Proper settings in your 3D printing slicer program can mean the difference between a successful print and a failed print. That’s why it’s so important to know how “slicers” work and how each setting will affect your results.
We understand that the many settings in slicing software can be intimidating, especially for beginner makers. Sometimes even advanced makers can make mistakes and end up with failed prints. Just ask Pinshaper & experienced 3D printer, Zheng3! His picture below illustrates a simple but effective example of the difference that slice settings can have on a print.
Part of the problem is that the optimal slicer settings depend on what design you’re printing, what material you’re using, and the unique characteristics of your 3D printer so there is no “one profile fits all” that anyone can use on every 3D printer they encounter. The big question then is: how do you know what slice settings to adjust to match your requirements?
To break it down, let’s go through some of the basic features of a slicer, and talk about how each setting will affect your print. This is more of an introduction to the topic than an in-depth guide.
What Is a 3D Printer Slicing Program & What Does It Do?
A slicer is a 3D printing program that converts digital 3D models into instructions for your 3D printer to create an object. The slicer cuts your CAD model into horizontal layers based on the settings you choose, and calculates how much material your printer will need to extrude and how fast it does it. All of this information is then bundled up into a GCode file which is sent to your printer. Slicer settings directly impact the quality of your print so it’s important to have the right software and settings to get you the best quality print possible.
For these examples, we will use Cura (version 15.04.3), a free slicer with similar features to most other slicers.
The basic settings menu in an older version of Cura looks like this:
8 Slicer Settings You Need to Know & How They Work!
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.
For medium resolution designs, we recommend 0.2mm layers. Unless you’re printing something with lots of detail, this height should work perfectly for most designs with some level of detail like this Spiral Chess Set by BigBadBison.
Larger layers work best for prints that don’t have a lot of detail. We recommend 0.3mm layers for a “low resolution” print with little detail like this Elephant by le FabShop.
PRO TIP: 3D printing veteran Chris Halliday recommends changing one setting at a time, keeping track of how each incremental change affects your print!
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.
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:
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.”
To see the effects of different infill settings yourself, check out Eunny’s great Infill display for teaching.
5. Print Speed
Print speed refers to the speed at which the print head travels while it lays down filament. Optimal settings depend on what design you’re printing, the filament you’re using, the printer, and your layer height. Of course, everyone wants to print their object as quickly as possible, but fast print speeds can cause complications and messy looking prints.
In general, a slower speed will give you a higher quality print. A good starting point that every 3D printer should be able to handle is 30mm/s. You can play around with speed settings for each type of print move like perimeters, infill, external perimeters, etc. and see what works best for your setup. For most users, keeping the external perimeters at a lower speed will keep the print looking nice and raising the rest of the speeds can get the print job done quicker without affecting the look of the finished 3D print.
Supports are structures that help hold up 3D objects that don’t have enough base material to build off of as they are being printed. Since objects are printed in layers, parts of an object that extend past a certain angle will have nothing for the next layer of filament to build on. These are called overhangs and can create a drooping look without supports. For some 3D printers, anything more than 45 degrees is too much to print unsupported, for others they can stretch out to 70 degrees with ease.
How do you know whether or not your design needs supports?
- Anything in a “Y” shape is safe to print without support because it’s a gradual slope which still has enough material beneath it to keep it from drooping. This is another way to think of the 45 Degree Rule, which states that in general, overhangs with a slope greater than 45 degrees will require supports.
- Designs that take the form of an “H”, where the middle overhang connects to either side is called bridging. Some printers can handle this bridge with careful extrusion, but others may need supports to prevent drooping or a messy print.
- Anything with a “T” shaped overhang will need support to avoid drooping. As there is nothing at either end of the T to keep the shape upright.
In most slicers there are two types of support you can choose from:
Touching Build Plate – this is for designs where the section of the design that needs the support can attach to the build plate like this:
Everywhere – This is for more complex designs where there may be a layer of the design that overhangs in a place that won’t attach to a support coming from the build plate. The head on this design has an overhang but the supports won’t attach from the build plate to the head so it instead comes from his chest.
7. Platform Adhesion Type
These settings will affect how your model sticks to the print bed. When a 3D print doesn’t adhere well enough to the print bed, often it can warp and curl in a way that renders the part unusable. Sometimes it’s salvageable but often it’s scrap. If additional adhesive (properly matched for material compatibility) doesn’t improve adhesion, there are two main settings you can adjust to help:
Raft: A horizontal grid that goes under the object that acts as a platform to stick to the bed and build from (and it looks like a raft). They can also be useful when printing models with small parts at the bottom of your print, like animal feet. If you do choose to use a raft, it will leave rough edges on the bottom of your print when you remove it. These aren’t often used anymore, as there are other solutions that get to the root cause of the adhesion issues, like these bed adhesive options from our friends at MatterHackers.
Brim: Like a brim of a hat, brims are extra perimeters that extend past the border of your object which keep the bottom corners of your model down without leaving marks on the bottom of the object. This is a better option if your main objective is to get your model to stick to the print bed. Brims can also be used to stabilize delicate parts of an object that are isolated from the rest of the model like the legs of a table.
8. Initial layer thickness
This refers to the thickness of your very first layer on the print bed. If you want a more sturdy base for your print, you can make the initial layer thicker. Most slicers default to 0.3mm for 0.2mm normal layers, which gives a thick bottom layer that’s easy to build on and provides a little extra material to stick to the platform.
What’s the difference between initial layer thickness and bottom/top thickness in the basic settings? While the initial layer thickness is the very first layer that goes down, the bottom and top thickness refers to how many millimeters of solid material will be set down before your infill is created and how many millimeters of solid material will cap the infill at the top of the object (even the slopes).
These are the basic settings for a slicer program – if you want to get into more advanced territory, there are more settings but these are the main ones a beginner needs to be aware of.
PRO TIP: When venturing into more complicated prints, 3D printing pro Zheng3 has a few steps to add on to Chris Halliday’s advice on changing one setting at a time:
- Write down all your settings. Label these settings as a group with a capital letter. e.g. rex_A, rex_B, rex_C. Screenshots of print settings will be handy here.
- Write the letter on the finished print with a Sharpie so that you can reference the results when you’re studying a barrel full of mostly-identical test prints.
- Change one and only one slicing parameter and repeat from step 1 until you are satisfied with the print.
3 Different 3D Slicer Programs
If you haven’t figured out which slicer program works best with your printer, here’s some options on the market to get you started:
MatterControl is made by MatterHackers and has many useful features that anyone would appreciate having, like “software leveling” which would allow you to create your own mesh for your 3D printer even without an automatic bed leveler. With the built in Design Tools you can even create and share your own designs all within the slicer.
Download MatterControl for free here.
Cura is made by Ultimaker and is extremely user friendly & fast so it’s great for beginners. It is not a proprietary software so it works for multiple different printers. The tradeoff of the ease of use is that you have less control over some of the more detailed settings. There are, however lots of plugin options for you to add if you need any of those extra features.
Download Cura for free here.
This is an open source slicing project started by the RepRap Community & works on multiple printers. Their focus and design goal is ease of use and maintaining the original design. One unique feature is that it allows you to vary the infill pattern across layers which can increase the strength of your print. The user interface has improved dramatically since they just started and it has positive reviews from most of the community.
Download Slic3r for free here.
PRO TIP: Still need some advice on how to figure out slicers? Here’s a great overall tip from a 3D printing expert Richard Horne, compliments of 3D printing for beginners:
“Print out lots of 20mm cubes. It’s quite a boring object, but it can help ensure you have a well setup and calibrated machine.”
If you have another favourite slicer that you use, tell us about it! Anything we didn’t cover? Let us know and we can write about it in our next blog!