Photo of pumpkin print shows quality issue resulting from violating the 45 degree rule when using an FDM style printer. The bottom of the pumpkin has surfaces that are more than 45 degrees from vertical. These sloping surfaces have insufficient support when printing and can lead to drooping and uneven/rough surfaces. This is a common problem when trying to print spheres. Notice the surface of the top of the pumpkin is much smoother than the bottom section.
One solution to this problem is to slice the model into two part and print them with the flat side down. The model can then be glued together. The example shows that both halves of the pumpkin now have the same surface texture. Unfortunately, the seam between the halves is almost always visible and requires post processing to fix.
@Normand_Chamberland yes, he’s referring to the angle measured from the vertical axis. This is also a setting in most slicers for when to turn support on, so it’s a bit of a convention
Fwiw, I’ve found in PLA that having a fan blowing on the print improves overhangs night and day
@Eric_Moy Thanks, I’m familiar with this setting, it’s just that never having played with it, I was under the impression the angle was measured from the horizontal rather than the vertical axis. In any case it would make more sense to me…
Overhang issues are a weakness of FDM style 3D printers. The critical overhang angle will vary depending on the machine but the 45 degree from vertical is inside the safe zone. If you are designing for yourself, you can operate within the known limits of your printer.
If you are designing for others and the design starts to have overhangs larger than 45 degrees, you may want to consider adjusting the design or orientation on the build platform to avoid printing issues demonstrated in the photo. As the audience for 3D printing designs grows, we need to consider not only state of the art machines but also low end printers. A lot of work goes into creating a robust design that will be printable on a wide range of machines.
@John_Ridley Thanks for the tip re: hollowing model for gluing.
