Following the basics of printing, this will be a post about slicers. If you want to start 3D printing, one of the most crucial programs you will need is a slicer. The slicer determines how your printer will work to create your product. I’ll explain what a slicer does, which ones I use, and explain a few basic settings. I’ll also tell you where to find more info and community support to get your slicer printing just right.
What is a slicer?
A slicer is the name for the program that converts your 3D model (.STL format) into code that a 3D printer understands. It’s called a slicer because the 3D model is literally converted into slices of a certain thickness, these layers are then printed one at a time to create the product. Depending on which slicer you use, there are a lot of settings you can control, and I mean A LOT. Settings range from intuitive things like print speed to less obvious things like multiple extruders and materials. It can be very intimidating to start messing with these settings, but when you do it right it can mean the difference between a failed print or an excellent product. The settings vary per printer so this won’t be a list of the right settings, such a thing does not exist, unfortunately.
There are programs that integrate the slicer and 3D representation of your model into one neat user interface, one of these programs is Cura. Cura is the software created for the Ultimaker printers, and it is a nice and hassle-free program to get started with. Aside from the Ultimaker printers, there are some other printers that Cura has default settings for.
As far as selecting a slicer goes, most slicers have largely the same capabilities. You’ll want to start out with a slicer that you like, and when you run into a limitation, switch. My personal preference is Repetier, with Slic3r. Repetier is the user interface and communicates with my printer. It has a choice of 3rd party slicers and I personally like being able to switch slicers for different prints. As you can see below, the slicer slices the Benchy printer test into actual layers. Benchy is a popular printer test created by CreativeTools and downloaded from Thingiverse.
I will list a few basic settings here, I recommend not to mess with any other settings unless you encounter problems with your print and know what you’re doing. If you’d like to see more in-depth info on the more advanced settings, let me know in the comments. I will use the settings menu in Repetier with the CuraEngine because the layout is nice and clear. But don’t worry, these settings are present in all slicers.
Speed and quality
Speed and quality may seem very intuitive, speed goes down, quality goes up, right? Not really, quality in this sense means the layer resolution. Most printers can get away with a layer thickness down to 0.1mm. Be aware that a lower layer thickness means more passes and more print time. Decreasing the layer thickness too far may cause problems with your printer such as clogs.
Print speed, in the case of most printers, means the XY motion speed. This is the speed at which your print head can maximally travel over your product. This is always a max speed because speed varies during printing. There is a “slow” and “fast” column because you can select a print speed when slicing with a slider. These values are the limits of the slider.
This sets the maximum XY movement speed while the printer is extruding. This limits the movement speed while the material is coming out of the print head and your printer is building the model. This is the general speed of your print, with all the other speed below being tweaks to either speed up the process (infill speeds) or improve the surface finish (outer perimeter). When you are just starting out (and don’t have default settings for your printer), I recommend keeping anything but “travel” and “first layer” to the same values as “print”. Because of this, I will only explain “travel” and “first layer”.
This sets the maximum speed while the print head is moving from one place to another when the printhead is not extruding. This speed can be much greater than the print speed since there is no building taking place. This speed is often the maximum speed the printer can achieve.
The first layer in 3D printing is crucial because this is the layer that sticks to the build surface. If this fails to stick completely or partially, the print will fail or lift around corners. This speed is usually lower than the normal print speed.
Most slicers allow for different profiles, and in the picture, you can see I use only 2. These settings control the thickness of the individual layers, and the first layer separately. The first layer is the layer that determines how well the product sticks to the build surface. Because of this, it is usually squished down more than other layers. This can be done with a lower print speed, smaller layer thickness, and different extrusion speeds (volume). A good starting point is 0.2mm for layer height, 0.2mm for first layer height, and 100% for the extruder. If you encounter problems with first-layer adhesion (and your build surface is clean and prepped), I suggest playing around with the first layer settings.
The structures tab has a lot of data, but I will only explain the few settings that you’ll actually want to change right away. There are 4 main fields: infill, support, skirt and brim, raft. Each of these controls a different aspect of your print.
Every print consists of a wall and an infill. The wall is the part of the print that's solid and visible. The infill is the structure that's printed inside the walls. A hollow print would compress easily and break, the infill prevents this. The infill can have several shapes, in this example, it is set to “grid” which means that the infill will be squares printed horizontally. I prefer using “gyroid” whenever possible because this is an extremely strong 3D shape.
Support is the structure that is optional to print and is used to support overhangs in the print. If there is a part that would be printed in the air (think hanging branches on a tree), you’ll need support to create a surface in midair to print on. Support simply means that support structures are added, which you can break or cut away when the product is finished. The default settings are usually fine to start with, but if you are having trouble removing the support, change the pattern to “lines”.
Skirt and brim
The skirt or brim are structures used to improve adhesion on parts that have a very small bottom surface area (the bit that sticks to the bed). This creates a brim attached to the part to increase that surface area. I’ve never seen the need to use it, but there are situations in which it can’t be avoided. Default settings are fine to start with.
Similar to a brim/skirt, but instead of just creating more surface area, this actually raises the model off the build surface. Printing a raft for your print to sit on. Like the skirt/brim, I’ve never seen the need to use this. Default settings will work.
The extrusion tab is usually intimidating to new users. It has a lot of options, and not all of them are obvious from the name. By far the most important setting here is “nozzle diameter”. If this is off, you’ll never get a decent print.
Retraction is used when you have stringing or oozing in your print. Instead of just stopping the extruder when it’s not needed, it actually reverses it to retract the material. This prevents it from dripping out during travel movements. Retraction speed is how fast the reversing is, and distance is how far the filament is pulled back.
Z hop lifts the head slightly during travel movements, to prevent possible collisions with the printed product.
The nozzle diameter is the size of the hole that your material is deposited through. This diameter is usually stamped or engraved on the side of the nozzle, and it is important to set this value accordingly.
This is the setting for part cooling. Not all printers have a fan for part cooling (most do). This controls when in the print it switches on, and what the minimum head movement speed is.
This tab is the tab you’ll be playing with the most. Filament producers usually advise a printing temperature range, but this depends on a lot of factors. You’ll be playing with the print and bed temperature quite a bit to get the texture, adhesion, and finish right.
Filament diameter and flow
The filament diameter is the diameter of the filament (wire) that you buy on a spool. This is the source material of your product, and I recommend using a good quality filament. I’ve personally made the mistake of using cheap filament, and spent a lot of hours trying to troubleshoot it. Never was able to, and good filament solved all the issues I was having. Please do measure the thickness at several spots on the spool with a caliper, and input the actual thickness here. If you do that, 100% flow will likely be correct.
This is where science turns to magic. Getting the right temperature is often a case of empirical science, AKA trial, and error. The right print temperature depends on humidity, ambient temperature, and filament brand. When starting out, or buying from a new supplier, print a temperature tower to calibrate (make sure the temperature changes with each block). The right bed temperature is usually just above the glass transition temperature of your filament.
This controls your part cooling fan. The part cooling fan cools the extruded material to improve the tolerances throughout the print. I print mostly PLA, and for that, I want the fan on full whack. When printing other materials, lower settings can be preferable.
There you have it, the basics of slicer settings. Next up I’ll walk you through downloading your first model, converting it, and actually starting a print. If you are missing anything, found a mistake, or would like to see more in-depth info, reach out in the comments.