Goliath Fall 2017

Post PDR Adjustments and 3D prints

Vanessa Enriquez (Manufacturing Engineer)
Approved By: Mark Huffman (Project Manager)


Vanessa Enriquez (Manufacturing Engineer)

After taking a closer look at the IR sensor, I realized that the sensor needed to be relocated to avoid contact with the first motor. The distance between the top panel and the front motor is not large enough to fit the sensor. Although we did consider redesigning the top, the tank will lose its overall ‘tank-like’ structure and the scaled dimensions would be skewed.

The top panel IR cut-out was relocated to the front of the bottom panel. The bottom panel was redesigned to fit the sensor between the first motor and the  3 dot board. I was able to create an IR sensor part to assemble along with the 3-dot board. The compact layout prevents the lengthening of the tank. Screw hinges were also added to the bottom panel to secure the side panels. Lastly, tank details were added to the side panels that were previously blank during PDR. The figure below shows the current layout for the components within the tank.

Figure 1 – Open Tank Assembly View

3D Printing

Vanessa Enriquez (Manufacturing Engineer)

The level 1 requirement states that the total print time will not exceed 6 hours with each individual part taking no more than 2 hours.

Figure 2 – MakerBot Layout

The files described here were printed by the Sojourner manufacturing engineer, Malak. She has access to 3D printers and offered to print the initial models. The figure below was set to print in ABS at the lowest quality. Unfortunately there were other issues with the printer that resulted in the model shown in figure 4. The total print time was 8+ hours. The prints seemed to have been cut-off at the same height across all components. This will have to be fixed before the second print. One option is to separate each side panel into two individual parts: the shell and the surface that connects to the bottom panel. This will mean that the final product will be glued together.

Figure 3 – First print goliath F17

The priority for the second print was to print functioning parts. Small adjustments were made and sent to print with Ridwan. After a couple of trial prints, the quality was set and printed in PLA. Although the F16 model was done in nGEN, only PLA was available at the time. Each side panel took over 2.36 hours to print.

Figure 4 – Second print goliath F17 assembly

After assembling the first model, I noticed some weak parts. The driving sprockets were coming apart when attached to the motors. Since this design was not altered since the successful F16 model, then I can conclude that by changing the material back to nGEN this issue will be resolved.

Figure 5 – PLA vs nGEN (respectively) for driving sprockets.

Other issues include misaligned cutouts for the io port and the IR sensor. The straps holding down the motors were too thin and broke off while cleaning the print.

I received the updated 3 dot dimensions from the other manufacturing engineers and adjusted the mounting on the bottom panel. In order to improve the side panel print time, I removed some of the designs that were added to resemble the actual 302 tank. The final design files have been sent to Ridwan (Nov. 29th). The final print time information will be updated when I receive the final parts.