Personalized Insole: 3D Scanning, Foot Casting, and Other Methods for Printing

On November 11th, Alex and I went to the wet lab inside of ME to meet with a graduate student in order to show us how to use the 3D scanner. Alex brought an insole (seen below) that we used to acquire point cloud raw data representing the surface features. It was decided to use the actual insole of the wearer’s shoe to enhance comfort. After using the scanner, the graduate student suggested that we use Geomagic in order to organize the point cloud data to create a 3D model of our design.

The team helped create a foot mold using Alumilite mold and casting resin. After letting the material cure for 20 minutes, Alex removed his foot and let the resign reach full cure (24 hours). We were limited with the amount of casting resin, therefore a plastic bag was wrapped around Alex’s foot to minimize excess volume in order to capture as much of the foot curvature as possible. The next day a casting resin was poured into the mold and  later in the week Alex returned to use the 3D scanner to create personalized support. Now the group is looking to organize the data to create a usable CAD model that we can then use to begin 3D printing.

Some of the challenges with the design that our group has come up with is that traditional FDM beds are not large enough for an insole to be printed on. Alex’s foot was the one measured for this project and he has a size 12 foot which is the equivalent of 11.83″ in length. This is larger than both the print beds of the Flashforge Creator and Wanhoa Duplicator which have print bed sizes of  8.9″x 5.9″ and 7.9″ X 7.9″ respectively. Also that even if a smaller size insole were to be printed on the bed, there is a possibility that the edges would warp without the use of a raft.

So we came up with the idea to print the  insole in two halves regardless of the size. No mechanism is really needed in order to hold the two together because they will be snugly placed inside of a shoe and will not experience any forces besides a downward one from the foot itself. Therefore most likely glue or some form of adhesive will be used to attach the two parts together. The group is considering using gorilla glue in order to adhere the two pieces together, because of the advice from a technical staff member inside the material science department who has worked with adhesives and TPE material before.

Other 3D printing methods that would suit our project would be the use of a binder jetting machine. This would be able to premix materials and give us the different material properties that we are looking for. Right now we are planning on using flexible material in order to create the insole to give the user more comfort and shock absorption. There is currently a type of material that 3D systems offers called VisiJet Colorbond created for binder jetting processes that appears to have some novel mechanical properties that would be well suited for our personalized insole. It is offered in in multiple colors as well in terms of personalization for consumers.