Cracking can be difficult to differentiate from temporary under extrusion but this section will help you figure it out and how to fix it.
Signs of cracking or layer separation:
On a first glance, it can be tricky to differentiate between cracking and temporary under-extrusion as both leave gaps in layers or leave the print looking like it’s missing layers. Best way to tell them apart is: cracked layers are clean cuts and might show a bit of an upwards bend or warp, while under-extrusion tends to leave a spongy material deposition in the cracks.
Explanation:
Cracking occurs when 3D printing layers separate because of the forces exerted on the print when layers cool at a different rate. Warping forces exceed the layer adhesion strength and the layers simply separate.
How to fix:
Lower layer height
You could be trying to print using a layer height that is too high for your nozzle. Maximum layer height should not exceed 75% of your nozzle size (i.e. 0.3mm for a 0.4mm nozzle).
Increase temperature
If you’re printing higher temperature materials (around 230°C or above), you may be printing too cold for that material. Increase your printing temperature in 5°C increment tests until the issue is resolved.
Reduce cooling
Slow down or turn off your part cooling fan speed. Avoid sudden large increases in fan speed like when going into bridging mode. We want to avoid drastic temperature changes.
Use an enclosure
Protect your print from drafts of cold air. If you’re not using a printer that is enclosed, build your own enclosure around it.
Round the edges
If after these changes, you’re still getting 3D print problems with layers separating it may be worth reducing the stress on the corners of the print by rounding the model, reducing the stress on the edges. You’ll notice sharp corners (like in the image above) will crack first as the stress here is greater.
Change filament
Some filaments simply have less layer adhesion than others. If you’ve tried all the tips above you may need to seek better quality filament that has solid 3D printing layer adhesion.
Filament specific tips:
ABS is highly susceptible to 3D printer layer separation due to cold air hitting the print before it has cooled down fully. We suggest no fans for rigid.ink ABS. rigid.ink ABS prints best in a fully enclosed and even heated chamber.
ASA can also be very susceptible to 3D printer layer separation. rigid.ink ASA does prefer a warm ambient temperature so a heated, closed chamber is best. However, it can be used with an unheated enclosure or even on an open printer with a simple draught shield (it’s the draughts that matter most!). This is why we suggest using minimal fans around 5-20% fan speed.
PLA may suffer from cracking and layer separation problems if you’re printing too cool. Try increasing the printing temperature in 5°C increments, until you get successful layer adhesion.