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Issues

Issues will now be listed in an unordered manner.

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With the dirt tested, the dirt had a tendency to stick to the inside of the shovel. Otherwise this scoop worked extremely well and reliably, very impressive. In the image below, if you squint you can see that dirt is stuck in the jaws of the shovel.

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Geneva Mechanism cam roller

The piece shown below has a setscrew in the side which is used to interface with a D-motor shaft. During testing this piece frequently popped off of the shaft. This is due to the set screw loosening in the plastic. A simple fix would be to switch this part to metal if this design were to be iterated. Another cause for concern would be why did the part pop in the first place? did the mechanism jam? it is difficult to differentiate these phenomena.

Test Tubes in Mechanism

This pertains only to the insertion of the test tubes into the mechanism. These were a pain in the ass to put into the mechanism. And once inserted, the tubes were extremely loose, as seen in the video below. An alternative to as what is shown in the first view videos at the top was to wrap tape around the test tubes and press them flush with the rotating carriage. This was sufficient for testing purposes. In future designs it will be important to ensure the test tubes are easy to insert into the mechanism.

Top Bearings

Bearings at the top of the mechanism were all loose, did not seem to impact performance, something worth noting.

Dirt into Test Tubes

This is potentially the biggest issue for the entire mechanism. Even when pulverized dry dirt is attempted to be put into the test tube by a pouring action, no dirt will enter the tiny hole in the plastic cap. This issue will need to be corrected for in the next design.