The use of 3D printed honeycomb material to pad helmets has been practiced now for years.
But the process continues to be refined. The latest company to do this is London-based Hexr with a bioplastic called Polyamide-11 made from castor bean oil. The honeycomb shape underneath the custom bike helmet offers riders better protection than foam based helmets, according to the company.
Hexr claims that the honeycomb absorbs impact 68 percent more effectively than an ordinary bike helmet. These claims were independently tested at the University of Strasbourg by Professor Remy Willinger, an expert in head injury and helmet design.
Hexr claims it has performed better in velocity and acceleration tests by an average of 30 percent on a sample of over 40 helmets.
While honeycombs can be stiff along the axis longitudinal to the cell, they are relatively weak in the lateral direction, prone to collapse if the honeycomb cell is made of paper, or crumble in the case of plastic, such as Polymide-11. The weakness actually provides a benefit to safety, according to Dr. Willinger, as rapid rotation of the helmet, such as could happen in a crash, is not fully imparted to the skull. The brain is protected to some extent from rapid rotation of our heads by the cranial fluid.
Bottom Line
The Hexr helmet is custom made for a rider’s head after a fitting session where the seated rider dons a fabric “snanning cap” with text on it. A friend uses an iPhone that guides him or her to take a series of photos around you, guiding you with red dots that turn green when the phone is at the proper distance and orientation in a manner that suggests photogrammetry is at work.
The known text sizes on the fabric of the cap helps to get accurate dimensions. Then the company 3D prints the helmet using laser sintering. Each one takes 36 hours to print and costs £299 with free delivery in the UK and £10 shipping within Europe.
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