This week we worked to update the initial prototype and fix some of the initial problems such as the finger caps not fitting tight enough and the resistance bars bending sideways. The finger caps were remodeled in solidworks to include a flat top to better fit the finger. The updated print of this can be seen in figure 1 below (the two new models are on the right). We also redesigned and reprinted the resistance bars to be square so they bend and not rotate as the finger bends.
We also began the process of editing the palm brace. For the next and hopefully final round of prints we will include attachment spots for resistance bands connecting to the middle, ring and pinkie fingers as well as topology optimization to reduce print time and material while keeping the strength of the part. We are also moving the connection location for the pointer finger slightly to the side of the finger so that as it bends the resistance bar doesn’t force the cap off the finger. The finger caps are being updated for a final time so that the connection port to the resistance bar is on the side of the finger. This will keep the cap from rotating as the fingers are bent.
Finally, the resistance bars were printed with 50% infill and proved to show much greater resistance than the initial prints which only had 20%. Once the final design is complete, we plan to have at least two different resistances to show our concept of easily interchangeable bars of different resistances.
Figure 1. Old and new finger cap prints
Here are the specs for this weeks print:
Print 6 4/10/2017
Type: CPE with Natural PVA as support
Part:Finger tip attachment index 2
Finger tip attachment thumb 2
Resistance bar index 2
Resistance bar thumb 2.1
Density: 50%
Support: enabled
Build plate temperature: 75 C
To increase adhesion
Print time: 2 hr 31 min
Quality: Normal quality
Figure 2. Cura screenshot of updated resistance bars and finger caps ready for printing