3D printer basics

3D Printing Basics: A Beginner's Guide

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Check out this comprehensive guide to 3D printing and 3D modeling basics. Learn about important terminology you should know, 3D printers, and extremely fast cloud CAD software.

Whether you are an up-and-coming college student or a veteran engineer, learning or revisiting the fundamentals of three-dimensional (3D) printing is extremely valuable. 3D printing isn’t just a futuristic dream anymore. Industrial designers often use 3D printing to create prototype scale models to test their design’s form, function, and fit. 3D printers are as versatile as ever with various features, materials, and applicable 3D software packages like Autodesk Fusion 360.

Designers typically have a design (or dream) in mind to begin. 3D printing helps bring that dream to fruition. This article discusses the fundamentals of 3D printing to help you go from dream to done in no time.

What is 3D Printing?

3D printing, also known as additive manufacturing, is printing a 3D object from a digital design. Unlike traditional subtractive processes, 3D printing is an additive process. It takes a solid object and then carves or reduces it into the ideal design. Essentially, the 3D printer uses a digital blueprint to mold a physical product. For example, some 3D printers use a heated material, like plastic, to create a layer on top of other layers, which eventually stacks up in three-dimensional space to create an object.

3D printing was introduced in the late 1980s but didn’t draw serious attention until the 1990s. As with any new technology, many people saw 3D printing as only possible in science fiction. However, 3D printing gained traction and is now being integrated into several industries.

3D printing Terms and Definitions

It’s helpful to understand the vernacular associated with the 3D printing process before diving into the wide world of additive manufacturing. Not every term can be listed or understood in one blog post, but the list below should help you kickstart your project.

Additive manufacturing: Another term for 3D printing. The process of adding materials to create a physical object.
Bed leveling: The process of leveling a 3D printer’s build plate.
Bowden extruder: An extruder type for FDM printers that has a separated hot end and extruder motor.
Computer-aided design (CAD): The process of designing parts or other objects in a digital environment before 3D printing.
Computer-aided manufacturing (CAM): The process of using software and computer-controlled machinery to automate a manufacturing process.
Curing: The process of using UV light to solidify liquid resin.
Digital light processing (DLP): A printer that projects light over an entire layer to cure the resin all at once.
Direct drive: This device is different from the Bowden extruder because the extruder motor sits on top of the hot end.
Elephant’s foot: A common problem where the first layer is distributed wider than needed. This problem can be solved by adjusting the 3D printer settings.
Extruder: A motor with gears that feeds filament to the printer’s hot end.
Filament: Material used in 3D printing.
Fused deposition modeling (FDM): A 3D printing method where material layers are fused together in a specific pattern.
G-Code: The language used to create commands for 3D printers.
Hot end: Consists of a heating cartridge and a thermistor to heat the filament.
Infill: This is the interior of the printed object. Infill patterns vary and help provide adequate internal structure to the printed object.
International Organization for Standardization (ISO): A worldwide standard of quality management for any organization.
Liquid crystal display (LCD): A printer that uses an LCD screen to mask a projector’s light or uses its own light to cure an entire layer at once.
Selective laser sintering (SLS): An industrial 3D printing process that uses a laser to fuse a thermoplastic powder to build prototype parts.
Stereolithography (SLA):A printer that uses a laser to cure liquid resin with pinpoint precision.
Striping: Striping is a common problem with FDM printers where individual layers become visible in the end product.
Thermoplastic: A type of plastic made of polymer resins that soften when heated and hardens when cooled.
Vat Polymerization: Resin-based 3D printing where liquid photopolymer resin is stored in a vat (unlike other printers that force thermoplastics through a nozzle). Subcategories of vat polymerization include stereolithography (SLA), digital light processing (DLP), and liquid crystal display (LCD).

3D Printers for Beginners

A 3D printer operates on the X, Y, and Z-axes:

The X-axis is the left-to-right movement.
The Y-axis is the front-to-back movement.
The Z-axis is the upward and downward movement.

The extruder is installed on the X-axis and feeds filament onto the build plate (print bed). The build plate is often heated and can adjust for leveling and temperature.

Types of 3D printers

There are several types of beginner-friendly printers on the market. The most common are FDM, SLA, and SLS printers. FDM printers are generally the cheapest option for beginners or homebrewing engineers. They are easy to maintain and filament to feed the machine is relatively affordable compared to the other two options. The downsides of FDM printers include clogged nozzles, difficult clean-ups, and striping.

SLA printers utilize liquid resin hardened by UV light to create a final product. These printers are great for intricate details (down to 25 microns) but cost a few thousand more than FDM printers. Disadvantages of SLA printers include clogged nozzles, limitations on available materials, and final products that can be potentially brittle.

Lastly, there are SLS printers. The main difference is that SLS printers use powder instead of liquid resin. These printers are the most expensive and generally cost over $50,000. However, they provide detail down to 16 microns and do not require infill patterns for stability. SLS printers can use materials other than resin, like aluminum, silver, or steel. Naturally, the biggest disadvantage is the price tag.

Choosing the right printer can be a difficult task, but the choice lies within the application. What will you use your printer for? Determining the printer’s application, cost, and size will all factor in your decision. Companies like Formlabs can provide specifications and factor individual costs for printers and associated equipment.

But a 3D printer is useless without proper software.

The Ideal Software for Beginners

Just like 3D printers, CAD software comes in various shapes and sizes. For example, Autodesk Fusion 360 provides an integrated, easy-to-use cloud CAD environment for beginners and experts alike. If you’re not ready to purchase a 3D printer or CAD software, consider utilizing Xometry’s industry-leading 3D printing services. Xometry provides an online marketplace for engineers or regular people to create or have something created.

Getting Started with Fusion 360

Consider Autodesk Fusion 360 when beginning your 3D printed project and join the more than 1.2 million innovators who have already switched to Autodesk’s software platform. Fusion 360 provides fast and efficient cloud CAD and a library of instructional content, tutorials, and additional information.

Go from dream to done with Fusion 360 today!

3D Printing Basics

3D printing is any one of many processes in which a part is additively created by introducing or bonding additional material. 3D printed objects can be geometrically complex and are ideal in a wide variety of manufacturing applications. Machines can cost anywhere from hundreds to millions of dollars and utilize a wide variety of technologies to print parts.

Introduction to 3D Printing

According to the Wohler's Report, the global 3D printing industry is expected to exceed $21B in worldwide revenue by 2020. Much of this growth comes from an explosion in using 3D printing in manufacturing, something previously thought impossible when the process caught on. New materials, processes, and companies are popping up by the minute, all making promises about the unrivaled properties their parts can achieve. All this adds up to an industry that can be hard to understand.

In this track, we're getting back to the basics. What is 3D printing? What are the main technologies out there today? How much do industrial 3D printers cost? You can learn all this in our 3D printing introduction.

- What is 3D Printing?
- 3D Printer Types & Technologies
- Understanding 3D Printer Cost
- Different 3D Printing Materials
- What is Atomic Diffusion Additive Manufacturing (ADAM)?
- What is Binder Jetting?
- What is Digital Light Processing (DLP)?
- What is Direct Metal Laser Sintering (DMLS)?
- What is Directed Energy Deposition (DED)?
- What is Electron Beam Melting (EBM)?
- What is Fused Deposition Modeling (FDM)?
- What is Multijet Printing (MJP)?
- What is Selective Laser Sintering (SLS)?
- What is Stereolithography (SLA)?
- 3D Printing Software
- 3D Printing Materials
- 3D Printing Process

3D printing for "dummies" or "what is a 3D printer?"

1 3D printing term
2 3D printing methods

2. 1 Extrusion printing
2.2 Melting, sintering or gluing
2.3 Stereolithography
2.4 Lamination

3 Fused Deposition Printing (FDM)

3.1 Consumables
3.2 Extruder
3.3 Working platform
3.4 Positioners
3.5 Control
3.6 Varieties of

4 Laser stereolithography (SLA)

4.1 Lasers and projectors
4.2 Cuvette and resin
4.3 Types of

3D printing term

The term 3D printing has several synonyms, one of which quite briefly and accurately characterizes the essence of the process - "additive manufacturing", that is, production by adding material. The term was not coined by chance, because this is the main difference between multiple 3D printing technologies and the usual methods of industrial production, which in turn received the name "subtractive technologies", that is, "subtractive". If during milling, grinding, cutting and other similar procedures, excess material is removed from the workpiece, then in the case of additive manufacturing, material is gradually added until a solid model is obtained. nine0048

Soon 3D printing will even be tested on the International Space Station

Strictly speaking, many traditional methods could be classified as "additive" in the broad sense of the word - for example, casting or riveting. However, it should be borne in mind that in these cases, either the consumption of materials is required for the manufacture of specific tools used in the production of specific parts (as in the case of casting), or the whole process is reduced to joining ready-made parts (welding, riveting, etc.). In order for the technology to be classified as “3D printing”, the final product must be built from raw materials, not blanks, and the formation of objects must be arbitrary - that is, without the use of forms. The latter means that additive manufacturing requires a software component. Roughly speaking, additive manufacturing requires computer control so that the shape of final products can be determined by building digital models. It was this factor that delayed the widespread adoption of 3D printing until the moment when numerical control and 3D design became widely available and highly productive. nine0048

3D printing techniques

3D printing technologies are numerous, and there are even more names for them due to patent restrictions. However, you can try to divide technologies into main areas:

Extrusion printing

This includes methods such as deposition deposition (FDM) and multi-jet printing (MJM). This method is based on the extrusion (extrusion) of consumables with the sequential formation of the finished product. As a rule, consumables consist of thermoplastics or composite materials based on them. nine0048

Melting, sintering or bonding

This approach is based on bonding powdered material together. Formation is done in different ways. The simplest is gluing, as is the case with 3D inkjet printing (3DP). Such printers deposit thin layers of powder onto the build platform, which are then selectively bonded with a binder. Powders can be made up of virtually any material that can be ground to a powder—plastic, wood, metal. nine0048

This model of James Bond's Aston Martin was successfully printed on Voxeljet's SLS printer and blown up just as successfully during the filming of Skyfall instead of the expensive original

sintering (SLS and DMLS) and smelting (SLM), which allow you to create all-metal parts. As with 3D inkjet printing, these devices apply thin layers of powder, but the material is not glued together, but sintered or melted using a laser. Laser sintering (SLS) is used to work with both plastic and metal powders, although metal pellets usually have a more fusible shell, and after printing they are additionally sintered in special ovens. DMLS is a variant of SLS installations with more powerful lasers that allow sintering metal powders directly without additives. SLM printers provide not just sintering of particles, but their complete melting, which allows you to create monolithic models that do not suffer from the relative fragility caused by the porosity of the structure. As a rule, printers for working with metal powders are equipped with vacuum working chambers, or they replace air with inert gases. Such a complication of the design is caused by the need to work with metals and alloys subject to oxidation - for example, with titanium. nine0048

Stereolithography

How an SLA printer works

Stereolithography printers use special liquid materials called "photopolymer resins". The term "photopolymerization" refers to the ability of a material to harden when exposed to light. As a rule, such materials react to ultraviolet irradiation.

Resin is poured into a special container with a movable platform, which is installed in a position near the surface of the liquid. The layer of resin covering the platform corresponds to one layer of the digital model. Then a thin layer of resin is processed by a laser beam, hardening at the points of contact. At the end of illumination, the platform together with the finished layer is immersed to the thickness of the next layer, and illumination is performed again. nine0048

Lamination

Laminating (LOM) 3D printers workflow

Some 3D printers build models using sheet materials - paper, foil, plastic film.

Layers of material are glued on top of each other and cut to the contours of the digital model using a laser or a blade.

These machines are well suited for prototyping and can use very cheap consumables, including regular office paper. However, the complexity and noise of these printers, coupled with the limitations of the models they produce, limit their popularity. nine0048

Fused Deposition Modeling (FDM) and Laser Stereolithography (SLA) are the most popular 3D printing methods used in the home and office.

Let's take a closer look at these technologies.

Fused Deposition Printing (FDM)

FDM is perhaps the simplest and most affordable 3D construction method, which makes it very popular.
High demand for FDM printers is driving device and consumable prices down rapidly, along with technology advances towards ease of use and improved reliability. nine0048

Consumables

ABS filament spool and finished model

FDM printers are designed to print with thermoplastics, which are usually supplied as thin filaments wound on spools. The range of "clean" plastics is very wide. One of the most popular materials is polylactide or "PLA plastic". This material is made from corn or sugar cane, which makes it non-toxic and environmentally friendly, but makes it relatively short-lived. ABS plastic, on the other hand, is very durable and wear-resistant, although it is susceptible to direct sunlight and can release small amounts of harmful fumes when heated. Many plastic items that we use on a daily basis are made from this material: housings for household appliances, plumbing fixtures, plastic cards, toys, etc. nine0048

In addition to PLA and ABS, printing is possible with nylon, polycarbonate, polyethylene and many other thermoplastics that are widely used in modern industry. More exotic materials are also possible, such as polyvinyl alcohol, known as "PVA plastic". This material dissolves in water, which makes it very useful for printing complex geometric patterns. But more on that below.

Model made from Laywoo-D3. Changing the extrusion temperature allows you to achieve different shades and simulate annual rings

It is not necessary to print with homogeneous plastics. It is also possible to use composite materials imitating wood, metals, stone. Such materials use all the same thermoplastics, but with impurities of non-plastic materials.

So, Laywoo-D3 consists partly of natural wood dust, which allows you to print "wooden" products, including furniture.

The material called BronzeFill is filled with real bronze, and models made from it can be ground and polished, achieving a high similarity to products made from pure bronze. nine0048

One has only to remember that thermoplastics serve as a binding element in composite materials - they determine the thresholds of strength, thermal stability and other physical and chemical properties of finished models.

Extruder

Extruder - FDM print head. Strictly speaking, this is not entirely true, because the head consists of several parts, of which only the feed mechanism is directly "extruder". However, by tradition, the term "extruder" is commonly used as a synonym for the entire print assembly. nine0048

FDM extruder general design

The extruder is designed for melting and applying thermoplastic thread. The first component is the thread feed mechanism, which consists of rollers and gears driven by an electric motor. The mechanism feeds the thread into a special heated metal tube with a small diameter nozzle, called a "hot end" or simply a "nozzle". The same mechanism is used to remove the thread if a change of material is needed. nine0048

The hot end is used to heat and melt the thread fed by the puller. As a rule, nozzles are made from brass or aluminum, although more heat-resistant, but also more expensive materials can be used. For printing with the most popular plastics, a brass nozzle is quite enough. The “nozzle” itself is attached to the end of the tube with a threaded connection and can be replaced with a new one in case of wear or if a change in diameter is necessary. The nozzle diameter determines the thickness of the molten filament and, as a result, affects the print resolution. The heating of the hot end is controlled by a thermistor. Temperature control is very important, because when the material is overheated, pyrolysis can occur, that is, the decomposition of plastic, which contributes both to the loss of the properties of the material itself and to clogging of the nozzle. nine0048

PrintBox3D One FDM Printer Extruder

To prevent the filament from melting too early, the top of the hot end is cooled by heatsinks and fans. This point is of great importance, since thermoplastics that pass the glass transition temperature significantly expand in volume and increase the friction of the material with the walls of the hot end. If the length of such a section is too long, the pulling mechanism may not have enough strength to push the thread. nine0048

The number of extruders may vary depending on the purpose of the 3D printer. The simplest options use a single print head. The dual extruder greatly expands the capabilities of the device, allowing you to print one model in two different colors, as well as using different materials. The last point is important when building complex models with overhanging structural elements: FDM printers cannot print “over the air”, since the applied layers require support. In the case of hinged elements, temporary support structures have to be printed, which are removed after printing is completed. The removal process is fraught with damage to the model itself and requires accuracy. In addition, if the model has a complex structure with internal cavities that are difficult to access, building conventional supports may not be practical due to the difficulty in removing excess material. nine0048

Finished model with PVA supports (white) before and after washing

In such cases, the same water-soluble polyvinyl alcohol (PVA) comes in handy. Using a dual extruder, you can build a model from waterproof thermoplastic using PVA to create supports.

After printing, PVA can be simply dissolved in water and a complex product of perfect quality can be obtained.

Some FDM printers can use three or even four extruders. nine0048

Working platform

Heated platform covered with removable glass work table

Models are built on a special platform, often equipped with heating elements. Preheating is required for a wide range of plastics, including the popular ABS, which are subject to a high degree of shrinkage when cooled. The rapid loss of volume by cold coats compared to freshly applied material can lead to model distortion or delamination. The heating of the platform makes it possible to significantly equalize the temperature gradient between the upper and lower layers. nine0048

Heating is not recommended for some materials. A typical example is PLA plastic, which requires a fairly long time to harden. Heating PLA can lead to deformation of the lower layers under the weight of the upper ones. When working with PLA, measures are usually taken not to heat up, but to cool the model. Such printers have characteristic open cases and additional fans blowing fresh layers of the model.

Calibration screw for work platform covered with blue masking tape

The platform needs to be calibrated before printing to ensure that the nozzle does not hit the applied layers and move too far causing air-to-air printing resulting in plastic vermicelli. The calibration process can be either manual or automatic. In manual mode, calibration is performed by positioning the nozzle at different points on the platform and adjusting the platform inclination using the support screws to achieve the optimal distance between the surface and the nozzle.

As a rule, platforms are equipped with an additional element - a removable table. This design simplifies the cleaning of the working surface and facilitates the removal of the finished model. Stages are made from various materials, including aluminum, acrylic, glass, etc. The choice of material for the manufacture of the stage depends on the presence of heating and consumables for which the printer is optimized.

For a better adhesion of the first layer of the model to the surface of the table, additional tools are often used, including polyimide film, glue and even hairspray! But the most popular tool is inexpensive, but effective masking tape. Some manufacturers make perforated tables that hold the model well but are difficult to clean. In general, the expediency of applying additional funds to the table depends on the consumable material and the material of the table itself. nine0048

Positioning mechanisms

Scheme of operation of positioning mechanisms

Of course, the print head must move relative to the working platform, and unlike conventional office printers, positioning must be carried out not in two, but in three planes, including height adjustment.

Positioning pattern may vary. The simplest and most common option involves mounting the print head on perpendicular guides driven by stepper motors and providing positioning along the X and Y axes. nine0048

Vertical positioning is carried out by moving the working platform.

On the other hand, it is possible to move the extruder in one plane and the platforms in two.

SeemeCNC ORION Delta Printer

One option that is gaining popularity is the delta coordinate system.

Such devices are called "delta robots" in the industry.

In delta printers, the print head is suspended on three manipulators, each of which moves along a vertical rail.

The synchronous symmetrical movement of the manipulators allows you to change the height of the extruder above the platform, and the asymmetric movement causes the head to move in the horizontal plane.

A variant of this system is the reverse delta design, where the extruder is fixed to the ceiling of the working chamber, and the platform moves on three support arms. nine0048

Delta printers have a cylindrical build area, and their design makes it easy to increase the height of the working area with minimal design changes by extending the rails.

In the end, everything depends on the decision of the designers, but the fundamental principle does not change.

Control

Typical Arduino-based controller with add-on modules

The operation of the FDM printer, including nozzle and platform temperature, filament feed rate, and stepper motors for positioning the extruder, is controlled by fairly simple electronic controllers. Most controllers are based on the Arduino platform, which has an open architecture. nine0048

The programming language used by the printers is called G-code (G-Code) and consists of a list of commands executed in turn by the 3D printer systems. G-code is compiled by programs called "slicers" - standard 3D printer software that combines some of the features of graphics editors with the ability to set print options through a graphical interface. The choice of slicer depends on the printer model. RepRap printers use open source slicers such as Skeinforge, Replicator G and Repetier-Host. Some companies make printers that require proprietary software. nine0048

Program code for printing is generated using slicers

As an example, we can mention Cube printers from 3D Systems. There are companies that offer proprietary software but allow third-party software, as is the case with the latest generation of MakerBot 3D printers.

Slicers are not intended for 3D design per se. This task is done with CAD editors and requires some 3D design skills. Although beginners should not despair: digital models of a wide variety of designs are offered on many sites, often even for free. Finally, some companies and individuals offer 3D design services for custom printing. nine0048

Finally, 3D printers can be used in conjunction with 3D scanners to automate the process of digitizing objects. Many of these devices are designed specifically to work with 3D printers. Notable examples include the 3D Systems Sense handheld scanner and the MakerBot Digitizer handheld desktop scanner.

MakerBot Replicator 5th Generation FDM Printer with built-in control module on the top of the frame

The user interface of a 3D printer can consist of a simple USB port for connecting to a personal computer. In such cases, the device is actually controlled by the slicer. nine0048

The disadvantage of this simplification is a rather high probability of printing failure when the computer freezes or slows down.

A more advanced option includes an internal memory or memory card interface to make the process standalone.

These models are equipped with control modules that allow you to adjust many print parameters (such as print speed or extrusion temperature). The module may include a small LCD display or even a mini-tablet. nine0048

Varieties of FDM printers

Professional Stratasys Fortus 360mc FDM printer that allows printing with nylon

FDM printers are very, very diverse, ranging from the simplest homemade RepRap printers to industrial installations capable of printing large-sized objects.

Stratasys, founded by Scott Crump, the inventor of FDM technology, is a leader in the production of industrial installations. nine0048

You can build the simplest FDM printers yourself. Such devices are called RepRap, where "Rep" indicates the possibility of "replication", that is, self-reproduction.

RepRap printers can be used to print custom built plastic parts.

Controller, rails, belts, motors and other components can be easily purchased separately.

Of course, assembling such a device on your own requires serious technical and even engineering skills. nine0048

Some manufacturers make it easy by selling DIY kits, but these kits still require a good understanding of the technology. RepRap Printers nine0048

And, despite their "homemade nature", RepRap printers are quite capable of producing models with quality at the level of expensive branded counterparts.

Ordinary users who do not want to delve into the intricacies of the process, but require only a convenient device for household use, can purchase a ready-made FDM printer.

Many companies are focusing on the development of the consumer market segment, offering 3D printers for sale that are ready to print “right out of the box” and do not require serious computer skills. nine0048

3D Systems Cube consumer 3D printer

The most famous example of a consumer 3D printer is the 3D Systems Cube.

While it doesn't boast a huge build area, ultra-fast print speeds, or superb build quality, it's easy to use, affordable, and safe: This printer has received the necessary certification to be used even by children.

Mankati FDM printer demonstration: http://youtu.be/51rypJIK4y0 nine0048

Laser Stereolithography (SLA)

Stereolithographic 3D printers are widely used in dental prosthetics

Stereolithographic printers are the second most popular and widespread after FDM printers.

These units deliver exceptional print quality.

The resolution of some SLA printers is measured in a matter of microns - it is not surprising that these devices quickly won the love of jewelers and dentists. nine0048

The software side of laser stereolithography is almost identical to FDM printing, so we will not repeat ourselves and will only touch on the distinctive features of the technology.

Lasers and projectors

Projector illumination of a photopolymer model using Kudo3D Titan DLP printer as an example

The cost of stereolithography printers is rapidly declining due to growing competition due to high demand and the use of new technologies that reduce the cost of construction. nine0048

Although the technology is generically referred to as "laser" stereolithography, most recent developments use UV LED projectors for the most part.

Projectors are cheaper and more reliable than lasers, do not require the use of delicate mirrors to deflect the laser beam, and have higher performance. The latter is explained by the fact that the contour of the whole layer is illuminated as a whole, and not sequentially, point by point, as is the case with laser options. This variant of the technology is called projection stereolithography, "DLP-SLA" or simply "DLP". However, both options are currently common - both laser and projector versions. nine0048

Cuvette and resin

Photopolymer resin is poured into a cuvette

A photopolymer resin that looks like epoxy is used as consumables for stereolithography printers. Resins can have a variety of characteristics, but they all share one key feature for 3D printing applications: these materials harden when exposed to ultraviolet light. Hence, in fact, the name "photopolymer".

When polymerized, resins can have a wide variety of physical characteristics. Some resins are like rubber, others are hard plastics like ABS. You can choose different colors and degrees of transparency. The main disadvantage of resins and SLA printing in general is the cost of consumables, which significantly exceeds the cost of thermoplastics. nine0048

On the other hand, stereolithography printers are mainly used by jewelers and dentists who do not need to build large parts but appreciate the savings from fast and accurate prototyping. Thus, SLA printers and consumables pay for themselves very quickly.

Example of a model printed on a laser stereolithographic 3D printer

Resin is poured into a cuvette, which can be equipped with a lowering platform. In this case, the printer uses a leveling device to flatten the thin layer of resin covering the platform just prior to irradiation. As the model is being made, the platform, together with the finished layers, is “embedded” in the resin. Upon completion of printing, the model is removed from the cuvette, treated with a special solution to remove liquid resin residues and placed in an ultraviolet oven, where the final illumination of the model is performed. nine0048

Some SLA and DLP printers work in an "inverted" scheme: the model is not immersed in the consumable, but "pulled" out of it, while the laser or projector is placed under the cuvette, and not above it. This approach eliminates the need to level the surface after each exposure, but requires the use of a cuvette made of a material transparent to ultraviolet light, such as quartz glass.

The accuracy of stereolithographic printers is extremely high. For comparison, the standard for vertical resolution for FDM printers is considered to be 100 microns, and some variants of SLA printers allow you to apply layers as thin as 15 microns. But this is not the limit. The problem, rather, is not so much in the accuracy of lasers, but in the speed of the process: the higher the resolution, the lower the print speed. The use of digital projectors allows you to significantly speed up the process, because each layer is illuminated entirely. As a result, some DLP printer manufacturers claim to be able to print with a vertical resolution of one micron! nine0048

Video from CES 2013 showing Formlabs Form1 stereolithography 3D printer in action: http://youtu.be/IjaUasw64VE

Stereolithography Printer Options

Formlabs Form1 Desktop Stereolithography Printer

As with FDM printers, SLA printers come in a wide range in terms of size, features and cost. Professional installations can cost tens if not hundreds of thousands of dollars and weigh a couple of tons, but the rapid development of desktop SLA and DLP printers is gradually reducing the cost of equipment without compromising print quality. nine0048

Models such as the Titan 1 promise to make stereolithographic 3D printing affordable for small businesses and even home use at around $1,000. Formlabs' Form 1 is available now for a factory selling price of $3,299.

The developer of the DLP printer Peachy generally intends to overcome the lower price barrier of $100.

At the same time, the cost of photopolymer resins remains quite high, although the average price has fallen from $150 to $50 per liter over the past couple of years. nine0048

Of course, the growing demand for stereolithographic printers will stimulate the growth in the production of consumables, which will lead to further price reductions.

Go to the main page of the Encyclopedia of 3D printing

3D Printing Basics / Habr

KolianM

July 19, 2018 at 12:49 pm

Working with 3D graphics *Prototyping *DIY or DIY 3D printers

casting or milling. This is due to the technical features of the 3D printer, from which you need to either squeeze the maximum benefit, or adjust to the disadvantages of printing. nine0048

As a caveat, I note that these recommendations relate mainly to the FDM (FFF) 3D printing method, in which a plastic rod is heated by a moving extruder that forms the part layer by layer.

3D model development starts with a sketch. It can be a drawing on paper, a material prototype, a mental image, etc. What is important to pay attention to when creating such a sketch and the model itself, we will analyze in detail.

Part strength

Here and further down the text there are several sub-points that must be taken into account at the same time, kept in mind from the very beginning. nine0048

Be aware of the layering or anisotropy of the material: it is much easier to break a part in layers than across. This must be taken into account in advance, given the location of the 3D model on the 3D printer table.
Add fillets. The leg of the stool and the tabletop at the junction should have a rounded corner. At the same time, the larger the radius of curvature, the stronger the leg will be fixed on the tabletop. Similarly for various body parts. Modeling a box All right angles are rounded. It doesn't matter what plane they are in. Even where a right angle is needed, we make a radius of 0.5 mm. The printer will pass through such a section more easily than an unrounded one, there will be no impact from a sharp stop of the extruder, the part will not sway, and other pluses. nine0044
Wall thickness and filling. The maximum strength at 100% infill is a fact, but if you need to lighten the part or save plastic, you can make a much larger wall thickness in the print settings, while setting the infill much lower. This works with parts that have holes for fasteners. When creating machine code for a printer, absolutely all the outer walls are thick, so the fastener will be surrounded by a reliable thick layer of plastic of your part.
Support. This element affects the strength in that the layers supported by the support are not always ideal in structure. This can be solved by increasing the wall thickness, filling, but it is better not to do support at all. Support is added by the slicer depending on the angle between the part wall and the table plane. Often the default is 60 degrees, sometimes 45. This setting is selected experimentally for each 3D printer. You can check this with the help of special test parts. For example, https://www.thingiverse.com/thing:2806295 - do not forget to turn off support to check the real quality of 3D printing in its absence. For example, you need to print a T-piece for tubes. Cast products are made in a T-shape. 3D printing makes the product L or even Λ-shaped. In the second case, support can even be avoided, and the part will be stronger due to the layers located at an angle of 45 degrees to the tubes. We, in the workshop, set up slicers for each machine and ask the client about the strength requirements, and, depending on this, choose a 3D printer to print. nine0044

Geometric restrictions

The wall thickness is limited from below by the size of the 3D printer nozzle. Its diameter is constant and in the vast majority of cases it is 0.4 mm. Smaller thickness - long 3D printing for most parts. The larger the nozzle, the bonds between the layers are less strong, the steps between the layers are more visible. And in general, the wall thickness should be a multiple of 0.4 mm, then the 3D printer will be able to accurately make the wall in two passes (0.8 mm), in 3 passes (1.2 mm), etc. Other thicknesses will cause the 3D printer to leave a gap or overflow, which negatively affects the strength and appearance of the printed part. nine0044
3D printing of thin cylinders and "needles". For 3D printing of such products, special 3D printer settings are needed: low 3D printing speed, allow time for cooling, otherwise such a structure will bend. Vertically standing thin elements are best avoided at all costs. Even if they are printed, they will be very fragile. It makes sense to leave them only for decorative purposes, but you must be prepared that their quality will be worse than the quality of other elements of the 3D part.
3D printed holes. I note that if the hole is straight and through, then it can be drilled, if it is curved and requires support, then it may turn out that it will be impossible to get support.
When 3D modeling, it is important to consider the overall dimensions of the 3D printer. We use convenient 3D printers, table 250x250 mm, diagonal 353 mm. This is where you need to enter the dimensions, if possible. Otherwise, you need to order either an industrial 3D printer with a large print area, or use gluing, but assembly is better, so the assembly process will be controlled by the developer, and not by the 3D printing master. nine0044
Large footprint may cause edges to peel off the table. We use special glue, but this does not always help. We are periodically approached with a complaint about colleagues in the shop that for them such “minor” defects as a folded edge are not a reason to restart 3D printing, take it as it is. But an engineer who 3D models a part can take this into account in his work and make either assemblies or thin-walled flat 3D parts that “do not have enough strength” to compress the outer contour and, as a result, raise the edge. nine0044
Tall and thin "towers" may not work well due to vibrations that occur when the 3D printer is running closer to the top, layer shifts are also possible.

Dimensional stability, accuracy

Precise 3D printing is quite rare. I don’t want to speak in engineering terms here, but the likelihood that a complex composite structure will assemble the first time is very low. Here, rather, you need to take into account the fact that you can then mechanically refine the details. nine0044
Holes for fasteners are best done with a margin of 0.5 mm in diameter. This will not reduce strength, the fasteners will also not dangle due to tightening forces, but if you do it without a margin, you will definitely have to drill it out. Reducing the size of a large shaft, >10mm sandpaper is much easier than making a hole, which requires a huge drill that cuts into the plastic walls and breaks the part, or gets stuck in it. It is also important to consider that when drilling, the plastic melts and the drill can melt into it so that it cannot be removed. There have been cases. nine0044
Heat shrinkage is not always compensated, more precisely, it is very difficult to catch it, it is not the same in different directions, so it is extremely difficult to take it into account. It's easier to print a test version, and then make adjustments.

When looks matter

Think about how the craftsman will orient the part on the 3D printer table. 3D printing proceeds in layers, which is clearly manifested when printing surfaces that are at a small angle from the horizontal of the table. Skinning will be long and painful, because you will have to cut this "ladder" to the deepest depressions of the "steps". It is better to place such surfaces either horizontally, for example, put on a table, or increase the angle. In some cases, even adding support that spoils the wrong side of the wrong side saves time and effort on post-processing. nine0044
Support. First, the surface it supports has significantly more defects than without it. Secondly, thin and high support is weak, wobbly, which leads to the fact that the supporting part may have serious defects, or not work at all.
First layer quality improvement. You need to add a bevel. Even where a sharp corner is not needed, I recommend adding a chamfer of 0.5 mm. It will not be clearly visible, but the edge will be neat. nine0044

What you need to know in order not to make a mistake when ordering 3D printing

When appearance is important

Location of the part on the table. Remember about anisotropy.
Wall thickness and filling. What you can run into here: the filling is 20% cells, which are either visible through a thin outer wall, or the filling slightly tightens the outer wall during shrinkage, but at the same time it is visually easy to determine that there is support inside. Here, first of all, an increase in the thickness of the outer wall, or an increase in the filling density, helps. Please take this into account when ordering. nine0044

Postprocessing

The elimination of stepping is achieved by mechanical and chemical methods. It is possible to use putty. Acrylic paint available. If the part has a complex color structure, then we use the ProJet 4500 printer, which works on a different technology. He glues the powder particles together with colored ink glue. It turns out well.

Morality

In conclusion, I would like to note that these recommendations and the accumulated experience will make it possible to produce parts by 3D printing, which in their properties will not be inferior to cast ones, which makes it possible to save significant funds in the presence of a customized printer and small production volumes.