Bladders

The bladders were printed using TPE and was printed on a Snapmaker 250T. The reason why it was 3d printed is so that customs bladders could be created with ease and affordability in mind. For the bladder, it must meet each one of these criteria: be 3d printed, airtight, withstand high pressure, and as a minimium total height deformation of 6.5mm.

In order for the bladders to create the volumetric changes, they must be airtight. To achieve airtightness, 3 different processes were attempted: coating, using different 3d printers, and chemical smoothing. 

For coating, the first attempt was coating the 3d printed bladders with silicone. This however was a failure due to a chemical reaction between TPE and silicone which prevented the silicone from curing. After this, spray paint was used to see if it would produce the desired results. Even though spray painting was able to reduce the leaks in the bladders, the coating was too inconstant to produce a true airtight coating. 

The next method, using other printers, was also a failure. The theory behind this was that if a higher quality printer was used it would produce a print that was airtight. The reason why this was a failure was because the print quality was worse compared to the original. The only printer that able to produce a print the bladders at a higher quality was the POLYJET Printer. Even though the print was airtight, the material was too brittle and would not be useful for the project.

The final process was a chemical smoothing process. The first chemical that was used was chloroform. Chloroform was too aggressive and would eat through the bladders and cause the surface to blister. After this, DMSO, dimethyl sulfoxide, was used and it was able to produce a bladder that was completely airtight.