What you need to know before using a 3D printer and how to slice a model ready for printing.
3D printing, as the person off the street knows, is mainly about producing interesting plastic thingies. 3D printing in the real world, however, is part of mainstream manufacturing and is also known as Additive Manufacturing. Prior to Additive Manufacturing becoming more common, the normal way to make something with any kind of precision was with Subtractive Manufacturing. So, what exactly does all this stuff mean?
Subtractive manufacturing has been around since Early Man started rubbing sticks against rocks to make them sharp or knocking off bits of flint from a stone with another stone to make axes, hammers or arrow heads. The work that a grindstone does to a metal blade was reversed when clay was shaped on the potter’s wheel or wood was turned. The Industrial Revolution took the principles of wood turning to create metal Lathes and Mills, and the size of these machines rapidly scaled to make even greater machines. All of these machines had something in common – they all worked by removing material from whatever was being made.
In modern terms, subtractive manufacturing is an umbrella term for various controlled machining and material removal processes that start with solid blocks, bars, rods of plastic, metal, or other materials that are shaped by removing material through cutting, boring, drilling, and grinding.
Additive Manufacturing in modern terms is recent. Clay has been added to moulds for centuries, and it can be argued that processes such as Injection Moulding is Additive and has been available since India Rubber was first used. True Modern Additive Manufacturing is basically 3D Printing. Additive manufacturing (AM) or additive layer manufacturing (ALM) is the industrial production name for 3D printing, a computer-controlled process that creates three dimensional objects by depositing materials, usually in layers.
Modern machine tools allow the manufacture of complex and precise new tools and machines. The old lathe used for wood was improved to work metals and this evolved into mills and other machine tools. As computers became smaller, faster and more available to Industry and semiconductor technology led to new sensors, new Computer Numerical Control (CNC) machines were developed. The precise control that CNC brings to the tools that subtract material from a workpiece has been used to create something entirely new – the ability to precisely control where to put additive material. This fundamental change has recently exploded in the world of manufacturing and created entire new industries.
In 1971, Johannes F Gottwald patented the Liquid Metal Recorder, U.S. Patent 3596285A, “a continuous Inkjet metal material device to form a removable metal fabrication on a reusable surface for immediate use or salvaged for printing again by remelting.” This appears to be the first patent describing 3D printing with rapid prototyping and controlled on-demand manufacturing of patterns.
On 2 July 1984, American entrepreneur Bill Masters filed a patent for his Computer Automated Manufacturing Process and System (US 4665492). This filing is on record at the USPTO as the first 3D printing patent in history; it was the first of three patents belonging to Masters that laid the foundation for the 3D printing systems used today. Early 3D printers used different techniques including Plastic Extrusion, Laser Sintering and Stereolithography. 3D Printers in the 1980s cost around US$300,000
In 2009, the Fused Deposition Modelling Printing Process (FDM) patents expired. 3D printing becomes available for an affordable price. Additive Manufacturing has been used for about the last 40 years in Industry, but since the Patents expired in 2009, this has opened up 3D printing to the masses. Now affordable 3D printers are available for a few hundred dollars in Australia.
So, we now know a little about 3D printers and their history. How do we go about actually doing something with them?
The model we created in Tinkercad in the last article is what we will 3D print, but there is a bunch of stuff we need to know about first. It helps if we know exactly how 3D printing actually works from a technical point of view as it will affect the decisions we are going to make next. The decisions we make will not be difficult, but they are easier if we know a few things. So, let’s start with types of Printing, as not all 3D Printers are the same.
When it comes to 3D Printers, there are basically three different main methods of Printing, and a few popular sub-types of each of these. The three main methods are:
The first of which is sintering whereby the material is heated without being liquified to create complex high-resolution objects. Direct metal laser sintering uses metal powder, whereas, selective laser sintering uses a laser on thermoplastic powders so that the particles stick together.
2. Selective Laser Sintering
The second AM technology fully melts the materials. This includes direct laser metal sintering, which uses a laser to melt layers of metal powder and electron beam melting, which uses electron beams to melt the powders.
The third broad type of technology is stereolithography, which uses a process called photopolymerisation, whereby, an ultraviolet laser is fired into a vat of photopolymer resin to create torque-resistant ceramic parts able to endure extreme temperatures.
The list below gives a brief description of the different common types of Additive Manufacturing. The one that we are interested in is the Material Extrusion method, specifically plastic extrusion. Vat Photopolymerization is also a common method available to Makers, and we will talk about the Pros and Cons of both.
With credit to autodesk.com.au, additive manufacturing can encompass multiple processes, depending on the hardware, material requirements and product application.
A vat of photopolymer liquid is cured by focused UV light that builds parts layer by layer for a high-detail surface finish.
A powder substrate is hardened when the printing head deposits a drop of binding fluid in a layering process. Includes full-colour prototype fabrication.
Used where surface finish and form testing are needed; a printhead lays down successively solidifying layers of UV curable material to form prototyped designs.
Fused deposition modelling is a common 3D printing process in which a heated nozzle extrudes a plasticised material to form products from a sliced CAD model.
POWDER BED FUSION
Laser or electron beams quickly fuse layered powder material, such as various metals, together. This technique is used for circuits, structures and parts.
Ribbons of metal or paper are bonded through ultrasonic welding or adhesive, respectively; the finished shaping is completed through further material removal processes.
DIRECTED ENERGY DEPOSITION
Repairs or adds to existing components by using a multi-axis nozzle to extrude laser-melted material, commonly metal powders, onto the printing surface.
Using generative design and simulation software to produce complex metal parts helps manufacturers get more value from proven metal casting processes.
Let’s now talk about Vat Photopolymerization and Material Extrusion 3D Printing. Vat Photopolymerization, or Resin Printing, is a process where a liquid is hardened with UV light or a Laser, or occasionally both, layer by layer to build up the finished model. The process is finished in very high detail but requires quite a lot of post-processing (more on this later). Material Extrusion 3D Printing is usually some type of Plastic, but can also be plastic or metal embedded resin that is later “cooked” in an autoclave to give it strength. The plastic extrusion method is the common one that is generally available to Makers.
This printer shown here is a popular Vat Photopolymerization printer and the associated post-print Washing Station. While it is possible to do without the washing station, sane Makers will have both.
It’s like you CAN hang out the washing as we do mainly in Australia, but in Europe and America, it is mainly throw it in the Dryer for convenience. In the case of 3D Printers, you actually WANT to do it the European and American way – use the machine. This is because of some of the chemicals used in these printers are very effective, but also very nasty to Carbon Based Human Lifeforms.
Obviously, not all Resin printing is bad. Many companies have tried hard to make their printers as safe as possible and environmentally friendly. This has mainly been done by trying to use plant-based materials to create the resins so that they break down more easily into safe by-products.
You could argue that solvents like Acetone (Nail Polish Remover) are also organic and so is safe to use, but according to the Materials Safety Data Sheet, Acetone is “Highly Flammable Liquid and Vapour”; “Causes Serious Eye Irritation”; and “May cause Drowsiness or Dizziness”. These statements are also found on Isopropyl Alcohol, another common solvent used in 3D printing available to Makers.
Material Extrusion printers are also somewhat guilty as they also use these solvents commonly. These printers also have other issues, as most Resin printers are pretty much self-contained because they need to have a bath of resin to work; Material Extrusion printers are often open and so have other safety hazards like Pinch Hazards or Hot Components.
The point of this article is not to try to scare people off from using these wonderful machines. The point here is that fore-warned is fore-armed. If you know what the issues are then you are more likely to protect yourself, be careful and be less likely to have an accident.
Surprisingly, there is little information available from mainstream Safety Organisations about 3D Printer Safety other than quite general information. This is mainly because the 3D Printing Industry as it stands is very young and not a lot is really known about it. My searches of Australian Safety Sites, e.g., WorkSafe, came up with little specific Safety information. Similar searches outside Australia found that even American and European OHSA Organisations didn’t have much to say. Most of the Safety information I did find was predominately from the Printer Manufacturers themselves and a handful of websites that specialised in 3D Printer information. The other source of Safety information was places like School and University websites where 3D Printing Courses were run.
So, let’s look at some of the more common Safety information out there in Cyberspace about 3D Printers in General. Obviously, if you have a specific Printer then you should scan the Manual for this stuff to help stay safe.
We will start with this small list:
- The generation of ultrafine/nano-sized particles;
- Mechanical hazards from moving parts;
- High voltage;
- Ultraviolet light; and
- Chemical vapours (ex. styrene, acrylonitrile, or formaldehyde, etc.) depending on the media being used.
You may be aware of reports in the Media about nasty diseases like Silicosis, Asbestosis and Coal workers' pneumoconiosis (CWP). All of these diseases are associated with breathing in small particles.
Silicosis is a big issue at the moment with Builders, as many of them are being struck down from working with those artificial stone benchtops in Kitchens. Asbestosis is a worry because of Home Renovations by amateurs especially over the past 20-years as many homes built before the 1990s had asbestos products in them. CWP is what used to be called Black Lung, and the Coal Miners have known about it for centuries.
Ok, so now that I have scared the living Snot out of the readers, what is the issue with 3D Printing? Well, as the plastic from the filament heats up and is layered onto the print surface, tiny pieces of micro-plastics can be thrown up into the air and breathed in. These micro-plastics can then become embedded in the lungs and cause breathing issues. This is a well-known problem with frequent 3D Printer users, and anecdotal evidence of Makers working and sleeping in the same room as their printers and developing breathing issues are not uncommon.
There is good news, however. This issue is a known issue by the Industry, and while some of the cheaper 3D Printers out there are very basic, the more expensive ones will come with an enclosure around the Printer and a ventilation system with a HEPA Filter. HEPA is a type of pleated mechanical air filter. It is an acronym for "high efficiency particulate air [filter]" (as officially defined by the U.S. Dept. of Energy). Even without a HEPA filter, if 3D Printers are used in well ventilated areas and exposure is protected or limited, say with an N95 or P2 Respirator, then it is pretty safe to be around them. Sleeping with a 3D Printer in a small bedroom with little ventilation is NOT recommended, but many people actually do this.
Hot to touch
While Heat is not as much of an issue with Resin printers, it still can be a problem. After all, many Resin printers use Lasers instead of UV lights. That being said, more of an issue of heat is with Material Extrusion printers as this is the actual method they use to create the layers of material – they heat it up and then lay the molten material onto the previous layer. Depending on the type of material you print with, the Hot End of the printer will need to be heated to melt it.
One of the most common materials used is Poly Lactic Acid (PLA) which needs to be extruded at temperatures between about 180-210°C. Carbon Fibre reinforced plastics need temperatures well over 300°C. This means that when you poke your fingers around the hot bit – it WILL be HOT! Luckily many of the plastic Extruders (the Hot bits) are well insulated on most printers but it is still possible to get fingers near them.
Also, the Build Plate of many printers is heated to allow the deposited material to “stick” so that it doesn’t move and ruin the precision. PLA printers only need temperatures around 60°C, which is uncomfortable for some people, but Build Plate temperatures of over 100°C can be generated by most printers, even without exotic Carbon Fibre filaments. Fires are certainly NOT unknown to occur with 3D Printers.
Anything that has moving parts will often have areas where “pinch points” occur that can pinch, crush, entangle or grab. It is unlikely that your average home 3D Printer is going to rip your arm off but getting a finger caught between two metal gears or plates accidentally will not tickle either. If you trap a finger between the Build Plate and something it may or may not hurt much, but if the Build Plate is a Glass type it may shatter and cause other hazards. Anything that moves can be an issue – so be aware of it.
High voltages are not common in most Maker 3D Printers, although some of the bigger ones do start using 3 Phase power. We already know that 240VAC can kill you under the right circumstances. 3D Printers operate mainly on 240V and convert it to DC voltages, so the normal issues with Electrical equipment apply. Bear in mind that there are many “open” areas around printers with wires sticking out. Putting fingers in the wrong place can give you a nasty shock sometimes. Most machines are well insulated and protected from this sort of thing but some DIY style printers can be a little less well protected.
UV or Ultra-violet light is more of an issue with Resin Printers but it still can be a big deal. The way a resin printer typically works is that the light from a UV Laser is focused on the point that is to be printed to give enough energy to make the resin react. Everything is Hunky Dory if it all works properly, but a fault in the machine can cause UV Laser light to be focused outside the build area.
Most Resin Printers have a Safety Shield to try and reduce these problems, but it can happen. Turning on the Laser when there is no Resin in the Printer can be an issue if your head is inside while doing some maintenance. Some Material Extrusion printers extrude a paste of Resin with other material embedded inside and use a UV light to make it harden. These tend to be Mid-Range or High-end Printers but again, they are out there.
This is a good one, because many people just don’t seem to realise that if you apply enough heat to ANYTHING it can break down, and some breakdown particles are VERY nasty. In the future article about Laser Cutters, we will learn about substances with Chlorine in them are an issue. 3D Printers also have this problem simply because you are applying heat to materials that causes change. If the change is minor then often it isn’t an issue, but some substances must change in order to get the desired end result.
Remember that “New Car Smell” people talk about? Well, that smell is basically all of the solvents from the glues and the residual chemicals used in manufacturing of new parts that leach out over time. Not only is it unavoidable but it is often necessary as these new parts strengthen to full strength when the leaching process has finished.
Well, some of the materials that are used in 3D Printers are exactly the same as those used in new cars. ABS plastics are one of the most common materials used in 3D printing, especially at the Maker level. One of the reasons that there are so many different materials used in 3D printing is that different materials have different physical properties. ABS is very tough and hard but can be brittle. PLA is softer and more flexible.
Other exposures to chemicals are through the cleaning materials used in the processes. We have already mentioned Acetone and Iso-Propyl Alcohol and there are others.
By now you are probably wondering if you really WANT to get involved with this 3D Printing animal. I must admit that many of these things hadn’t even crossed my mind when I started learning about them on my short course a few months ago. All is not lost. While much of this stuff sounds really scary, as long as you are aware of the potential issues, and you take actions and responsibility, and you follow simple guidelines – 3D Printers on the whole are actually pretty safe.
In an ideal world, the 3D Printer Manual will have a comprehensive list of potential safety issues, warnings and procedures, and the users will all have proper training available to them, normally via YouTube or videos on the Manufacturer’s website. Users will also wear proper Personal Protective Equipment, including Safety Glasses, Protective Gloves, Steel Caps and Protective Clothing.
As I said, in an “ideal world”. I also noticed that when people mow their lawn they ALL wear Steel Caps, Chaps, Long Sleeve Shirts, Leather Gloves, Hearing Protection, and Safety Glasses. Some wear Helmets too!
Funny how the local Lawnmower Man DOES wear all this stuff, but when you do it yourself you DON’T. All I am saying is – be aware and act accordingly. I can’t MAKE you do this stuff but it isn’t silly either.
We are finally up to the bit where we look at HOW do we actually go about 3D Printing an object.
Printing an object
First, we will have to get a File Copy of our Object we want to 3D Print. Open up Tinkercad in your Browser and open the Object you created last time. In the Top Right corner just above the Ruler you will see a Button marked Export. Right-click this button and you will open up the following screen.
We will be clicking on the “.STL” Button in this case so we can create a Stereo Lithography File. Save it somewhere you can locate it as we will be using it soon.
Before we continue, we will need to get and install some additional software. Not all 3D Printers speak the same “language”. Stereo Lithography files might be the Industry Standard for 3D Printers but there is a certain amount of Pre-Processing we will need to do to our file before we can print it. What we have created so far is the solid version of what we want printed, but in order to actually print it, we will need to set up the 3D Printer with the appropriate settings, then process our STL file so that it can then be printed using those settings. One of the most important things that need to be done is to create the actual layers the printer will print on each pass of the Extruder. Depending on the printer, the material, and the quality of the print, these basic settings will be different. What we need is some Pre-Processing software to do this for us.
The software we will be using is called a Slicer, since that is its primary job – to slice the STL model into layers for the Printer. There are many Slicer programs on the Internet. We want a Good, Easy to Use, Free one. We will be using a Slicer called Cura, by Ultimaker, which is a 3D Printer Manufacturer. It was originally designed for Ultimaker Printers but other Printers can be loaded or created. This means it is very versatile software as many machines can use it. To install Cura, first, go to the Ultimaker Homepage at www.ultimaker.com
Once at the homepage, hit Software and navigate to the Ultimaker Cura software page:
Download and install the free copy of Ultimaker Cura 5.0.0 from here.
Again, I am assuming that if you are keen enough to learn about 3D Printing you are able to download and install software. Install the software and fire it up and you should end up with something resembling this screen.
For this Tutorial, we will be using a 3D Printer called the Artillery Sidewinder X1, so we will set up Cura for that one.
Follow the Setup prompts until you get to this screen. Creating an Account is optional, and I didn’t bother, so Create one if you want to, otherwise, just Skip this screen.
The screen that we actually want is the next one.
So, if you already have a 3D Printer, by all means, set it up. You may have to go digging for it online to get the setup to correctly work, but most popular 3D Printers are either already supported by Cura, or can easily be found. For now, click on the Add a non-networked printer. Then Scroll down until you see Artillery, open the arrow and select the Artillery Sidewinder X1.
This will bring you to the Settings page for the Artillery printer. We will use Default Settings, so just click through until we have finished the install Process. You should now have Cura open to a Blank Build Plate screen like this:
Now that we have our Slicer software open, we can import our STL file we want to print. To do this, left Click on File, select your file from where you saved it and open it as you would with any other file in any other software. With our Tinkercad file it should end up like this:
We are now almost at the point we can 3D Print this object, just one more step to go. 3D Printers are part of the Computer Numerical Control (CNC) Family of machines. This means that they use a Standard language to tell them what they have to do and how. This Language is commonly known as G-Code. There are many ways you could print this object, you could simply start at the top line and print to the bottom continuously, turning the filament on and off as required, but this is not very efficient or very fast.
What the Cura software actually does is Slice the STL into layers, and then path finds the best and fastest way to actually print the object. The Print will be much better finished if long strips of plastic filament are laid down. The reasons for this will be discussed in the next article. For now, we are just going to use the Default Settings and create the File we will feed the 3D Printer containing the G-Code instructions. Creating the G-Code file is easy, simply click on the big button that says Slice, and save it to a USB.
As you can see, this file will take 2 hours to print on this printer, and will use 19g or 6.22m or filament. All that is now left to do is upload the file to the Printer and press the Go Button.
At this point, we have reached a good point to finish for this installment. While our 3D Print is on the printer being created, we will look into some of the problems that you might run into when using this technology and how to fix them. In the next article, we will look at those problems, why they occur and what you can do about it. We will also talk about the different types of filaments and why you might use them. Many of the issues can be easily fixed by tweaking the Cura Settings.