How to Choose a 3D Printer
by Samir D'Monte, CEO, Clarity 3D Printing
There is a bewildering array of printers to choose from. This article describes consumer grade 3D printers. For more information, see our page on consumer vs. industrial 3D printers. In short, consumer grade printers usually cost less than Rs. 10 lakh (US$20,000) with some exceptions. They are cheaper, have less resolution, and are not built as robustly as industrial grade 3D printers, many of which can run 24 x 7 x 365. Industrial grade machines cost from about Rs. 35 lakh (US$ 60,000) to 10 crore (US$ 2 million).
Some specialised industrial machines can also handle advanced materials like metal and ceramics, which consumer grade machines cannot. Every 3D printer works with one type of printing technology, and with one set of somewhat similar materials. Consumer grade machines can only work with plastics.
When selecting a machine for your use, consider the following factors:
Printing Technology
This is the most basic factor to consider. 3D printing is actually a phrase that is used to describe a range of different technologies. Consumer grade printers, fortunately, work on one of these two technologies:
FDM based PrintersFDM stands for Fused Deposition Modelling, also called FFF, Fused Filament Fabrication (one manufacturer has patented the term FDM, so the others have to find work-arounds). In FDM technology, the machine takes a thin plastic wire called filament as the input raw material, and sends it to a print head, which essentially melts the plastic, and moves in 3 dimensions to form horizontal layers of plastic, which stick to each other. It repeats this process, building layer upon layer to create the whole object.
FDM printing is affordable, great for general purpose parts, and for large parts. Its resolution however is a little lower than other technologies, since the plastic has to have a minimum thickness. Generally, these machines can produce horizontal layers from 100 microns to 300 microns thick (0.1 to 0.3mm). The layers are visible to the eye, and the parts can feel slightly rough to the touch. |
Resin based PrintersThese machines take a light-sensitive liquid called a resin as a raw material. The printing process can be called SLA, or stereolithography, which means writing with light (the A stands for apparatus). These resins actualy turn from liquid to solid when exposed to light. In this process, the machine has a tray filled with resin, and uses a light source such as a laser to "draw out" the shape of the object, one horizontal layer at a time. The areas of the liquid exposed to light turn solid, while there is no change in the remaining areas. The machine then moves the part vertically, and builds another layer touching the previous one, repeating this process until the entire part is built.
SLA machines produce smooth parts with lots of fine details, but the machines and raw materials (resin) are expensive. They also limit the part size; it is difficult to find a consumer grade SLA machine that can make a part larger than 8" in any dimension. |
Build Volume
The build volume is the size of the largest part the 3D printer can build. For most printers, it is cuboidal in shape, but for a certain class, called Delta 3D Printers, it is cylindrical. The build volume can be filled with many small parts or one large part during a build. If your part is larger than the build volume of your machine, you will have to make it in parts and join them with glue or screws.
So the build volume of your machine needs to be a little larger than the size of your largest part. For example, jewellers need very small volumes, as a size of a 75mm (3") cube can produce perhaps 30 small rings at a time. Architects, on the other hand, require much larger models, and for them, a machine with a build volume of 300 x 300 x 300mm (12" x 12" x 12") may be too small.
Keep in mind that the build volume of the machine greatly affects the price of the machine, so a machine that can produce a 600mm (2ft) long piece could be eight times as expensive as one that does a 1 foot long piece. Also, as the size increases, the amount of material consumed increases dramatically. A good quality FDM 3D printer that costs about Rs. 3 lakh (US$ 5,000) will have a build volume of approximately 230 x 200 x 150mm (9" x 8" x 6"), whereas a large machine of 1 x 1 x 1m may cost over Rs. 40 lakh (US$ 75,000).
So the build volume of your machine needs to be a little larger than the size of your largest part. For example, jewellers need very small volumes, as a size of a 75mm (3") cube can produce perhaps 30 small rings at a time. Architects, on the other hand, require much larger models, and for them, a machine with a build volume of 300 x 300 x 300mm (12" x 12" x 12") may be too small.
Keep in mind that the build volume of the machine greatly affects the price of the machine, so a machine that can produce a 600mm (2ft) long piece could be eight times as expensive as one that does a 1 foot long piece. Also, as the size increases, the amount of material consumed increases dramatically. A good quality FDM 3D printer that costs about Rs. 3 lakh (US$ 5,000) will have a build volume of approximately 230 x 200 x 150mm (9" x 8" x 6"), whereas a large machine of 1 x 1 x 1m may cost over Rs. 40 lakh (US$ 75,000).
Materials Used
Materials for FDM PrintersFDM printers work best with a material called PLA, or polylactic acid. This filament gives consistent results, and works well for most printing applications. If you are from a chemical or plastic production industry, you may need other materials with different properties. One must remember that all FDM machines need a thermoplastic that melts at a temperature of about 200 to 300 degrees centigrade. Other material options include ABS, which is widely used in the injection moulding industry, but is a little more difficult to work with, as it has a higher shrinkage factor than PLA.
Most filaments come in either 1.75mm or 3mm diameter - check which one your machine uses - and have a wide range of colours. Several 3D printer manufacturers offer a range of materials, which may seem tempting to the user, but one must remember that every material will require the user to change the machine settings, and this is not as straightforward as it may sound, because there is not always good information on which settings need to be changed for each material. Printing with less common filament at the wrong settings can cause the machine to have issues. Other materials include Nylon, stronger than PLA, but can have printing issues, PETG, a strong filament, PMMA, an acrylic-like material that can be transparent, laywood, plastic with wooden fibers embedded in it, and laybrick, plastic with a chalk-like material embedded in it. It is also possible to have flexible filament, but this does not work in all machines. If one is a beginner to 3D printing, or is just concerned with making one's designs leap off the computer screen and into the real world, it is better to stick to one or two materials, and learn how to print well with them. If, however, you are from an industry that demands specific chemical or physical properties, and if you are willing to take the extra effort, it is possible to work with a variety of materials. If not, just stick to PLA. |
Materials for Resin based PrintersResin based machines have a smaller set of materials. Most manufacturers offer just 4 or 5 resins, some of which are harder and some softer.
An interesting option in resins are castable resins. These can be used in a process called investment casting, which means that the 3D printed item can be used to create a mould in which liquid metal can be poured, making a metal component. This process is commonly used by jewellers, who can convert a digital design for a ring into an actual ring in gold or silver using this two-step process. Resins are usually available in a limited range of hues, most often black, white, grey, and translucent. |
Ease of Use
This is a very important factor, as not all machines are created equal. Some manufacturers have spent a lot of time making life simple and clear for their users; others have not. A good machine will have:
Cheaper machines can be quite difficult to use; they use third party open source software that may require you to speak to the machine through lines of code, and read bulky training manuals. This is why they are cheap.
- advanced software that allows you to print easily and quickly while giving you control over print quality
- a good screen on the machine that guides the user through every step, such as changing filament, or adjusting the extruders (print heads)
Cheaper machines can be quite difficult to use; they use third party open source software that may require you to speak to the machine through lines of code, and read bulky training manuals. This is why they are cheap.
Reliability
We have learnt through hours and hours of printing that some machines are reliable, and others are not, irrespective of what the manufacturers claim in their websites and brochures! Speak to our sales team to find out more.
For FDM Machines - Single vs. Multiple Extruders
The print head of the machine is called the extruder. It is definitely the most important part of the machine. The rest of the machine is only there to support the extruder and move it from place to place.
Machines can have more than one extruder. In a dual extruder machine, one can print with 2 different materials in the same build, or with 2 different colours in the same build. This has one advantage: one can print a support material for prints with complex geometry. If one is printing an architectural model with a horizontal slab, this will not print well because the melted plastic has nothing below it to hold it up. The solution is to create a support structure below it in a different material, called a support material. The print will then have 2 materials. Once it is finished and is out of the printer, the supports may be removed in two ways. They may be removed by hand, or, if they are made of a soluble material, the entire piece may be dunked in water or a solvent for a few hours to completely dissolve the filament.
Support material filaments are available: PVA filament, which dissolves in water, and HIPS, which dissolves in an orange-juice like solvent called D-Limonene.
Multiple extruders do not mean that the machine will print one object faster! They are used for multiple materials, or multiple colours. Each extruder is connected to one roll of filament. Some machines support 3 or 4 extruders.
However, there are some disadvantages to multiple extruders:
If one is a beginner, and wants a simple, reliable machine, then it is better to stick with a single extruder machine. If one wants parts with greater geometric complexity, or wants multiple colours in a print, and is willing to spend some more time and effort adjusting the machine, then go for multiple extruders.
Machines can have more than one extruder. In a dual extruder machine, one can print with 2 different materials in the same build, or with 2 different colours in the same build. This has one advantage: one can print a support material for prints with complex geometry. If one is printing an architectural model with a horizontal slab, this will not print well because the melted plastic has nothing below it to hold it up. The solution is to create a support structure below it in a different material, called a support material. The print will then have 2 materials. Once it is finished and is out of the printer, the supports may be removed in two ways. They may be removed by hand, or, if they are made of a soluble material, the entire piece may be dunked in water or a solvent for a few hours to completely dissolve the filament.
Support material filaments are available: PVA filament, which dissolves in water, and HIPS, which dissolves in an orange-juice like solvent called D-Limonene.
Multiple extruders do not mean that the machine will print one object faster! They are used for multiple materials, or multiple colours. Each extruder is connected to one roll of filament. Some machines support 3 or 4 extruders.
However, there are some disadvantages to multiple extruders:
- they are more difficult to adjust and caliberate
- when using both extruders in a print, the build volume of the printer reduces, as there is a centre-to-centre spacing between the two nozzles, and both nozzles have to fit within the same build volume.
If one is a beginner, and wants a simple, reliable machine, then it is better to stick with a single extruder machine. If one wants parts with greater geometric complexity, or wants multiple colours in a print, and is willing to spend some more time and effort adjusting the machine, then go for multiple extruders.
Heated Build Plate or Chamber
A heated build plate or chamber is a good feature to have for advanced users. It prevents warping of large, flat prints. It also makes it easier to work with ABS, which tends to warp more than PLA. Some machines have an enclosed chamber that is heated. In fact, all industrial grade FDM printers have this feature.
Features
While an onboard camera sounds like a frivolous feature, it actually is quite useful in practice, as one can give a print at the end of a working day, and monitor the print from home or anywhere else. Some machines, such as Makerbots, also allow you to remotely pause the machine or give a print. Wi-fi connectivity is also very useful, and makes printing from any machine very quick and easy.
Can the machine be used in my office, or does it need a workshop environment?
Almost all consumer 3D printers are desktop machines, meaning that they can be placed in an air-conditioned office environment without any problems. There may be some odours from melting filament or resins, but these are not harmful. Of course, you must check the machine specifications and user manual of your machine before using it.
