NASA HEREC Core sample tool

Description: This is a simple design of a core sample retrieval tool for the instrumentation group on Purdue`s NASA HEREC 2022 Team designed by myself. The main goal of my process was to design a 3D printable tool capable of retrieving a minimum of 0.95 cubic inches of soil with ease. I have gone through two iterations so far that have been field-tested. I have stuck with the predecessor that is being shown throughout this report. I chose the second design because my first iteration could only withstand roughly 8lbs of force before having deformation while this one can withstand 9 times the amount. Moreover, some pros of my design are that with it being 3D printed it is extremely easy to replicate anywhere as long as a printer is available and it weighs a fraction of what similar metal tools weigh. In addition, the device can also be completely taken apart for easy storage! As for cons, the longevity of the device is most likely poor after excessive use, and the size is limited based on the printer available to the user. Overall, this is an inexpensive tool that shall prove useful in getting the team some extra points for the competition!

Figure 1: Shows some initial brainstorming and sketches of my design thinking for a solid sample retrieval tool.

Figure 2: Shows the assembly drawing for the instrument.

Figure 3: Shows the technical drawing for the handle.

Figure 4: Shows the technical drawing for the main core.

Figure 5: Shows the technical drawing for the plunger.

ORR :

• No changes have been made since the design review. Considerations of modifying the teeth of the core sample tooling have taken place.

• There has been an avoidance of sharp edges and corners of the design to ensure safety for the user. Note that those design considerations have hindered the mechanical advantage of the overall design when penetrating the soil.

• The design shown above has been 3D printed. All three parts were sliced using Ultimaker Cura and had a resolution of 0.12mm. The results of the real product are shown below in Figure 6

Figure 6 shows the manufactured product disassembled (left) and assembled (right).

• As long as the ground is soft there is no doubt in the functionality/performance of the tool. However, if the ground is tougher than expected, the faith in the functionality will dwindle.

• There is the potential for the tool to break and create sharp edges that could cause bodily harm. A way to mitigate this is by printing the parts at higher infill to reduce the potential of sharp edges from the points of fracture in addition to creating a stronger tool altogether.

• A list to verify mitigations

1. Assure the slicing software has the infill set to +60%

2. Created fillets at sharp corners and oriented the parts to print with the shear plane perpendicular to the force that will be applied.

List of procedures for use:

1. Assure that the main body, handle, and plunger are all present

2. If tooling is disassembled proceed with the following:

   1. With a firm grip on the main core, take the handle with the bowed side facing down and slide said handle in the horizontal through-hole located below the top platform.

   2. Ensure the hole through the handle is concentric with the center hole of the top platform.

   3. Take the plunger then slide and insert it from the top.

3. With the assembled core sample received tool in hand, apply a downward and torsion force with teeth facing down to the sample area. If additional force is required, use impact strength to shove the tool further down the soil. Make sure to hammer the tooling down with the plunger out and aim for the center of the platform.

4. Use the plunger to assess the amount of soil in the tool and when an adequate amount is retrieved, pull the core sample tool out of the soil and use the plunger to shove the sample out.