When: 18 June 2019, 1pm to 7.30pm
Members present: All
We decided to settle our hardware first before figuring out the software (to Tony’s admonishment)! So this session was mainly spent discussing and designing the hardware we needed to get the project working.
Needle + Tubing “Connector”
Next, we began figuring out how we would like to connect the tubing (that would be connected to the Linear Actuator) to the needle. In other words, how to transfer the linear movement of the LA to the needle. We decided on a “connector” to accomplish this. It would be 3D-printed in 2 halves, that are finally screwed together to keep the tubing and needle securely in place. The movement of the LA will cause this “connector” piece to also move, and thus, the connecting needle as well, to produce the desired jabbing motion.
Sketch of the Needle-Tubing “Connector”
The first prototype for the “connector”
Our third prototype, with needle and tubing in place, and screwed in; observe how the ends are forced slightly apart
Unfortunately, the first prototype was not able to fit the needle well. The horizontal “hook” was not long enough. The holes left for the screws were way too small. Furthermore, for each half, we had forgotten to orientate the needle in the right direction: they should be mirror images of each other instead of direct copies.
Our second prototype didn’t fare as well. Even after extending the horizontal “hook”, it was still not long enough. And we realised that the cavity we chose for the tubing was not deep enough, so the wire would keep the two halves separated by quite a margin. The holes for the screws were still too small.
Our third prototype was much better; This time, the two halves could be completely screwed shut with the needle and tubing in place! The only criticism was that the long ends of the piece were slightly ajar due to the tubing and needle. To remedy this, we decided to edit our model further: we would have four (or six!) screws at the corners of the piece as well. We decided to print this tomorrow, during the progress update meeting.
The Main Body
Since we removed the extruder motor from our 3D Printer yesterday, we could freely design a new body to suit our needs for this project.
We needed a body that would allow the “connector” piece described above to rapidly move up and down in place. So we decided on having a larger box, with a cavity in the middle. This cavity would have height = [height of “connector” piece] + [distance desired for needle to move]. By ‘encasing’ the “connector” piece, we would be able to limit its movement to just an up-down motion. Similar to the “connector” piece, it would be 3D-printed in two halves, which are then screwed together to encase the “connector” piece within. It also needed those ‘mickey mouse ears’ at the back to allow it to be secured onto the moving piece of the 3D printer.
Sketch of the main body
By the end of our session, Claudia had managed to successfully model out the above piece. The final consideration was adding inner grooves in the cavity to account for the movement of the screws on the “connector” piece as it moved up and down.
Needle + Yarn Feeder Mk II
Finally, we revisted the needle & yarn feeder we had already 3D-printed in Update [#10]. But of course, that was only a prototype. The main edits we planned to make would be to change the base to be rectangular rather than circular, and to include a backing to it. This would allow it to be easily screwed onto the back of the main body described in the above section.
Sketch of Needle + Yarn Feeder Mk II
We haven’t managed to model this yet, but it should be relatively simple since we’ve already modeled a similar piece in the past.
Overall Progress
With each meeting, our project is getting increasingly clear and solid. Our plan to build an MVP by end-June doesn’t seem so far-fetched after all! We prepared the below rough project design for our Progress Update Meeting #2. It was prepared over the weekend, before today’s more fleshed-out designs were conceptualised, so it’s slightly outdated. But the main idea is still there.
Rough project design
Once we pin down the main body and its related components, the next step would be to confirm how the LA would be secured in our product. And when that’s settled, we can then move on to using code to control precise movements of the needle and printing movement.