Being able to use the 3D printer independently is the most anticipated part of this prototyping class. As a mechanical engineer who never had previous experience operating a 3D printer, working solely on making the 3D model in SolidWorks without going through the prototyping and fabricating process is never a complete learning experience. In this 3D printing assignment, I realized the time-consuming nature of prototyping and iterations needed to make adjustments to the mechanical design of the model. Going through the whole prototyping process, starting from making the 3D model to multiple iterations of prototype fabrications, definitely made me a better engineer.
How my cute lil owls were born
1. select my 3d shapefile from Thingiverse
This is the owl with egg shapefile I found from Thingiverse. I picked the STL file with the egg secured with a small post inside the see-through body. This cute owl with an egg inside its see-through belly is an “impossible object” with complex and internal geometry. It could practically be only manufactured with the use of 3D printing, as the see-through mesh in the owl’s belly and internal egg cannot be easily manufactured with traditional methods.
The owl with egg shapefile I picked from Thingiverse represents my school spirit. Go Owls
2. measure the gumball capsule size to determine the size of 3d print owl
I used the caliper in OEDK to measure the inner diameter of the gumball capsule. The inner diameter is in the range of 47-50 mm. I decided to make the size of my owl print on the safer side, having the largest side to be 40 mm. This way, I made sure the space inside the capsule was used to almost its maximum.
The inner diameter of the gumball capsule is measured to be around 47-50 mm.
3. import my owl STL file into slicer software
First, I imported the owl STL file into BambuStudio software to adjust the size parameters. I reduced the scale of the owl to 50% size to make the biggest side around 40 mm. I made sure the space inside the capsule was properly used to its maximum to fulfill the assignment requirements. No support was added after inspecting every layer before the print to minimize the overhang presented during the print.
The scale of the owl was reduced to 50% to make the biggest side around 40 mm, which is still a bit smaller than the capsule’s inner diameter of 50 mm.
4. start my FDM print in Bambu and prusa printer and failed rly fast
After adjusting the scale of the owl to 50%, I attempted my first print on both Bambu and Pursa printer using PC and PLA filament, respectively. As I was about to hype up the birth of my owl army, the first failed print happened really fast. The PLA print in the Prusa printer moved with the movement of the extrusion head due to poor adhesion to the build plate, which was caused by forgetting the use of a brim.
The first failed print in PLA on the Prusa printer moved with the extrusion head due to the lack of brim and poor adhesion to the print bed.
The outer brim only option was selected for better bed adhesion.
Perhaps the brittleness of the material in the PC caused the print in the Bambu printer to fail with a broken post underneath the egg, which was originally designed in the shapefile to hold the egg in place.
The PC print in the Bambu printer failed with a broken post underneath the egg to hold it in place.
This time, the flexibility in the PETG filament caused the print part in the Prusa printer to fail again with a dislocation of the egg. After several rounds of trial and error in two FDM printers, I came to a resolution that PLA is the better filament choice for my complicate internal geometry.
The PETG print failed to have the egg inside the owl.
5. back in the business of FDM 3d printing
Huge shout out to Ben at Rice NEI for training me on the use of both FDM and SLA printers. I get to have all three Prusa printers and one Bambu printer work all at the same time to increase productivity after dialing down the optimized parameters for my 3D print.
Thanks to the support from Ben at Rice NEI. I get the chance to work in my own comfort zone for my personal class project.
Both prints are from the Prusa printer. The owl on the left is PLA. The owl on the right is PETG, with the egg taken out during a pause of the print when the post for the egg failed again.
6. time to try the mighty sla printer
I imported the owl with egg STL file into the preferred slicer software, Lychee Slicer, for the Phrozen SLA resin printer. Next, I added the raft in the slicer software to ensure better adhesion to the build plate. I made the decision not to add support between the owl and the raft to minimize the number of print layers. I allowed the resin to settle for 10 minutes before starting the print to minimize bubble formation. Furthermore, I closely monitor the first few layers to ensure proper adhesion to the build plate.
Minutes later, with only around 20 layers built, the first two prints on the SLA printer failed on me again. As frustrated as I was, a coincidence happened while I was doing the second vat cleaning to remove the sunken resin print at the bottom. My hand hit the build plate when I was taking out the resin film from the vat. I realized that it was the looseness in the screw at the top to secure the build plate, causing poor adhesion between the raft and the plate.
Used the Vat Cleaning feature in the SLA printer to remove the failed print sunk to the bottom of the resin vat due to looseness in the screw to secure the build plate
However, not using the support to connect the part and the raft turned out to be a disaster in the end. Once the bottom of the owl was built and connected directly to the raft, it was a pain to even remove the raft without cracking the bottom of the owl. I allowed the resin print part to drain for around 10 minutes after the print due to Blu Lava Black’s higher viscosity. I used a metal scraper to remove the complete resin print from the build plate.
Finished SLA owl print on the build plate of Phrozen Sonic Mighty Revo using Siraya Tech Blu Lava 16K Professional UV Resin
Per Siraya Tech Blu Lava Black 16K Engineering UV Resin user manual, I placed all my resin print parts in the Form Wash for automated washing with tripropylene glycol monomethyl ether (TPM). I decided to use three times the recommended washing time by the resin supplier for a total of 30 minutes. The longer washing time was needed due to the complicate internal geometry of my owl.
My army of owls was cleaned in TPM solution using Form Wash for 30 minutes.
After cleaning with TPM solution for 30 minutes, I used compressed air to dry the part. Next, I inspected the surface of the resin print parts to make sure they were properly cleaned without feeling sticky on the surface. I followed the recommended UV wavelength range, 395-405 nm, by the resin supplier. The Form Cure I used was equipped with 405 nm UV light to complete the curing process of my owls. The curing took me around an hour to make sure the internal part of the owl was properly cured. Again, this took even longer than the resin supplier curing time at 15-20 minutes.
My baby owls are ready to be cured (baked) under 405 nm UV light in Form Cure.
I am content to witness the birth of my owl army after my resin print. The homogeneous surface finish of the resin SLA print has continued to impress me.
The mighty owl with an egg inside
7. clean up the workspace
I cleaned up the scraps on the FDM printer to make sure the next person after me could enjoy their journey and adventure in 3D printing. The workspace of the Resin SLA printer was cleaned using IPA (Isopropyl Alcohol) to remove residual resin on the metal scraper, rubber hammer, and build plate.
Cleaned up the workspace after the completion of my print
Reflection after completion
It took me almost a full weekend to familiarize myself with all the various aspects of both FDM and SLA printers. Now, I can confidently use both machines and make prototyping decisions based on the constraints and requirements of the design. The biggest lesson I learned throughout the prototyping process was that it is essential to spend time optimizing the design parameters and considerations. I cannot stress enough the importance of taking all the time you have to iterate in the design process. Thank you, and a huge shout-out to Ben at Rice Neuroengineering Initiative again for fully supporting my 3D printing endeavors to make me a better engineer in prototyping and fabrication.
Two main takeaways for future iterations and optimizations:
- Submerge the part in water during UV curing to increase efficiency, as I can still spot uncured resin at the bottom of the owl where it connects to the raft
- Add support between the raft and the bottom of the owl for the purpose of making five identical owl prints fit inside the gumball capsule
My zoo of owls, with some other impossible objects I printed when I was waiting for the resin SLA print to complete. The “articulate Taiwan” and “cube inside cube” from Thingiverse.
Manufacturing cost analysis
The overall cost of manufacturing my army of owls is $ 175.57, considering all materials, labor, overhead, and design. The cost of materials, including FDM printer filaments and the resin for the SLA printer, is surprisingly low, with a total of $ 8.57. With the understanding of the cost of other prototyping methods, 3D printing is definitely a good starting point for fast prototyping to achieve several iterations of design before moving into building larger-scale and more expensive models. We, as engineers aspiring to work in the medical device field, need to take advantage of the skills we honed in this class and push the boundaries faster to make the world better.
| Cost Type | Cost | Price | Source | Quantity | Total |
| Materials | Bambu Lab PC Filament (10 g/print) | $ 39.99 | us.store.bambulab.com | 1.5% roll | $ 0.6 |
| Bambu Lab PLA Basic Filament | $ 22.99 | us.store.bambulab.com | 4% roll | $ 0.92 | |
| Bambu Lab PETG Translucent Filament | $ 22.99 | us.store.bambulab.com | 1% roll | $ 0.23 | |
| Siraya Tech Blu Lava UV Resin (20 mL/print) | $ 49.99 | amazon.com | 13.64% bottle | $ 6.82 | |
| Labor | 3D Printing Operator | $ 22/hr | ZipRecruiter.com | 4 hr | $ 88 |
| Prototyping Engineer (You!) | $ 25/hr | Indeed.com (Engineering Intern) | 1 hr | $ 25 | |
| Overhead | Facility Cost (Machine Time) | $ 3/hr | jcadusa.com | 3 hr | $ 9 |
| Quality Control | $ 40/hr | ZipRecruiter.com (Quality Assurance Inspector) | 0.5 hr | $ 20 | |
| Design | Engineering and Development | $ 25/hr | Indeed.com (Engineering Intern) | 1 hr | $ 25 |
Total cost: $ 175.57
