Makefast Workshop, a Delaware-based design and manufacturing studio, posted a tutorial on their page detailing how to 3D print coils / springs in midair without support material. This is an amazing achievement.
3D printing unlocks geometries and shapes that cannot be achieved with other forms of manufacturing, but each type of 3D printer has its own limitations. For FDM (fused deposition molding) machines, one of the biggest limitations is overhang, or any angle greater than 45 °. Each part is 3D printed from bottom to top, with successive layers built on top of each other. Therefore, if the part has a steep inclination and depression on its underside, the part will need to be 3D printed by a pillar of support material below the overhang area. Supporting materials are costly and leave flaws when removed from parts, so most designers are trying to avoid overhangs by using chamfered chamfers and fillets in 3D printed models on FDM machines.
Makefast duo Maura Atwater and Adam Kumpf are degree problem solvers from Wellesley College and MIT, respectively, who solved the drape problem like anyone else: a little common sense and a lot of trial and error. They realize that the underlying problem of draping is hierarchy. Solution: Instead of extruding layers on top of each other, it extrudes directly onto the extruded stream itself.
Thermoplastics such as ABS and PLA for 3D printing have excellent glass-to-liquid transition properties, which means they can melt and solidify consistently and predictably when heated and cooled. By extruding the plastic very slowly, the print head is guided to move at the same rate; the fan on the print head cools the extrusion almost at the speed it came out, allowing it to solidify in place as a single stream. They wrote a command to generate the custom g-code that instructs TAZ 6 how to print without layers. "We made a short javascript function to draw the required 3D path, set the temperature, Feedrate, fan speed, etc. "
Obstacles need to be overcome, such as the moisture bag in the old filament popping up and interrupting subtle flow rates. Very consistent flow and motion is required, so vibration can also cause malfunctions. An interesting finding is that as parts get higher and higher, the extruder pull and thrust must be taken into account, which makes sense given the way the cantilever works. This means that the g-code of the cylindrical spring spreads out at the top to compensate for the inward drag of the extruder, as the height of the print becomes more and more apparent.
Nevertheless, springs are significantly stronger than other 3D printed springs, and these springs are affected by interlayer delamination when stressed. Their source code is freely available, as well as printing g-codes in multiple sizes and shapes on TAZ 6. Although it's a good thing to see the spring print as a single plastic stream, the more reward will be to see these control settings implement the slicing software. If the slicing software can include coding to extrude a circular pattern around the edges of the parts with overhangs very slowly, the use of support material will be unnecessary and the parts will be even stronger. The slicing program is always improving, so the slicing encoder will notice this.