My team members (Xinyin, Antonija, and Katherine) and I had to re-create a LUCIA pelvic frame for this final project. We modified the original design, with the most significant change being the holder of the cervix models. The rest of the model remained consistent with the original model.
Making the wooden frame
- Measured the dimensions of each board in the original model and recorded them.
- Using Adobe Illustrator to create laser-cutting AI files.
- We used EPILOG FUSION M2 for our laser cutting. When we first started cutting, we spent a lot of time trying different speeds to reduce the flames and burns of the wood during laser cutting. Finally, we decided to use speed 13 and cut five times to cut our board.
- Our first piece of wood was cut smoothly, and we got the desired shape.
- However, our second piece of wood did not cut the way we expected, probably because the wood had changed and was not flat like our first piece. Also, we forgot to change the speed setting when we cut the second wood.
- We used an orbital sander to grind the board down a little thinner to remove the cut pieces. However, we accidentally broke off a piece of needed material and laser cut the missing piece again.
- Since the wood used for the bottom of the original model was thicker, we used laser cutting to cut three identical pieces of bottom wood so that they could be glued together later. This allows thickness to be achieved while maintaining stability.
Making L Bracket Corner Braces
Since we didn’t have metal L-bracket corner braces in OEDK, we decided to 3D print them. By doing this, we can save the shipping time. Below are the steps I followed to create the L-bracket corner braces:
- Measured the original size of the metal angle bracket and the diameter (4mm) of the screws.
- Used TinkerCAD to create the STL file for 3D printing.
- I set the layer height to 0.15mm on Bambu and tried to print one.
- The holes (4mm) in my first version were too tight for the screws to fit through. So I adjusted the holes to 5mm.
- After the second attempt, the finished product can be screwed through well.
- Copied the same design seven times and printed the required amount at a time, and our corner braces were ready.
Making a cervical model holder & support
- At first, we wanted to copy the original model and use TinkerCAD to create the 3D printing file, but we found that we were missing some parts required by the original model, such as elastic bands, so we gave up this idea. The following pictures show the original model and the semi-finished product we drew on TinkerCAD.
- We looked online for an adjustable holder that others had made and modified. After we 3D printed it, we found that it could fix our cervix model well.
- However, there was no place for this holder to be fixed on the frame, so we decided to design another set of supports to fix it in one position. We used TinkerCAD to design our support structures and 3D printed them.
Post-processing
- We used sandpaper to smooth our wood surface.
- We used wood glue to stick the bottom parts of the model, and let them dry for 24 hours.
- Since we only clamped on one side of the wood when gluing, the other side warped up the next day. We glued and clamped the other side again with wood glue and let it dry for 24 hours. Finally, we got a good bottom wood.
- When we connected the two parts of the bottom with L-shape braces and screws, we felt that the structure was not stable enough, so we also used wood glue to glue the two parts together. Although the convenience of transportation is sacrificed, the stability of the overall structure is enhanced.
- Used screws to assemble all the parts. This step could be completed in three minutes. It was very straightforward.
- We used super glue to stick the cervical model holder and supports, and then sandpaper was used for the final polishing.
OUR FINAL PRODUCT:
Things that could be improved:
- The flexibility and stability of the 3D-printed L-shaped corner braces are still worse than those of the original metal ones. If we want to mass produce in the future, purchasing metal corner braces directly may be a more appropriate choice, which can save time and maintain stability.
- We use super glue for the cervical model holder supports to stick them to our model, which will cause transportation, assembly, and disassembly difficulties. We should be able to add items like Velcro to make this structure more flexible.
Cost analysis
Cost Type | Cost | Price | Source | Quantity | Total |
Materials | PLA filament | $19.99 / kg | Bambu Lab | 19.82g | $0.3962 |
Screws | $6.89 / 200 pieces | Hillsflatlumber.com | 44 pieces | $1.5158 | |
Wood board | $1.33/ piece | Amazon.com | 3 pieces | $3.99 | |
Wood glue | $0.8675 / oz | Walmart.com | 1 oz | $0.8675 | |
Superglue | $0.37/ count | Amazon.com | 1 count | $0.37 | |
Labor | Prototyping Engineer (Intern) | $17 / hour | ZipRecruiter.com | 10 hours | $170 |
Overhead | Bambu 3D printer (rental price) | $19 / day | Fatllama.com | 3 hours | $2.375 |
Laser cutter (rental price) | $10 / hour | University of Irvine | 2.5 hours | $25 | |
Sanding paper | $ 0.007 / cm2 | The Home Depot | 160 cm2 | $1.12 | |
Orbital Sander | $ 13 / 4 hrs | Home Depot.com | 20 minutes | $1.08 | |
Quality control | $27.5 / hour | LinkedIn.com | 0.5 hr | $13.75 | |
Design | Engineering and Development | $17 / hour | ZipRecruiter.com | 4 hours | $68 |
Misc. | Waste and Scrap | $0.17/L | Houstontx.gov | 0.2L | $0.034 |
Sum: $288.5
Clean table