Pill Cutter - Progress Blog 7: 3/26/2022

Hello and welcome back to our team's third blog post of 2022! We are the University of Houston's Mechanical Engineering Capstone Team 35: Progress Blog 7.

First off, we would like to talk about the work our team has conducted from March 12th through March 26th, 2022. Thus far, our team has fabricated all the components and assembled the device. And now, we are preparing to complete the device validation between March 28th and April 1st.

After the first 3D print of the multi-shapes disk was made, we determined that the disk needed to be redesigned to improve its functionality. Because of irregularities in the 3D printing process, the octagon-shaped holes looked very similar to the already-present circular holes. For that reason, we have changed the octagon shape to a significantly more common pill shape: the oval shape. In addition, we modified the disk by increasing the depth of each hole to ensure that pills properly fit in place. The disk’s design changes are shown below in Figures 1 and 2.

Figure 1: New shape in multi-shape disk (Updated disk is on the right).

Figure 2: Increased depth and reduced range of sizes (Updated disk is on the right)

Following the opportunity to meet with Mr. Stear from the HCC Fraga Campus, the team was granted access to the Fraga Makerspace program along with the 3D printers. This is where we decided to print the last portion of our device as well to implement the edits of the aforementioned piece. The recently 3D printed parts are is shown below in Figure 3.

Figure 3: 3D printed parts from HCC.

Some challenges the team came across include the inability to determine the hardness of the pills and obtaining all the pills necessary to validate the device. With the help of Dr. Hammami's teaching assistant, we attempted to determine the level of hardness of our pill samples using a Rockwell hardness tester. During the initial hardness test, the TA suggested the usage of the Rockwell Hardness C and F tip; we concluded that the test is inconclusive since the Rockwell hardness tester would crush the pills before any conclusive value could be acquired from the machine. After further consultation with Dr. Hammami, she suggested that we may have used an incorrect penetrator tip. Shown below in Table I are the possible penetrating tips to choose from. Given the circumstances of the test, the ideal tip would use the lowest major load (60 kg). Following Dr. Hammami’s advice, we plan to meet again with the TA to reevaluate the hardness tests with the recommended A and H penetrator tips.

Table I: Standard Rockwell Hardness Scale

The other challenge the team has encountered is the inability to obtain all the pills with specific shapes and sizes necessary for validation. Since many require a doctor's prescription to purchase, the only pills that the team can reasonably obtain are those sold over the counter. As for over-the-counter drugs, the most common shapes are either oval, oblong, or circular. Shown down below in Figure 4 is an image of the current pills that have been acquired for testing. It is clear that they also represent the aforementioned most common shapes.

Figure 4: Current pills acquired

As for the working period between March 27th and April 9th, we will begin working on the validation for the device as well as hold a meeting with the TA to reevaluate the hardness test.