Prototype
Currently, there are three functional prototypes that outline different functions of Hilo.
1. To-scale prototype
The to-scale prototype focuses on validating the roller, needle, and path movement of the device. This prototype is made up of two main components:
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The sewing mechanism that moves the needle through the pathway
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The conveyor belt system that translates the sewing mechanism laterally
After the first line of stitches is created, the second mechanism, the conveyor belt, is used to move the path over incrementally so the needle can then reverse its course to sew the next line.
1. Driving the needle through the pathway
2. Moving the needle-pathway incrementally
When prototyping this small model, we ran into manufacturing challenges that prevented us from creating stitches as the needle moves forward. We couldn’t manufacture a needle this complex and small ourselves so we decided to cut a stiff spring down to the size we needed. While this needle was able to move through the path successfully, it was difficult to sharpen the end adequately and it therefore struggled to puncture the fabric. Additionally, the spring’s size made it difficult to drill holes for the thread to even go through.
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To address these manufacturing constraints, we prototyped the stitching mechanism at a larger scale.
2. Stitching Mechanism
The stitching mechanism prototype allows us to demonstrate two additional functionalities of Hilo: stitching through fabric and pulling the thread through with the bobbin mechanism.
1. Driving the needle through the pathway
This prototype was successful in proving that a rubber roller can be used to drive the needle through fabric and create a line of stitches during each pass.
This prototype also shows that the needle can exit the fabric in preparation for the following line of stitches.
2. Bobbin pulls thread through two stitches
Although our original bobbin design would pull the thread through after a full line of stitches was completed, when we tried to prototype this mechanism we found that the bobbins could only reliably pull the length of thread in stitch increments of 2 or 3.
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Thus, we came up with a new design composed of two bobbin rods with 3 hooks each. The hooks are located incrementally along the pathway such that the entire length of thread will be pulled through every 3 stitches. After the needle passes a bobbin, the hook will catch the thread and begin to wind up the entire length of thread. Simultaneously, the previous bobbin will unwind, functioning like a full spool of thread. This new design remains to be prototyped.
3. Safety Mechanism
Hilo contains a number of complex moving parts, which could cause harm to users. The safety mechanism prototype exhibits the safety measures that ensure Hilo's secure functioning..
Hilo is in alignment with ISO 10821:2005 safety standards:
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Design prevents users from accessing danger zones while Hilo is turned on
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Limit switches cut the power to all motors immediately if the top of Hilo is removed
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LED lighting system tells users when Hilo is working, when when it's finished, when the top is open, and if Hilo encounters a fault leading the device to shut off.