Print Settings (FDM)

1. Layer Height

Think of layer height as the resolution of your print. This setting specifies the height of each individual layer of filament in your print.  Prints made with thinner layers will create more detailed prints with a smoother surface where it’s difficult to see each layer. The downside of thinner layers is that it takes more time to print something, since there will be more layers that make up your object; standard layers are 0.2mm tall, a higher resolution 0.1mm will at a minimum double your print times.

If you’re printing something without detail, a thicker layer might be a better option to get you a finished 3D print faster but its surface will be rougher and the individual layers will be more visible.  Low resolution printing is good for things like prototyping where details may not be necessary and where speed dominates. 

If you want to print something with intricate details, you will get the best print with a thinner layer height. Cura recommends settings of .05mm for a high resolution print like this Tudor Rose Box by Louise Driggers. There does become a point where a layer height that adequately captures all the details of your model will take days to 3D print even for a small model, and it’s at this point you may want to consider a resin 3D printer to handle your detailed project and use an FFF printer for your larger projects. If you do choose to print detailed with an FFF machine, 0.1mm is a reasonable lower limit for a 0.4mm nozzle.

2. Shell Thickness

Shells refers to the number of times the outer walls, or perimeters, of the design are traced by the 3D printer before starting the hollow inner sections of your design. This defines the thickness of the side walls and is one of the biggest factors in the strength of your print. Increasing this number will create thicker walls and improve the strength of the print. It is automatically set to .8, or 2 perimeters, so there shouldn’t be any reason to change this for decorative prints.  If you print something that will need more durability you may want to increase shell thickness up to 4 or 5 perimeters for tougher use cases.

3. Retraction

This feature tells the printer to pull the filament back from the nozzle and stop extruding filament when there are discontinuous surfaces in your print, like this one: (image here)

Retraction is almost always enabled, unless you are 3D printing with a flexible material that is less responsive to retractions. An improperly calibrated retraction can sometimes cause filament to jam; a retraction setting too high will pull molten plastic up into the cold side of the hotend where it solidifies and can’t be pushed back out. In this case, lowering the retraction distance can improve this.. If you find there is too much filament oozing out of the nozzle, leaving your print with a bunch of strings or clumps on the outer edges, then your retraction settings are too low and can be gradually increased.

4. Fill Density

Infill refers to the density of the space inside the outer shell of an object. You’ll notice this is measured in % instead of mm like the layer height.  If an object is printed with 100% infill, it will be completely solid. The higher the percentage of infill, the stronger and heavier the object will be and the more time and filament it will take to print. This can get expensive and time consuming if you’re printing with infill higher than necessary on every 3D print – so keep in mind what you’ll be using your print for. 

If you’re creating an item for display, 10-20% infill is recommended.  If you need something that is going to be more functional and sturdy, 40-50% infill is  more appropriate, and increasing perimeters at the same time will get more strength for less material. Slicer’s auto-generatednfill patterns create different grid-like patterns inside your object which gives the top layers of your model more support. 0%-5% infill can be valuable for fast prototypes that don’t need to be strong or look good and instead are just necessary to support later layers rather than provide any sort of strength.

One of our community members, Dan Steele is a fan of more infill than less:  

“For infill I have rarely found myself regretting adding to much, and have often been disappointed by adding to little.  For something with a large surface area on top I would generally use a minimum of 18% infill.  For something I wanted to be mechanically strong I would throw an extra shell in and go up to 40% infill.”