After much hard work the group was able to assemble the Shear Bioreactor Prototype! Right in time for our final presentation tomorrow.
The working prototype mechanism of action:
(Please click on the picture if the gif does not load)
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I hope you enjoyed the journey as much as we did!
-2013 DTE Team:
Grace, Mitch, Kevin, & Ben
We got the forks back from the Zahn center and (after some filing done by Grace) they are looking good!
We are continuing to machine the base parts/arm and are beginning the final assembly.
The order was successfully given to Arthur and put into the Zahn Center for paddle/tissue fork 3D printing. Our initial meeting them was extremely helpful and we learned to include more tolerance to allow the tissue forks to move in and out of the holder.
We also began the machining process after receiving the cut pieces from Phillip and his lab.
We have received all of the materials that we ordered from Adafruit (Arduino accessories) and McMaster Carr. There was some confusion (as there sometimes in with many parts and multiple vendor orders) and some parts were missing/incorrect sizes. After some exchanging and re-ordering, all of the correct parts arrived.
We then composed a Gnantt chart to document what tasks we have left and what pieces needed to be assembled/machined. We considered the available resources and made decisions of what machining we could manage ourselves (with help from Pete, of course), what parts Phillip Cook could make, and what we would have to outsource to the Zahn center.
We decided that Phillip Cook and Brian would do the initial base cuts (we ordered double the size of the bases needed so we would have a spare) of the two large base pieces and the actuator arms. The Zahn center would 3D print the paddles and tissue forks. Pete and the gang would make drill holes, dish placers, motor slot, etc., and take care of the assembly.
Grace, Pete, and Ben have been trying to debug the output speed issues with the current Arduino motor configuration. This project utilizes Arduino Uno with a motor shield as well two 512 step bipolar motors (5V and 12V) as well as a 200 step (12V) and an external power source. The 200 step motor is slightly larger than the other two and has higher torque. This motor was purchased after the fact as the group wasn’t sure if the former motors would have enough power to correctly move the mechanism.
Issues came about because the motor would output weak force that could be manually stopped fairly easily. Also it took around 3.5 seconds to perform one full rotation. The motors also only rotated in one direction when we expected them to be able turn back and forth.
Through some debugging, the group realized that there was a wiring issue which resolved the rotation issues as well increased the power output. Professor Costa also indicated that a stronger external power source (which the group purchased) would increase the output.
Mitchell, Kevin, and Pete calculated the exact angles the motor has to turn to (45 degrees). Accordingly, the motor will turn 64 steps (512 step motor) in each direction to achieve this.
As of now, the program is complete and will perform said actions upon a user initiated keystroke.