Editor's Note: This post is one of a series excerpted from Jason Griffey's Library Technology Report "3D Printers for Libraries."
I’m using the term operational software to refer to your direct interface with the 3D printer, whether you’re preparing STL files for printing or actually creating the output file that the printer understands. This post focuses on the software needed for Fused Deposition printing, as that’s the most likely to be of use in a library. And once you get into SLS and other types, the software/process will likely be proprietary.
Much like a desktop printer doesn’t speak “Microsoft Word,” even if that is the most common filetype that you print, 3D printers don’t actually print STL files. An STL is a mathematical representation of a shape, while the 3D printer itself needs instructions: how much filament to extrude, where and how fast to move the nozzle, how far and when to lower the build platform, how hot the extruder should be. The actual mechanical movements are encoded in a separate file, and the filetype depends on the printer. Most FDM printers use an open filetype, called a G-code file, that is an ascii representation of all of the values needed to create the object. G-code is handy; because it’s simply a text file, you can manually alter known values in order to change the way the print is done. If you want to lower the extrusion temperature, no need to re-encode the file. You can just change the value, once you know where it is. G-code is also open, which means there are multiple programs that can generate it.
The process of moving from STL file to G-code for 3D printing is called “slicing,” because you are in effect taking the 3D object and slicing it into thin layers that the printer will reproduce. Some slicing software has a ton of control, letting you “plate” the models. Plating means to place them on a virtual representation of the build plate of the printer, allowing for printing of muliple parts simultaneously by plating more than one STL. Other slicing software is more bare bones, allowing you to just make choices as to printer settings during the print process.
The most popular slicing engine is called, appropriately enough, Slic3r. Slic3r is an open source project that is usable as by itself, but is probably more commonly used as a backend slicing software for more popular packages that include plating and other options. These would include MatterControl, Pronterface, ReplicatorG and Repetier-Host, the most popular management software for 3D printers. Slic3r does allow for rough plating of objects, but its strength is in the detail given to the slicing process.
Slicr3r has three main areas of control: print settings, filament settings, and printer settings. Each can be saved independently of the other, allowing for a collection of presets to be designed around your most common printing needs. The simplest of these areas is the Printer setup, which allows you to set the size of the printer build platform, as well as details about the extruder. Generally speaking, you only need one printer setup for each printer that you want to use with Slic3r. The filament settings are also not likely to change much, as it only allows you to set the diameter of your filament and the desired printing temperature for the extruder and bed. The real power comes from the print settings, where you have almost total control over every other aspect of the behavior of the print. Under print settings, you’ll find options for layer height, infill, speed, skirt and brim, support, and more.
We’ve discussed layer height, but the other settings are likely to be a bit mysterious. Infill controls the solidity of the print, the amount of material used to fill the interior, expressed as a percentage. The software does the math and determines how to arrange the type of infill you choose (square, hexagonal, etc.) in order to achieve the correct percentage of infill. As an example, if we were printing a 200mm by 200mm cube, and wanted it to be totally hollow, we would set the infill to 0. Setting the infill to a very low percentage, between 1% and 10% or so would result in very large square or hexagonal infill on each later, and as you increased the percntage, the infill would become more and more dense, until at 100% infill you would get an actually solid piece of plastic. You would almost never print an object at that infill, as there is a dimishing return for increasing the infill as it relates to strength versus the amount of plastic used. More than 60-70% or so, you’ll likely not find any actual structural advantage unless there is a specific geometry that needs to be solid. I find myself printing most objects at less than a 20% infill, which is a sweet spot of strength and weight to amount of plastic (and thus cost to print).
Speed is the rate at which the print head moves around the build plate. FDM printing is a slow effort, and one way to speed the process is to make the print head move faster as it’s depositing the plastic. Simply cranking the speed up has issues though. As you increase the speed, you’ll reach a point at which you will begin to decrease the quality of the output. The speed for moving and cleanly extruding plastic has its limits, and each printer has a sweet spot of speed for producing great looking prints as quickly as possible. The other issue is the weight of the print heads on these printers, which is fairly heavy, with their motors and metal heat sinks and brass nozzles. As you begin to move this not-insubstantial mass faster and faster, you create a significant amount of inertia that can be more than the printer body can contain. Videos online show printers “walking” across a desk as the print head is thrown back and forth across the build plate.
The last part of the print settings that you want to pay particular attention to is the support material settings. This includes both raft settings as well as support settings. A raft is a thin (2-3 layer) platform of plastic that can be printed as a sort of buffer between the build plate and the print itself. For certain prints, this can help with adhesion and curl issues. Also important are supports, which are vertical structures built not as a part of the model but to support an overhang in the model, giving the printer a base layer upon which to print it. You can choose whether to use supports and their shape.
After you get all of these settings tuned for your particular printer, few changes are required from print to print. Slic3r supports saving profiles, so you could do a series of printer settings for the slight variations that you might do most often, like 10% infill, 25% infill, etc. Or if you print with multiple filament types, you could have one profile for PLA, and another for ABS, with all of the appropriate temperature changes and such preset.
Slic3r works with any 3D fused deposition printer that speaks G-code, which is the vast majority. The bad news is that the most popular 3D printer for libraries doesn’t use G-code, isn’t compatible with Slic3r, and instead uses proprietary software and slicing filetype. I’m talking, of course, about Makerbot and Makerware.
Makerbot is by far the most popular consumer 3D printer company on the market today. They’ve likely sold more FDM printers to consumers than all other printer manufacturers combined, and they have chosen to go their own way when it comes to software to run their printers. Makerbot printers made prior to this year use software called Makerware to manage their printing, and it’s a far more user-friendly process than I’ve described for Slic3r above. The newest Makerbot printers (their 5th generation printers) are designed to use even more powerful software, Makerbot Desktop. We’ll talk a little about both below, although Desktop was in beta at the time I prepared my Library Technology Report.
Makerware is an all-in-one Makerbot management tool. It will take one or more STL files, allow you to place them on the build platform, rotate, scale, and otherwise manipulate them, and then set all of your printer specifics before hitting print. It’s visual, easy to use, and designed for first-use 3D printing. If you have a Makerbot model with multiple extruders, it also allows you to set the specifics of each extruder, and designate which parts on the build platform get built in the respective plastics.
Makerware also has the ability to output a printable file that can be moved to the printer on an SD card, although Makerbot doesn’t use the standard G-code format that most other 3D printers use. Their proprietary file format (x3g) isn’t compatible with other printers. You can also print directly to a compatible Makerbot printer that is connected by USB. Most people with experience recommend printing from the SD card, rather than live from computer, because it eliminates possible problems like a reboot or a program crash.
Makerware is compatible with all of the Makerbot printers prior to the 5th generation (the Replicator, Replicator 2, Replicator 2x).
Makerbot Desktop is the newest 3D printer software for controlling Makerbot 5th generation printers. Those are the Replicator Mini, the Replicator (5th Gen), and the Replicator Z18. They require a different software, because they’ve added a lot of hardware features not found on other 3D printers, including built-in webcams, wifi accessibility, “smart” extruders, and more.
While the interface for Makerbot Desktop is slightly different, the basic functionality is the same as Makerware. You can import, position, rotate, and plate STL files to prep them for output. But that’s the least of its features, as it also includes access to the new Makerbot Cloud service, allowing you to maintain a library of 3D designs in the cloud, and access them from any computer running Makerbot Desktop simply by logging in. They have also introduced yet another filetype, the .makerbot file, which is used as the printable output file for the 5th generation printers.
The addition of cameras in each of the new Makerbot printers also enables Makerbot Desktop to be a visual monitor of your prints, regardless of where you are. You are able to view the printing locally or remotely, and control the printer remotely, including pausing or cancelling prints. You can even use it to snap pics for uploading of your model to Thingiverse.
For libraries, the biggest impact might be felt by use of one of the smallest actual feature additions to Makerbot Desktop. When you plate an STL file in Makerbot Desktop, it can give you both a time-to-print estimate and a total amount of plastic used, both of which are almost impossible to determine before you print on pretty much any other platform.
Editor's Note: This post is one of a series excerpted from Jason Griffey's Library Technology Report "3D Printers for Libraries."
In addition to creating “born digital” objects, you can digitize existing real-world objects to make them printable. Of the various methods of 3D scanning, as it's usually called, I’ll cover my favorite three possibilities at the moment. Like much of 3D printing, the technology for scanning is changing quickly.
Still a rough art, no capture method in 3D scanning reproduces exactly the object. Some types of scanning technology have issues with separating the background from object or even factors like going from a very dark to a very light surface. Most 3D scans will require some finessing in order to get good results from the resultant print. With a bit of work, though, you can get really interesting and useful objects from a scanner.
Makerbot Industries has released a desktop 3D scanner called the Digitizer. Roughly the size of a turntable, it scans objects up to 8 inches in diameter. It uses a camera and lasers to “draw” the edges of an object as it is slowly turned around a single point. The Digitizer is also linked to the Makerbot Desktop software. If you have a Makerbot printer, you can set up the Digitizer + Replicator to act like a copy machine, placing an object on the Digitizer platform and then feeding the file directly to the Replicator.
The Digitizer is limited in that it only collects volumetric information and can’t capture surface colors. Other scanners can, and while the most common FDM printers available now can’t do full color, higher end printers can. It may be a situation where scanning things and expecting them to be archival quality will become more realistic as the scanners get better. The Digitizer now sells for $799.
3D Systems Sense
Sense by 3D systems is a handheld scanner that uses proprietary methods (but include at least camera and IR sensors) to create 3D scans of objects from 8 inches to 118 inches. It’s a far more interesting and overall more powerful scanner than the Digitizer in that it allows you to scan absolutely arbitrary objects, rather than being limited to things that will fit onto a turntable. You can scan freestanding objects, people, parts of rooms, nearly anything.
The software for the system originally ran only on Windows PCs, but they recently released a version for Macintosh systems. They also showed off a version of the Sense that worked with the iPad at CES 2014, which would be an excellent truly portable solution.
Sense also has price going for it. It’s only $399 for the basic Sense unit, and for the power that it affords you, it’s a very good deal.
The last of the 3D scanning gadgets that I’ll cover actually isn’t a gadget at all. The 123D Catch is one of the coolest options for capturing a physical object. The software and app-based option uses standard photographs to recreate objects through the use of very clever and complicated math. You simply take a series of photos around the object, changing the position each time, until you circumscribe the object in roughly 15 degree arcs. The software then interpolates the object from the photos, using the shadows and highlights to get depth from the series of photos.
The 123D Catch is available in three forms: free as a universal iOS app that allows you to take pics in the app itself; as a Windows app that allows you to load photos into it directly from another source (a DSLR or other digital camera); or as a web app that does many of the same things as the PC app, allowing you to upload photos taken elsewhere and convert them to a 3D model.
All of these are free to use, in limited ways. The free version is licensed only for noncommercial uses of the models. It’s borderline magic, especially as a freely available service, what 123D Catch can do with static 2D photographs. The key advantage of this is that you can use it in places that would look at you oddly if you brought in a dedicated 3D scanner, but don’t blink if you take a series of photographs. Think about 123D Catch at next museum or art gallery you visit, and take a few extra shots and give it a try.
Editor's Note: This is the fifth of a series of posts excerpted from Jason Griffey's Library Technology Report "3D Printers for Libraries."
Let’s start with a high-level overview of the process FDM printers follow, which is similar regardless of printer. You start with a digital model of your object, in STL format, either created with one of the software packages described below or downloaded from a website. You open the file in a plating and slicing program, like Makerware, Repetier host, ReplicatorG, or Pronterface. The program will show how the object sits on the build platform, and you can manipulate it to some degree (scale it up or down, rotate it for a better fit). You will then choose a number of settings for slicing, things like layer height, infill, and extrusion temperature. Once you have your settings, you will either print directly from the computer over USB or export the STL file as a gcode file and move it to the printer on an SD card. The STL will be sliced into hundreds of layers, and the 3D printer will get instructions on how to build it one layer and a time.
The other half of the 3D printing process is the software, which is of two types: one prepares your designed files for printing (slicing and plating software); the other is design software for creating the 3D object that you wish to print. We'll cover design software here.
The two filetype standards for 3D printing are .stl and .obj. Obj files are typically those used in high-end printing, and include features like color information that are superfluous for the sorts of consumer-level printing that libraries are likely to offer. For FDM and STL printing, the needed output file is a .stl format. This is the equivalent of needing a .docx file if you want to work in the most recent version of word, or a .pdf file for cross-platform document consumption. The .stl file is a very simple description, in either ascii or binary, of the external shell of a 3D object in terms of triangles. Nearly every 3D modeling software that you might use will export to .stl, it is that common a file format in 3D design.
One of the things that has really helped the 3D printing business take off is the availability of freely-sharable .stl models of just about anything you can think up. The most popular online library of 3D models is Thingiverse, a freely available resource owned by Makerbot Industries. Thingiverse allows anyone who has created a 3D model to upload it to the website and make it available for download. It’s open access 3D objects, in effect. Thingiverse is the perfect first-stop for anyone who has a 3D printer, as it will give you hundreds of things to print, from toys to tools. The downloadable files have easy to follow instructions for printing as necessary and clearly labeled intellectual property rights.
As libraries start creating and sharing objects, Thingiverse would be the logical place to store them, especially for findability by the 3D community. I’m hopeful that over time we’ll be able to find shelf brackets and more there.
I’m going to sequence this recommendation area for 3D design software from beginner to expert levels. With far more options for design software than I can cover here, this section, divided by level of expertise, is designed to give you a solid starting point. I will also point out a couple of options for the creation of STL files from photographs.
My favorite piece of software for the beginning in 3D design is a website called Tinkercad. Tinkercad is a freely-available web application for creating of 3D models by using simple shapes to build up more complicated ones. You must create an account, but the free account (at least currently) gives you unlimited models online. The free account’s only real limitation is the requirement that your creations be Creative Commons Attribution-Share Alike 3.0 license. Paid accounts get the ability to choose among all of the available Creative Commons licenses as well as the ability to control commercial distribution of their models.
Tinkercad is entirely browser-based and runs on any modern web browser, so it’s trivial to run on nearly any computer. With a well-done introductory tutorial for beginners, its method of building with simple basic shapes (cube, sphere, pyramid) allows people who are new to 3D modelling to start slowly, but still gain understanding of basic concepts. It also clearly labels the size of objects for output and allows for either solids or holes of any arbitrary shape.
Tinkercad supports importing other STL files, which means that it’s possible to download an STL from Thingiverse, import it into Tinkercad, and modify it. Though you can’t customize as robustly as with full 3D modeling software, for first steps towards creativity in the 3D realm, Tinkercad is a fantastic tool.
Similar to Tinkercad and also browser based is 3DTin. I find it less intuitive than Tinkercad, but it has some tools (camera movement, for example) that might make it a useful answer for a problem you have in 3D creation.
A step up from Tinkercad is SketchUp, software that was formerly owned by Google but sold off in 2012 to Trimble Navigation. There are two version of SketchUp available, SketchUp Make and SketchUp Pro. SketchUp Make is freely available for noncommercial use and has every capability that I can imagine a library or patron needing. SketchUp Pro is designed for professional architects and others who need very professional level controls and output.
SketchUp is ostensibly designed for architectural renderings—building interiors and exteriors, landscape design, that sort of thing. Like Tinkercad, it deals in just a few basic shapes and controls and flexible in its design uses. As a bonus, the SketchUp website has dozens of learning resources that you can use to both learn and teach with.
SketchUp doesn’t natively export to STL for 3D printing, but with an easily installed plugin you can export or import any STL file. As Google Earth and Google Maps’ primary tool for creating buildings, Sketchup is particularly handy if that’s your interest. SketchUp. It maintains a 3D warehouse of buildings and objects that can be easily opened and printed, including pretty much every famous building or sculpture in the world. Want a copy of the Taj Mahal on your desk? Not problem with SketchUp and a 3D printer. Ditto for the Empire State Building, the Arc de Triumph, or the Tennessee Aquarium. All of those are available and already modeled for your use.
Another of the free tools is Blender. Blender is an open source 3D computer graphics program that is used not only for basic 3D model creation but full animation and movie making. Of the software that I’ve mentioned, if Tinkercad is a moped, and SketchUp is a motorcycle, then Blender is a Saturn 5 rocket. It is indescribably more complex than either of the other tools to such a degree that I would really only recommend it for people who have previous experience with professional-level 3D tools.
With that caveat, it is a fully professional level tool that is capable of creating completely realized 3D photorealistic models. And it’s free. This combination means that there’s little reason not to at least play with it, or have it available if a patron wants to use it. It is worth considering whether or not you will be able to offer assistance to your patrons using Blender, because for most libraries the answer would be no. I’m not saying that’s a bad thing, only that you should be aware of the complexity of the program.
The last of the free tools I suggest taking a look at is OpenSCAD, an open source CAD editor and also a professional tool. Whereas Blender’s strength is in the artistic and creative, OpenSCAD’s strength is in the mechanical and engineering aspects of 3D modeling. If you want to model a turbine impeller or a structural support, OpenSCAD is likely your tool. Much like Blender, however, it is definitively a professional tool, requiring serious research and effort to get into.
Most of the commercial tools for 3D model creation are tied heavily to specific professions. It’s likely that if your library needs them, you’ll already know it because of local demand. Academic libraries specifically may need to pay close attention to the areas they are serving. Classes that use AutoCAD are unlikely to also teach Maya software, but either may be important to your patrons.
Editor's Note: This is the fourth of a series of posts excerpted from Jason Griffey's Library Technology Report "3D Printers for Libraries."
As noted in earlier posts in the series, FDM (fused depostion modeling) printing is by far the most common inexpensive method of 3D printing. In this post, we’ll look at alternatives.
We are starting to see stereolithography (SLA) printing move downmarket into the affordable-for-libraries zone. I’m aware of a couple of libraries that have already purchased stereolithography printers.
SLA involves a light-sensitive resin and lasers. Liquid resin is contained in the body of the printer, with a build plate that moves up and down inside the resin. The resin solidifies when exposed to a specific wavelength of light, usually in the UV spectrum, and the printer has a laser or lasers tuned to that specific wavelength. The build plate starts near the top of the resin, and the lasers sweep across, solidifying the resin in the appropriate areas. The build plate then lowers, and the lasers repeat their sweep, building layer after layer, one after the other as the object is built. You can also have this process occur upside down, as in the FormLabs Form 1 printer, where the build plate is actually above the resin, and as layers are added it pulls the completed layer out of the resin.
SLA printing has several advantages over FDM. Because the print is always encased in liquid resin during the process, it is much more forgiving as to geometry of design. Not completely-- there still has to be some connection to the base layer. You couldn’t print a “floating” horizontal piece, for instance. But in general, the resin provides substantially more support for designs than those available from FDM printers. The other major advantage is that the detail level is limited by the crystallization of the liquid and the size of the lasers, which means that you can have very fine details in an SLA print. It’s possible to achieve .025mm (25 microns) layer heights with SLA prints.
Stereolithography printing has its limitations. The first is that the resin is only available in a very limited number of colors, generally a clear or translucent material and white. When compared to the rainbow of colors available for FDM printing with ABS or PLA, it feels limiting. The second, and far more worrisome, is that most vendors of this type of printer manufacture their own resin. The printers are designed to tune the wavelength of the lasers to the specific resin they sell, thus making it very difficult for anyone to compete with them on consumables for the printer. This would be the equivalent of buying a printer from HP, and having to then buy paper and toner from them as well in order to use the printer.
Small SLA printers are just beginning to hit the market, available in the $2,500-3,500 range. The consumable for printing, the photosensitive resin, is more expensive than filament for FDM printing as well. The most popular of consumer-grade SLA printers, the FormLabs Form 1, has resin that sells for $149 per liter.
Selective Laser Sintering
Simultaneously the most flexible and the most expensive type of 3D printing commonly used, selective laser sintering (SLS) printing is similar to stereolithography in that it uses lasers to solidify a loose substrate. In SLS printing, the printing substrate is a powder, and the printers use high-energy lasers, rather than UV. The high-energy lasers selectively fuse sections of a powder together, a new layer of powder is deposited on top of the sintered layer as the entire print bed drops, and the lasers do another pass, fusing the single-layer of powder to the already solid layer below. Thus prints are completed layer by layer, exactly as in the other printing technologies that we covered, except the end product is a solid object that’s been drawn by lasers, encased in all of the powder that wasn’t fused.
This method provides total support for the print in question, so nearly any imaginable geometry can be printed using SLS printing. It is also possible to use any material for SLS that is capable of being powdered and fused with heat, including thermoplastics, covered in my previous post, as well as steel, aluminum, titanium, and other metals and alloys. Prints produced in this way are very nearly as strong as solid-cast parts, which means that it’s possible to 3D print mechanical parts that are directly usable in engineering projects via SLS printing.
Layer height and resolution in SLS printing is completely determined by the resolution of the powder being fused, but is typically on par with SLA printing, averaging around .1mm layer heights. Another similar technology is electron beam melting (EBM) that uses high energy electron beams to melt powdered metals in order to produce 3D objects. The use of electron beams allows for even higher precision than lasers, allowing for up to .05mm layer heights, which is nearly unheard of by any other method.
Laminated Object Manufacturing
The last specific type of 3D printing that I’ll describe is, in my opinion, particularly clever. Laminated Object Manufacturing takes thin materials like paper or plastic sheets, cuts them to a specific shape, and then uses adhesive to glue one layer to the next. The most well known of these types of printers is manufactured by a company called MCor Technologies. Their printer uses normal, ordinary copy paper as its substrate, cutting one sheet at a time into the appropriate shape for the given layer, and then using paper glue to laminate the individual layers together. The high-end model of the MCor printer includes a full-color inkjet printhead inside, to allow for full color 3D prints to be created from very inexpensive raw materials; literally paper, ink, and glue.
Other 3D Printing Types
Numerous other 3D printing technologies are available, many that are patented and limited to a single company. For example, 3D Systems uses a type of 3D printing methodology that they call Color-Jet Printing (CJP) that uses two different materials that are combined using a sort of high-end inkjet printer in order to create the solid end-product. This patented process allows them to print in materials like food-grade ceramic. 3D Systems also makes a 3D printer that is capable of printing in sugar, called the ChefJet, and the high-end model, the ChefJet Pro can print edible 3D models in full color.
Editor's Note: This is the third of a series of posts excerpted from Jason Griffey's Library Technology Report "3D Printers for Libraries."
The substrate for FDM printers are almost exclusively some form of thermoplastic that is delivered in an extruded wire-like form on a spool. It is usually called “filament” in the generic. The two common diameters for use in FDM printing are 1.75mm and 3mm, and a specific diameter is called for by the print head being used for the printer in question. A printer that uses 1.75mm diameter filament won’t be able to use 3mm without retrofitting the hardware for the difference, and vice versa. Slightly more common, the 1.75mm diameter is used by Makerbot Industries, the most popular manufacturer of FDM printers.
In later postss, when I write on the different printer types and manufacturers, I’ll note what type of filament they are capable of printing, because that turns out to be a major limitation and purchasing decision factor.
The original fused deposition printers almost exclusively used ABS (Acrylonitrile butadiene styrene) as their substrate for printing. ABS is nearly ideal from a material property point of view for rapid prototyping in plastic, as it’s strong, slightly flexible plastic, which extrudes cleanly at between 220° and 240° celsius. ABS is the type of plastic used in Lego bricks, and is one of the most commonly used industrial/commercial plastics.
For FDM printing, ABS requires a heated print bed to ease the thermal shock for printing. Heating the print build plate aids the plastic in both adhering to the plate for stability, and in preventing cooling too quickly, which leads to thermal deformation, or a sort of curling separation. ABS is sensitive enough in this arena that many people who print ABS learned early on that enclosing the printer was a way to increase the stability of prints because it regulated the temperature around the printer. I soon discovered in my printing experiments with an early Makerbot printer (Replicator 1) that even a strong breeze blowing in the wrong place (across the print bed) could wreak havoc. Higher end printers will have an enclosed print area, while less expensive ones don’t.One of the advantages of ABS is that it dissolves in acetone. Acetone dissolves ABS completely, but used sparingly it can act as a glue to fuse two ABS printed pieces together permanently. Acetone is also used to make a “glue” for print beds, to help in making the print bed sticky for the initial printed layers. Acetone vapor is heavier than air, and some people have used this to build acetone vapor baths that act to smooth the edges of layers of an FDM ABS print.ABS has caught some bad press recently, as the potential effects of off-gassing of the heated plastic and microparticulate effects are studied. As a petroleum based plastic, ABS does produce a distinctive stink when printing. Fumes have been reported to cause headaches, and studies link ABS fumes to olfactory loss; one study that found ABS printing released high volumes of ultrafine particles that could be dangerous when inhaled. These are preliminary studies. Most haven’t been repeated, and the science is still rough on the health effects here. But if you need to print with ABS, it may be a good idea to take venting into account.
PLA (Polylactic acid) is the second most popular printing substrate for FDM printers. A bioplastic, PLA is made from corn, beets, or potatoes. It is compostable in commercial compost facilities (the heat and bacterial action isn’t high enough in home composting to break it down). It melts at a much lower temperature than ABS (150-160°C), but is typically extruded at a higher temperature, anywhere from 180-220°C depending on the PLA itself. Because of it’s lower temperature, it’s not suitable for uses that involve high temperatures and direct sunlight. PLA is also very different than ABS in term of fragility. Far more crystaline, PLA shatters or cracks more readily than ABS, whih instead will deform under pressure.
However, Makerbot and other major manufacturers are now starting to go with PLA as their primary printing plastic. PLA doesn’t require a heated bed for adhesion or thermal curling reasons, which lowers the price of the printers that use it. As well, it’s far more thermally stable during printing than ABS, and much less likely to warp or curl due to errant breezes. It is possible to reliably print PLA without needing to enclose your printer, which can be a huge benefit in many circumstances.
The other significant advantage is that PLA is far more pleasant when printing than ABS. Because it is a bioplastic, when heated it smells like waffles or syrup, and not like an oil spill. It also hasn’t been linked to any types of medical issues from being heated, although the study of all these plastics is young when it comes to 3d printing specifically.
One of the other advantages of PLA is that it’s available in dozens and dozens of colors, including both opaque and partially transparent, as well as a couple of colors of glow-in-the-dark. It also is available in a flexible form, which can produce prints that are almost rubber-like in consistency.
If you are printing in a library setting, I would suggest focusing on PLA. Between the reliability and the ease of working with it, it’s a far better choice than ABS for printing in a public space.
Once you get beyond ABS and PLA, you’re in the realm of specialized plastics that are used for specific properties rather than for general 3D printing. More of these appear every day, practically, but generally they fall into a couple of categories: dissolvable support material, specific material qualities that are needed, or non-plastic powder suspended in a thermoplastic resin. I’ll describe the most common of these below.
High Impact Polystyrene or HIPS is a plastic filament used for dissolvable support structures in FDM printers. It extrudes at around 235°C and has a set of material properties that make it similar to ABS. The main difference is that HIPS is completely soluble in a liquid hydrocarbon called limonene. This means that if you have an FDM printer with more than one print head, you can extrude ABS from one and HIPS as a support material from the other, and sit the final printed model in a bath of Limonene. The HIPS will dissolve away, leaving only the ABS behind, thus allowing for nearly impossible geometries to be printed, including moving ball bearings and more.
There are at least 4 types of nylon currently available for use in FDM printers: Nylon 618, Nylon 645, Nylon 680 and Nylon 910. These vary in their color from medium transparency to fully opaque white, and all are extraordinarily strong as compared to other FDM substrates. They are also very resistant to solvents and such, although they are dyeable with acid-based dyes for coloring.
Nylon as an FDM printing material is more expensive than PLA or ABS. The major reason for using them would be for specific material properties (resistance to specific chemicals) or due to the need for FDA approved materials, as both Nylon 680 and 910 are undergoing FDA approval for use, something rare in the 3D printer world.
T-Glase is a brand name for a filament composed of Polyethylene terephthalate. Of all 3D printer filaments, it is the most glass-like. Nearly transparent, especially at small sizes, it could easily be mistaken for glass. At larger sizes it is still very light-transmissive, if not fully transparent. T-Glase prints at around 221°C, on a heated bed, but is very stable and resistant to curling.
LayBrick & LayWood
Another type of printing material for FDM printers, these fall squarely in the experimental realm. They are made by a single manufacturer, and are both a sort of hybrid filament, with a powdered material being supported inside a resin. In the case of LayWood, fine wood particles are suspended in a thermoplastic resin, and in the case of LayBrick, it would be very finely crushed chalk and other minerals suspended in the resin.
Both LayBrick and LayWood have the interesting property of variability in appearance depending on the temperature at which they are printed. LayBrick can range from a very smooth, almost ceramic feel, to very rough sandstone, just by increasing the heat of extrusion. For very smooth, you print at a low temperature (165°C to 190°C) and then going up from their to around 210°C will render the printed part more and more rough. For LayWood, the difference is in the appearance of the final product. By increasing the temperature, you get darker and darker wood grain from the output, so you can actually vary the look from light to dark wood (or, if you have a printer that supports variable temperatures during a single print, you can get different colors in a single print by varying the temperature).
One of the risks, however, with both of these is that the filament isn’t uniform in construction, which means that it’s possible to clog your extruder if the nozzle opening is smaller than the particulate in the filament itself. FDM printers nozzle openings range from .35 to .5mm, and on the lower end of that, especially with the LayWood (organic particles are harder to ensure regular sizes than inorganic particulate) you risk clogging a nozzle. I know 3D printers that have clogged even at .4mm nozzle using LayWood. For printing these sorts of filaments, the larger the nozzle the better.
Still very experimental, polypropylene (PP) offers the possibility of food-grade 3D prints. Polypropylene should work with any FDM printer, at an extrusion temperature of 201°C and a heated print bed set to 90°C. It looks like PP is only really available in black.
Challenges with Fused Deposition Modeling
Most of the issues with FDM printing are related to the fact that it’s a very mechanical process, and tuning the printer is key. The most sensitive aspect of the process is the relationship between the extruder and the build plate. Because the printhead has to extrude an even layer of plastic onto the build plate, it’s necessary that the build plate be perfectly flat relative to the nozzle. If there is any warp or uneven-ness, you’ll get uneven attachment to the plate or other forms of print failure. This is the most common issue with FDM printing, especially with new operators. The first question to ask if a print fails is: “Is my build plate level/”
And prints will fail. FDM printing is a complicated mechanical process, and while you can tune a FDM printer to be very reliable, at some point you will have a failure and will come back to a print that looks like someone poured plastic spaghetti on your build plate. This is normal. Recalibrate, re-level, and try again.