Week 14 – Fabrication Progress

This week was a very hectic week as all of us were heavily involved in the entire fabrication process due to the very limited amount of time left before the final technical review. As such, our progress accelerated very quickly.

At the same time, we had to think of the weight to trigger our container’s lever in case bicycle brakes didn’t work well. Ms Rubaina found a long, 500g weight, as pictured below. We were unable to test it out immediately as the container was not finalised yet, and also we had to drill a very long hole straight through the weight but did not have the equipment to do so.

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With regards to the acrylic electronics mount, as the piece was large and we already used 3 acrylic pieces from the Fab Lab, we had to use some recycled acrylic to cut it so as to not have to use another fresh piece just for the electronics. We also designed an electronics box to house all the electronics, complete with holes to mount the various boards on pillars.

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The original plan was to have our logo raster engraved onto the electronics boxes’ cover but due to a lack of time, we made away with it. Besides, it might have interfered with the GPS sensor’s operation since that area would not be 100% transparent. We used the laser cutter in the workshop, which has since been decommissioned, to cut out the pieces shown above.

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At the same time, we 3D printed many parts we needed such as L brackets, motor brackets, and more pipe brackets.

IMG_20160125_090257_HDRWe faced lots of trouble 3D printing the different parts because the printers kept failing, so we had to experiment around with different settings and had to keep trying to print the parts we needed. At the same time, we had to remain considerate so as to allow other groups to print parts they needed, or we shared the printers with other groups and tried to print as many pieces as we could on one platform.

We also tested out the water containers to verify that the new design was able to hold water well and keep it contained.

In the video you may see that water is dripping out from the front of the container despite it being sealed off. The reason for this is because the hole for the eye bolt was not waterproofed yet, but the container itself was able to hold water and keep it in properly.

Apart from that, we also tested out the amount of force needed to pull the container lever upwards. In the video below, you will see that it peaks out at about 3.1kg of force for it to snap open. This is not a problem for the servo motors as the servo motors have a stall torque of 6kg when 6V is supplied, as can be seen in its datasheet.

In conclusion, it has been a very fruitful week, and a very strong foundation has been set for us to continue from here on out.

Thomas Wong

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