Collection mechanism
Week 6 – Week 7 (16/6-27/6)
To read about how the collection mechanism works, please head over to the “Working Principle” tab.
- String has been attached to the plastic bottle and the closing mechanism works when string is stretched manually. Have not hooked it up to the motor yet
- collection mechanism has weak points which requires redesigning
Week 8 (30/6-4/7)
Breaking NEWS!!! (4/7)
It is a solemn day. Someone threw our 3D print into the trash. Detective Rauf is on the case, and he will report back. There is a current list of suspects, but this story is still developing (hence its appearance on the development page). Please stay tuned… Wish me luck.
Week 9 (7/7-11/7)
Assembling the sampling system is unexpectedly a pain in the behind. It was a challenge to superglue the hinge onto the container without getting the hinge mechanism stuck.
On top of that, although we’ve pretty much put the whole prototype together and the mechanism works according to plan, the lid is not closing tight enough onto the mouth of the container. To solve this, we tried playing around with magnets!
As usual, many iterations have been made to ensure that our prototype is in its best condition. Currently, we still have not reached a standard we are satisfied with, so we will continue to work on it in the following week!
Week 10 (14/7-18/7)
We started off the week with testing out our sampling bottle from an ambitious height of 10m. After a tense three minutes of lowering our sampling bottle from the winch manually, the first weight was released which unfortunately caused the bottle cap to close prematurely. The second weight was released subsequently, causing the crescent moon piece to break off. Bad news, all in all. We suspected that 1) the strings were too long and not taut enough, creating slack for the weight to accidentally come into contact with the rod, releasing the string holding the cap open 2) the weight was released from too high.
After some readjustment to our sampling bottle, we re-tested it at 5m height with one string inserted through the cap but nearer to the rod. The weight would only be released after the bottle has sunk into the ash. Unfortunately, at 5m height, the weight generated so much force that the bottle cap broke off entirely.
3D Prints
Sampling Bottle
Overview
Ring with Attached Crescent (RAC) and Crescent
In the beginning, we split this overall mount for the sampling container cap into 2 parts; the Ring with Attached Crescent (RAC) and crescent. This would allow us to insert the rod and spring into the crescent before mounting it onto the RAC. We wanted to superglue the crescent onto the RAC but it turned out not to mount securely together as it kept falling off and was not sticking. This can be observed in the picture with many fallen soldiers of super glue attempts.
Hence, we innovated and decided to attach the crescent to the RAC via a ‘puzzle piece’ approach. Rectangular fixtures were extended from the crescent and their corresponding slots were created in the RAC. The ring was also made taller so that there would be more room for the rod and spring to move vertically. Furthermore, we made the hole in the crescent of the RAC bigger to accomodate for the thicker rod.
A small hole was created on the crescent for one of the strings to be slotted through.
The small hole was then shifted to the other side of the large hole on the crescent. This helped to optimise the string position.
Progression of design
Container waistband
This attachment provides a slot for the string to be looped through and fixed on the other side of the container at its mid-range.
Rod
We attempted to recreate the structure of a Niskin sampler bottle by designing a hollow hooked structure in the rod. The ring that extends on the perimeter of the cylinder serves to support the spring.
Unfortunately the string would not stay in the compartment. Hence, design changes in the form of enlarging the hook had to be made
Our rod were extremely fragile and kept breaking so we decided to use the fillet function around the ring to reinforce the structure. The same was done to the hook so it would be easier for the string to be released when appropriate.
As we struggled with the string release mechanism, Guo Yao suggested that we make the hole solid instead so that the string can be more easily released. This turned out to be a great idea because it instantly solved our problem.
Lid
We initially wanted to mimic an actual container cap with walls surrounding the perimeter of the base. However, we realized that it would hinder the closing mechanism if not mounted in a fixed position about a pivot.
We then redesigned the cap with a hinge extension on the side for ease of mounting onto the container.
However, we realised that it would be difficult to mount that cap onto the sample container so we returned to the drawing board and decided to design a different type of cap. This cap, shaped like a very thin cylinder, would make the closing mechanism more efficient as there will be less room for error. Additionally, this design would also minimize the weight of the sampling system.
We made the cap even thinner so that we could minimize our weight even more. We were really pushing the limits with this one, but thankfully it was thick enough to withstand the pulling force of the string.
We created a hole in the middle of the cap for the string to go through, which is essential for the cap-closing mechanism.
We then decided to create a cap with 2 holes in order to optimise the string mechanism in the system.