So you have heard about 3D printing but are not exactly clear on what it is or how it works. Maybe your kids have been asking that you buy a 3D printer for them because they have one at school or have used one at the local library or a neighbor’s house.
In this guide you through the basics of 3D printing to help you better understand the technology, what you can do with it and what you can’t do with it. I’ll even point you to some recommended 3D printers if you have made the decision to purchase one.
3D Printing is a generic term for Additive Manufacturing which is a class of manufacturing processes that build up objects on a layer-by-layer basis as opposed to the convention manufacturing process of machining which removes material to achieve the desired object. So, in general, when you hear someone talking about 3D printing they are referring to Additive Manufacturing.
For convenience, we will use the term 3D printing as it is more commonly recognized.
3D printing encompasses a number of different processes or modalities:
- Vat Photopolymerization – process where a vat of liquid photopolymer is cured using a laser or other form of radiation in a selective, layer-wise pattern
- Material Jetting – process where droplets of build material are ‘jetted’ onto the build surface in a pre-selected pattern
- Material Extrusion – process where material is dispensed or extruded through a nozzle in a pre-selected pattern
- Powder Bed Fusion – process where a powder material, usually a metal, is spread in a thin layer upon a build surface and selectively fused with a laser in a predetermined pattern
- Binder Jetting – process where a liquid bonding agent is selectively deposited to join metal powders in a predetermined pattern
- Sheet Lamination – process where pre-cut sheets of material are bonded together
- Direct Energy Deposition – process where material is melted as it is being deposited onto the build surface and fused to create the object
For the remainder of this post, we will be discussing the Material Extrusion 3D printing process. This specific 3D printing process is also known as Fused Deposition Modeling or Fused Filament Modeling and when you hear the term 3D printing people are generally talking about this process because it is the most common 3D printing process used by consumers – people like you and me.
Fused Filament Modeling – Basic Process
In Fused Filament Modeling (FFM), a line of polymer filament is pushed or pulled by an extruder mechanism to the print head where a heating element melts the polymer for subsequent extrusion through a nozzle onto the print surface in a predetermined pattern. The nozzle is mounted on a gantry system that moves with respect to the print surface in the pre-programmed pattern to print your object.
As the nozzle moves, a thin strand of hot filament is laid down onto the print surface to form a layer of the object being printed. Once the layer is complete, the print surface moves downward a specified distance and the nozzle starts laying down the next layer of material. In this way, the object is printed layer-by-layer until completed.
The melted filament extrudes out of the nozzle in a semi-liquid form to bond to the previously printed layer and quickly solidifies. To help the very first layer of melted filament adhere to the print surface, user often make the surface sticky with a glue stick or other material. Some filament materials are best printed onto a heated print surface to aid with adhesion.
When the object is completely printed it is easily removed from the print surface by hand or with the aid of a putty knife. Some clean-up may be required to remove what is called the raft on the bottom surface of the object as well as support structures.
The raft is a structure printed on to the build surface upon which the actual object is printed. Rafts have a surface area slightly larger than the boarder of the object and serve to not only give the object something to better adhere to but also to ‘stabilize’ the system before printing the actual object. Think of the raft as a few layers of sacrificial material.
Support structures are used to support portions of the object that would otherwise be hanging in mid-air. Remember that each layer of filament is either laid down onto the print surface or a previously printed layer of material. If the shape of the printed object requires that a new layer will extend too far beyond the edge of a previous layer, a support is required. The physics of 3D printing dictate that you simply cannot print onto thin air.
The general rule of thumb is that supports will be needed for any portion of the object that overhangs a previous portion by more than 45°. There are exceptions to the this rule but it is recommended to stay within these parameters to avoid what are called ‘failed prints’. The software that transforms your object from a 3D CAD model into the print pattern will automatically generate support structures where needed.
Filament comes in 1.75 mm and 3 mm diameters so you’ll need to know the size of your extruder before purchasing extra filament rolls. Most 3D printers come with 1 roll of filament so you won’t have to determine the diameter up front. The smaller 1.75 mm diameter is more common.
Filament is wound onto spools an is sized by weight. One kilogram spools are the most common weight size though you will see some filament manufacturers offering 0.5, 0.8 and 2kg spools as well.
There are 100’s of filament materials and colors available.
The most popular filament materials are PLA (polylactic acid), which is made from biodegradable materials, and ABS (acrylonitrile butadiene styrene), the same material that Lego (TM) blocks are made from.
You can purchase filaments in many types of materials including glow in the dark, flexible, conductive, carbon filled and metal filled among many others.
Different material types will impart different material properties into your printed objects. For example flexibility, toughness, impact resistance, chemical resistance, metal-like finish or electrical conductivity.
Click here to read my summary of a few different filament types available.
Click here to read my summary of various types of flexible filament.
As for available colors, there are literally hundreds of colors available. One company, ColorFabb, offers a custom filament coloring option if you have a need to print an object in a very specific color.
You can even print objects from multiple material types and/or colors. A dual extruder 3D printer will make dual material/dual color printer more straightforward.
Different filament materials require different printer settings such as extruder temperature, print surface temperature, extruder retraction settings, printing speeds and cooling fan speed. The best filament manufacturers test their filaments on a variety of 3D printers and offer optimum printer settings. PLA filament is the easiest to print with as it does not need a heated print surface. Other filaments, such as ABS, will require a heated print surface and flexible filaments work best with Direct Drive or Greg’s Wade extruder designs which are described below.
If you are really adventurous, desktop extruders are available to manufacture your own filament.
There are 3 configurations of 3D printers:
- Kits that require assembly
- Open designs
- Enclosed designs
It was not that long ago that essentially all 3D printers were kits. Early adopters of consumer 3D printers were, for the most part, tinkerers who loved to build things so printer manufacturers simply supplied all the components and the user put them together. This cut down on manufacturing and shipping costs. As more and more people got into 3D printing, manufacturers started to differentiate themselves over the competition so they started offering fully, or mostly, assembled printers.
As different filament materials became available, manufacturers started enclosing their printers to better manage the build chamber environment in terms of temperature and emissions. Enclosed printers also offer an extra element of safety to help prevent young fingers from touching hot components.
Entry level consumer 3D printers can be purchased for under $300 while higher end printers can cost upwards of $2000-$3000. There are a number of options are available for 3D printers over this wide price range but they all share essentially the same basic features:
- A structural frame
- A filament extruder mechanism
- A filament heating element or hot end
- Motors for moving the extruder mechanism relative to the printed object in the X, Y and Z axes
- A print surface
- A gantry system upon which the print surface and extruder mechanism move
- A user interface
The main components that make up 3D printers, such as stepper motors, limit switches, guide rods, bearings, pulley belts, nozzles and programmable logic controllers are relatively straightforward and common from a technical standpoint. So what sets one printer apart from the next and why the wide range in cost?
The answer is the same things that set a Lexus apart from a Toyota or a Cadillac apart from a Chevy – namely, quality of construction, ease of use and functionality. More expensive printers will be easier to use, have more options like multiple extruders and heated print surfaces and sturdier construction like metal support frames and machined gantry components.
Ease of use translates into more sophisticated operating software. Multiple extruders gives you more design freedom with your printed objects as you can run different colors and different materials through each extruder. Heated build surfaces allow you to print with a wider variety of filament materials. If your print surface is not heated, you are limited to printing only PLA filament which is fine for younger children or printing non-functional prototypes.
Before you go off and buy a 3D printer, you should think through who will be using the printer and what types of objects you want to print. In essence, can you live with a Chevy 3D printer, do you want all the bells and whistles of a Cadillac printer or something in between.
Another thing to consider is print volume which equates to the size of objects you can print. I advise to purchase a printer that provides the largest print volume, along with the other features you want, within your price range. As you get more proficient at printing, you will want to create bigger and bigger objects.
Click here for a review of the best 3D printers ranging in price from under $300 to over $1800.
The extruder is the mechanism that forces the filament into the print head’s heating element so the filament can be melted and extruded through the nozzle onto the print surface. During extrusion the filament is pushed against a toothed roller that ‘grabs’ onto the filament and moves it as the roller rotates.
There are 3 primary extruder designs: Direct, Greg’s Wade and Bowden.
Direct extruder designs are mounted directly onto the print head and, therefore, move with the print head as it follows the programmed printing path. This adds weight to the print head and can put extra strain on the motor or cause ‘overshoot’ when positioning the print head. This potential overshoot is normally not a problem for most consumer print jobs but could be a problem when trying to print objects with very fine details.
Greg’s Wade extruder designs are very similar to Direct extruder designs except that a larger gear mechanism is used. These types of extruders are most often found on printers designed for larger, 3 mm diameter filament.
Bowden extruders are mounted in a fixed location remote from the print head and, therefore, do not add to the inertia of the print head so a smaller motor can be used or printing speed can be increased with an equally sized motor. A downside of Bowden extruders is that they push the filament rather towards, rather than pulling the filament to the print head’s heating element. This can cause brittle filaments to break and flexible filaments to buckle and cause failed prints.
Most consumer 3D printers use Direct extruders.
The engineers at NinjaTek have created a video of the various types
When we talk about 3D printing software, there are two flavors. The first is design or modeling software that you use to create your 3D models for subsequent printing. The second is slicing software that converts your 3D models into code, a.k.a. g-code, that your printer understands and executes to print the object.
The good news is that you don’t even need modeling software. There is a huge number of already created 3D models that are available from websites such as Thingiverse. There are many free versions of modeling software available such as SketchUp. Of course, you can also purchase modeling software if you want to get into advanced modeling. The free versions do not have all the functionality of purchases versions.
Modeling software has a bit of a learning curve to become proficient at but as with anything, the more you use it, the better you become at it.
Practice makes perfect.
Some 3D printer manufacturers provide their own proprietary version of slicing software. Other manufacturers provide instructions to download open source versions of slicing software, such as Repetier Host, onto your computer. As with modeling software, you can also purchase slicing software, such as Simplify 3D.
Your 3D printer will come with instructions for setting up your slicing software and inputting the correct settings specific to your printer. Different filaments also require different printing setting which are selected in your slicing settings. The better filament suppliers will also provide optimum settings to achieve the best results with their specific filament. Here again, as you play around with the different slicer settings, you will, in time, dial in the settings that work best for your specific printer and filament combination.
So there you have it – a high level overview of the 3D printing process, printers, filament material and software. I hope this overview has helped you better understand how 3D printing works.
Some 3D printers, such as the FlashForge Finder or the Sindoh DP 200 come pretty much ready to print right out of the box. Others, like the Creality Ender 3 or the Bibo2 Touch require some assembly and software set up to get going.
While all 3D printers are pretty easy to use, you should expect a little trial and error as you experiment with different materials and larger, more complicated prints. Going through the trial and error process is actually part of the joy of 3D printing. There is a certain amount of satisfaction that comes with solving a problem and implementing the solution for creating successful prints.
That being said, whatever printer you choose, if you follow the manufacturer’s instructions, you will be printing your first component within minutes of getting your printer set up and operational. Printing a test component is actually the final step in the printer set up process.
So what will you be able to do with your new 3D printer?
Well, in addition to providing budding scientists with some really cool, real life, experience and exposure to technology, you will be able to print any number of trinkets and gadgets plus useful things like replacement brackets, C-clamps, cable routers, rubber tires for model cars/trucks and smart phone cases to name just a few.
Heck, there are even books out there that walk you through making money with your 3D printer.
In the end, the number of things you can print are only limited by your imagination.
What will you create?
If you have any questions or other insights about the 3D printing process, please leave them below in the comments section.