 500 mm depth of field, and accuracy up to 0.02 mm, while the photogrammetry function allows the user to create a 3D point cloud which positions all of the scan data accurately. It also dealt with the coracle’s dark colour better than a structured light system would, T3DMC able to scan the boat with just a few reference stickers, rather than spraying a solution to lighten the contrast of the surface. Meanwhile, an intelligent feedback mechanism within ScanTech’s ScanViewer software assisted in making sure the user was in the ‘sweet spot’, just the right distance from the coracle to achieve optimum capture rate and accuracy.
The data is now in the hands of ICT, who will prototype a coracle with 3D printing, and with some additional financial backing, look to get it manufactured via bronze casting. It is a step change from the Rogers family sourcing local timber, calico, and tar or bitumen to manufacture the boats, but one that will help commemorate their imprint on Ironbridge’s history.
For its last 80 years, the family operated out of a small shed in eyeshot of the Iron Bridge. They could have your coracle, manufactured per your height and weight, to you within a fortnight. A strap was attached to the bench to allow people to carry them from destination to destination over their shoulders. The coracle was, for a long time, the enabler in feeding families. It will always be a piece of historical engineering.
With adequate funding, the Rogers’ family shed is to be restored and opened as the final stop on an Ironbridge heritage trail, with the reverse engineered coracle as its centrepiece.
