Design Progress
Milestones
Timeline
Read about our progress milestones starting in September of 2024 and what we have planned for the future.
Outer Socket
Spring:
April - June 2025
Coming Soon!
Winter:
January - March 2025
Overall Socket Shape:
After having the wall of the previous outer socket completely sheared, we decided to increase the wall thickness of the outer wall to 3 mm while also adding fillets to the interface between the walls and the base. We are also working towards making a parametric model of the outer socket.​​
​
Pyramid Adapter Attachment:​
​After experiencing issues with the 4-hole male pyramid adapter's interface with the outer socket, we decided to proceed with the threaded male pyramid adapter instead. This system involves a metal disc that meshes with the outer socket base using strong glue and has internal threads to mesh with the pyramid adapter. This would allow us to reuse the expensive titanium pyramid adapter more easily.
​
Strap Design:
We realized that there were issues with the attachment of the buckles to the outer socket wall due to the low surface area of the metal buckles. We determined that the best process moving forward would be to embed strap holders within the 3D-printed socket itself (see prior designs) while still utilizing pack straps instead of our original velcro straps.
Fall:
September - December 2024
Understanding the drawbacks of previous designs, we opted to scrap them and come up with a new design.
​
Overall Socket Shape:
-
Overhauling previous designs due to inflexibility, we moved towards a new, “petal” design with three removable socket walls. However, we soon realized that removable petals were not structurally sound and included a very involved process to fit an individual’s leg.
​
-
We then designed a socket with non-removable petals, with three petals based on an example Patellar-Tendon-Bearing (PTB) Socket model. We determined that a three-petal design would result in the best balance between an adjustable fit and good structural integrity. We also determined that having a petal covering the entire patellar area of the stump would result in better support due to most of the load being placed in that area.
​
-
After printing the socket model with PLA and a wall thickness of 2 mm and height of 8 in, we were impressed with the flexibility of the socket walls when under compressive force exerted around the circumference of the socket. However, after daily use, one of the walls (due to there being no fillets along the attachment between the walls and the base) sheared off of the base of the socket.
​
-
We were also able to fabricate two non-petal sockets with varied wall thicknesses for testing purposes. We were impressed with the stability of the 2 mm wall thickness socket, even when compared to the 4 mm wall thickness socket.​​
​
​Pyramid Adapter Attachment:
-
Initially, we determined that the 4-hole pyramid adapter would give us the best interface with the 3D-printed socket due to the increased surface area compared to the threaded pyramid adapter.
​
-
Our design consisted of 4 flanged metal inserts placed during the 3D-printing process of the outer socket base. The pyramid adapter would then be attached to the base with flat-head screws that were screwed into the metal inserts and would be glued to the socket base.
​
​Strap Design:
-
Our initial strap design to compress the flanges of the outer socket inward consisted of a ski-boot strap attachment. However, the part complexity and cost of the ski bootstraps led us away from this approach. We then moved toward velcro straps with metal buckles that would be glued externally to the socket.
Inner Socket
Winter:
January - March 2025
Overall Socket Shape:
The inner petal design consists of poron foam which is used to build pressure around the pressure-sensitive areas of the transtibial stump to distribute the load. We started with soft foam for the base layer, and then cut pieces for the areas around the pressure-sensitive areas (refer to the load distribution image below). Additionally, the top is layered with a thin piece of hard foam to create a smoother finish. Finally, we rounded out the edges for a more comfortable design.​