While 3D printed prosthetics have been gaining a lot of attention lately, there have been a myriad of other applications where additive manufacturing has helped lower the cost of creating custom products for the human body. Additionally, various 3D modeling software makes it easy to adjust sizes at literally the push of a button before printing.
Among others who have explored 3D printing custom products is Leo Connelly. Along with a group of classmates at the NUVU school in Cambridge, Massachusetts, Connelly developed an exoskeleton cycling shoe that was created specifically for beginner triathletes who may not be interested in purchasing top-of-the-line cycling shoes for the run, swim and bicycling competition that can run into the hundreds of dollars.
Among other benefits of the 3D printed shoe, it can be manufactured within hours, can be adjusted to fit a wide range of pre-existing running shoes, can be easily swapped during the heat of a triathlon competition and can provide the full experience of wearing a traditional cycling shoe at a fraction of the cost.
According to Connelly, some athletes never purchase cycling shoes because they don’t feel the need to change shoes for more performance, yet his 3D printed exoskeleton design ensures that the athletes won’t have to make that decision at all.
To start their project, Connelly and team brainstormed ways that they could make existing athletic shoes easier to use. One group member - who had previously been to a triathlon - recalled watching athletes transition from biking to running with hardship due to swapping their shoes while in a race against time.
Using this as a backbone for their project, the team soon discovered that an exoskeleton ‘slipover’ shoe would be a perfect ‘middle-ground’ between an athlete’s existing running shoe and their bicycle pedals.
To develop their concept, the team jumped into the McNeel Rhino suite of 3D modeling tools including T-Splines and Grasshopper.
“From the cusp we broke up into factions,” said Connelly.
“Jesse became the sketcher, creating sketches on paper and on Rhino that would be put into T-Splines, Max became the "T-Spliner", creating the shoe and the 3d model on Rhino using T-Splines; a Rhino based software that allows for easy morphing, and Leo became the "grasshopper", creating a way to adjust the size of the shoe in order for the user to change sizes easily.”
Among other factors that were driving their exoskeleton shoe design, the team wanted the additive manufacturing process to be as streamlined as possible so that an athlete could simply enter their shoe size into the software and all design updates would be generated automatically for a 3D print. By approaching the project with this in mind, the team would only have to 3d model the exoskeleton shoe once and simply resize the model from person to person automatically.
To determine the best design direction for the shoe, the team worked simultaneously in Rhino while also developing their first physical prototype using cardboard. It was later determined that the two biggest influencers of their design would be how the exoskeleton would fit to existing running shoes as well as how the shoe will lock to a cycling pedal. Once these design drivers were executed in Rhino, the team decided at this point to make their first 3D print.
While their first 3D print reflected their design intent including slits for Velcro straps and a connection for the bike clip, it was too small to test due to the limitations of the 3D printer’s build platform size. To solve this, the team broke the exoskeleton model into two separate printable parts.
“We were only able to print one half of it to begin with, but it was enough to realize that we had created a usable, shoe like product that one could not only be stepped into, but walked around in,” added Connelly.
The design also had the capability to lock into an actual bike pedal - impressive for a 3D print. Unlike their first iteration however, this prototype proved to be too big based off of a Rhino scaling error. Once they pinpointed where the scaling mistake occurred, all that was needed was to scale it back down for their third and final 3D print.