Weird ripping and warping of ABS print I print my ABS at:


240 °C;
with a bedtemp of 80 °C; 
5 % rectilinear infill;
0.25 mm layer height;
2 solid layers top and bottom; 
Fan is completely disabled;
0.25 mm extrusion width;
50 mm/s perimeter print speed;
60 mm/s infill speed;
20 mm/s top solid and solid speed;
No acceleration.


When printing ABS, I place  an aluminum foil lined cardboard box over my printer to help keep the ambient temps up for less warping and stronger prints. I've never actually measured the temperature inside, but the cardboard box insulates very well. 

I get this weird kind of tearing in my prints, I'm not sure if it's from too large of gaps in my infill, too fast print speeds, or not enough top layers. 



Another guess is some kind of drooping because of the high ambient temps. 

The tearing only occurs on large top layer surfaces.
Looking at the infill pattern visible through the tears in the top layer, it looks as if you have unreliable extrusion on the infill layers also.

The solid fill layer is lifted and torn, so it is unlikely that one or two more layers of solid fill will make the result better.  In my experience, bumps lead to taller bumps and print failure.

These diagnostic steps have helped me:


Print a 3 layer solid fill version, the top surface should be smooth and free of bumps;
Print a single layer version, it should be smooth, well attached to the print bed, of even thickness, and a good surface for the next layer.


Given your results, I am suspicious that you may have one of these problems, which I've listed in the order of likelihood:


Partially blocked nozzle
Excessive drag from the filament supply, such as a spool with crossed filament which jams itself, preventing unwrapping;
Extruder feed roller slipping (perhaps full of dust), often a side effect of 1 and 2;
G-code error dropping the temperature;
Bad heater or thermistor, perhaps intermittent short of the thermistor, causing under heating even though the "average" indicated temperature is correct.


Printing gliders is a cool application. It shows off the weight advantage extrusion 3-D printing can deliver.  Nice.