I initially had no ideas of what to print so I went to different websites and tried different prompts to pull up different objects. On maker world I found the impossible passthrough cone. It immediately appealed to me as the video made it look like a very fun fidget toy.
I went over to the bambu printers, downloaded the stl file, and scaled down the print by 5% to fit inside the capsule. I used PLA as that was the recommended filament for the file. The very first print was successful, so I printed three more. There was slight discrepancy between the ease of the pass through of the internal cone with some of the prints but after playing with it for 5 minutes it would loosen up.
I then moved on to the resin print. Upon setting up my print, I was skeptical because of the way the supports were being generated. The supports were everywhere including on the inside which had the potential to create issues. My first print came out feeling tacky and sticky even after 3 curing cycles and 4 hours in the sun. It also did not have the same transparency as other resin prints.
My second print had similar results and did not have the same transparency as other resin prints. Regardless, I kept going with removing the supports. This was a long and time-consuming process. The removal of the supports left a lot of marks and bumps on my pieces. As a result, the internal cone could not pass through. It would require a lot of sanding in spaces that are very difficult to reach to get the design to work.
Thankfully, a few students wanted to try the sls printer in which I was able to get my print added. The sls has high precision and accuracy but most importantly doesn’t need supports since the loose powder fills this role. After the parts came out, I spent an hour cleaning and loosening my parts.
Powder was lodged in the spirals, so I had to get it all out for the piece to work. Once the powder was removed, it was a very tight fit for the spirals to pass through. I had obviously not gotten all the powder out. I was initially concerned that my files were scaled wrong, so I grabbed my PLA part to compare. At that point, I decided to pass the nylon version through the PLA to test the sizing. It was much easier to pass the PLA and nylon than nylon-nylon. I used this to get out any remaining powder and to start loosening the nylon parts.
It was really cool to the see the nylon and PLA versions be interchangeable. Once the pieces got looser, I then tried nylon with nylon. It was very tight fitting but after playing with it for some time, it became much looser. It is still not as smooth as the PLA version but with time it can be. I think if the file was designed to be printed using SLS and nylon 11 it would come out much smoother. It was really cool to get to use the sls printer and compare it to the fdm print. The resin printer’s biggest drawback was the support generation. Since it put supports everywhere, it interfered with the design. The resin print is not suited for parts with movement.
Cost Breakdown
The cost of the resin print will be ignored as it is not part of my final design.
The sls printer and bambu printers are free with OEDK access. This significantly brings down the cost. Bambu labs provides a cost estimate for the print. Each print costs $0.50. About 20 minutes of labor is required to prepare the print, ensure it properly starts and removing from the printer. Charging a labor fee of $20/hr, the labor is about $7. Splitting the labor among the four parts results in each PLA impossible passthrough cone costing $2.25. This can be cheaper printing in larger quantities.
The sls print required two hours of labor and the material is a lot more expensive that PLA. The powder is expensive but printing in bulk would reduce the cost. Assuming that $10 of powder was used, the nylon version would cost:
- $40 in labor
- $10 for powder
For a total of $50.
