3D printing is a method for printing that produces three dimensional models out of plastic or other materials that can soften with heat. This page teaches about the most common method of 3D printing for small volume amateur and professional use and the machines that follow this method. This method is called Fused Filament Fabrication, FFF, and the machines are called 3D printers.
But why 3D print at all?
3D printing allows for quick construction of everything from household organizers to robot parts. It only requires one machine, so it can save time over traditional methods that require lots of up-front design and cost. Also, since it is an automated method of manufacture, the manufacturers do not need to be trained in all the skills that would traditionally be required, like mold making or machining. This last reason, combined with the vast online digital 3D model sharing communities, are likely the main reasons that 3D printing has caught on with amateurs.
Fused Filament Fabrication
FFF printing is a method for 3D printing that involves melting a filament through an extruder to build up a model layer-by-layer. There are other methods, but they are not as simple or cheap. These include stereolithography, powder bed fusion, computed axial lithography, and lamination.
To print something using FFF, first you must design a digital 3D model in software such as Fusion 360, Solidworks, Blender, or any number of other free or paid softwares. Alternatively, communities on the web share models for free, or to buy. This first step of the process is the same for any method. Then the models need to be processed through a system called slicing before being ready to print.
The central principal of FFF printing is control over a stream of melted material. The material starts as a spool, a little round wheel like the device that stores string, of filament. The filament is kept in a solid form until it is ready to be pressed out of the extruder onto the desired spot, very much like the process of using a hot glue gun. The extruder moves around, controlled by the motors of the 3D printer, to lay material onto a single layer. This continues until the final form is constructed by creating many thin layers on top of one another, see the below graphic.
Because the material is melted just enough so that it is soft, not runny, the material hardens almost immediately. This quick cooling has many benefits. One benefit is that the lower layers do not sag and droop, but they stay as they were printed. Another benefit is that small gaps can be printed over without very much sagging underneath, provided there is something for the material to hold onto on either end. Printing over small gaps is known by avid 3D printers as bridging, see the below graphic.
- Fused Filament Fabrication: A method for 3D printing that involves placing one layer of melted material on top of the next to build up a model.
- Digital 3D Model: A type of computer file that defines how a model should look in 3D. The models are made from points in space, lines attaching those points, and faces that fill up those lines, giving the model sides.
- Filament: A thin strand of material, often stored on spools, that will be melted and squeezed into place to build up the 3D model.
- Stereolithography: A method for 3D printing that involves slowly raising a plate out of a liquid plastic and using UV light to harden each layer from underneath.
- Powder Bed Fusion: A method for 3D printing that uses glue or lasers to fuse together particles in a bed of powder, then pours another thin layer of powder on top and repeats.
- Computed Axial Lithography: Like the above mentioned Stereolithography, this method hardens a model in the middle of a tank of liquid plastic too, but from the side instead.
- Lamination: A method for 3D printing whereby sheets of paper are cut into shapes, and then glued together in a stack to form the final model. The sheets can be colored by traditional laser printer methods.
- Fusion 360: A 3D modeling and simulation software by Autodesk that’s free for students.
- Solidworks: Another 3D modeling software by Dassault Systèmes. It’s often used in industry.
- Blender: A free 3D modeling software by the Blender Foundation.
- Slicing: The method for taking a solid 3D model and converting it into layers and the instructions for how the printer will print the model.
- Bridging: The process for squeezing plastic over small gaps on a printed model.
A 3D printer is a manufacturing machine that adds material to construct models, rather than remove material. 3D printers come in many varieties and are sold by many companies. Since FFF printing was explained above, here we look at the styles of printers capable of FFF printing. The whole purpose of any FFF 3D printer is to move an extruder around an area to lay down the melted material.
There are two main styles of printers, linear, and delta.
Most 3D printers that you will encounter will use this general design. It moves the extruder along straight paths called axes. There are 3 axes, one for each dimension, height, width, and depth. However, these dimensions are more commonly referred to as X, Y, and Z. The drivers of the motion in all modern 3D printers are a type of electric motor called stepper motors. Stepper motors, unlike normal motors, move at small intervals instead of continuously. They turn in a similar way to how the second hand of a clock moves, one tick at a time. This allows for great precision, which in turn allows for production of highly detailed models.
The linear design is robust because of its simplicity of principal, this can make them great for beginners at 3D printing to understand.
Some printers are fitted with a heated printbed. This is because as the printed material cools, it shrinks. If it shrinks too much, it may become unstuck from the printbed causing the rest of the printing process to fail. By heating the bottom of the already printed model, it is more likely to stay stuck down, saving lots of time and frustration.
Although delta style 3D printers are less common, they have found their niche in the market. They work by suspending the extruder between 3 arms supported by rails. The axes are less defined as in the linear, because they take the teamwork of all the arms moving in unison to different heights on the rails to realize. Despite this difference, these two types of printers are mostly the same.
Where delta 3D printers have excelled is in the desktop printer market. Not only are they generally sold in affordable price ranges, but they are cheaper to make taller. Printer manufacturers take full advantage of that, making delta printers often taller, but narrower than their linear counterparts. This makes them well suited for tall or long models.
3D Printer Definitions
- Extruder: A device that melts and squeezes melted material out through a tiny hole to build each model layer.
- Linear: A style of 3D printer that moves along straight paths.
- Delta: A style of 3D printer that has its extruder suspended between 3 arms.
- Axes: Pronounced ak-seez. The different directions, or dimensions that a printer is capable of. Also could refer to the rails or bars supporting the printer’s motion themselves.
- Stepper Motors: A kind of electric motor that rotates in small steps to allow for precision control.
- Printbed: Sometimes known as “build plate.” This is the area where the model is printed. These are sometimes heated.
- Rails: Grooved bars that the ends of the delta printer arms slide along.
- Desktop Printer: A 3D printer designed for home use and that is presumably small enough to sit on one’s desk.
Printing Your First Model
Now that you know how 3D printing works, how does the whole process look from start to finish? Follow these steps and see!
- Find or design a model: After deciding on what you might want printed, you can either go to a model sharing website to see if someone else had the same awesome idea, or design it yourself if you’re up for the challenge. Additionally, if you find a model that you almost like, or need help with ideas, you can ask us and we will be happy to help make modifications or give advice.
- Prepare the model for printing: Once you are happy with the model you have chosen, now it is time to slice the model and decide on what material, color, and infill you want. The angle that you position your model on the printbed is also important, since the model will be strongest along the grain of the layers. Layers can help with this step too.
- Print: Lastly, you (or Layers) will load the file onto a 3D printer, clean the printbed with isopropyl alcohol, apply an adhesive if necessary, and press go! A few minutes to hours later the printer will finish and a new idea has been brought into the world, one layer at a time.
Now it’s time for you to start looking! Here are some websites where you can find models or inspiration: