Printing Convex Overhangs

[Roxy]

Any time you try to print out in space where there isn't already a foundation, you are going to run into this problem. The problem is you have new filament being extruded that is just barely able to attach to the previous layer. It is very hot and as it cools, it will shrink and start pulling on itself. This causes it to warp upwards. There is no good answer for this, but different people go with different solutions. Some use a fan as the material is being laid down to try to help with the shrinkage. Some change the amount and type of the infill for certain types of overhang. Others use different materials that are less impacted by shrinkage. Some use beefier support material. And others (like me) avoid it if at all possible.

If you bring up Open_SCAD and put this code in, and compile and render you will get the attached .STL file. Probably, you can't print this without curling of the edges.

As you change the value for z=??; you will eventually be able to print with no issues at all. Right now I have z set at 83. My guess is if you set z=75; you will be able to just barely print the sphere. Hopefully, this will help you understand the problem!

z=83; difference() {
sphere(r=25);
translate([-20,-25,-z]) cube([60,60,60]);
}

Incidentally, this is not a 'convex overhang'. This is the exact opposite. But it was an easy way to show you the problem. We can do a similar little piece of code to help you see the limits of your printer doing 'Convex overhangs'.