PS: there is also an obj format, printers basically support such format, but it is used rarely because STL is still the mainstream.

As for how a modeling for 3D printing is realized, I believe that it is essentially about how to acquire STL file. Of course, there are many methods, and I have classified them into the following according to different purposes:

1. CAD Design (Parametric Modeling)
It mainly aims at the application of mechanical components requiring parametric modeling design, common 3D CAD software can be competent, I have learned UG in my university and hence I usually use it, while my colleagues use Solidworks, Pro-E, Catia and so forth. These above are “professional” relatively, but some simple ones can be used as well, such as Sketchup of Google. In addition, there is another real “parametric” modeling design software suitable for those with competence in programming: OpenScad, which is open-source software and directly generates a model through code editing. Its disadvantage is less convenient than graphical modeling software (such as Solidworks, UG, etc.), but as for its advantage, scad file generated is small and its code can be called by other applications for modeling component databases, so they are used conveniently. Even though I can not program it well, I am interested in the software. As for this kind of software, I recommend Solidworks, you can also study Openscad if you are interest in it. I have just printed a six-cylinder engine block model today, which is just this kind of model as follows and realized by Ford Motor Company:

2. CG Modeling
3D max and maya that you mentioned are applicable; there are also Rhino and Blender, as well as simple ones such as Zbrush. I have ever used Blender, which is free open-source modeling software, but only the most essential functions of this software are used. Any model designed by this software requires being transferred into printable STL file, but which can cause many structural errors and hence require being processed, fortunately there are some software such as Meshmixer, Meshlab, netfab and so on, which can be used for restoration. I usually use Meshmixer, because it has rich functions and is specially used for 3D printed model processing for free. The following high quality corpse hunter head portrait is just designed by such software.

3. Amateurish Software
As for amateurish software, it is just a joke, this kind of software can meet basic requirements for common 3D modeling, they have good functions but insufficiently comprehensive in comparison with professional software such as Solidworks, maya and so on. A series of 3D design software (e.g., Tinkercad) derived from Autodesk (excluding Autocad) are simple very much, namely, Boolean operation is adopted for some entities to obtain simple printable models. Additionally, Meshmixer mentioned above can be used for mixing and matching of some models so as to spoof models. For example, the following one is model of Yoda mixed and matched with the figure of Buddha:
PS: You can browse the home page of Autodesk, where it seems that they are playing chess vigorously in the field of 3D printing software, Meshmixer has just been purchased by Autodesk, which can provide any free applicable modeling software easily used for us.

4. Portrait DIY Application
123 Dcatch protroduced by Autodesk can synthesize a printable 3D model with 20 pictures with different camera angles. Yesterday, I found the foreign Faceshop software by chance, it is one rechargeable software and your can use it for free within 15 days, and then you can adopt a picture and select the face profile to generate a 3D head portrait model. But the basic model of the head portrait is designed on the basis of the occidental. I tried it with my head image yesterday to finally generate a model with higher nose. Kinect is combined with Rconstructme software to directly scan a portrait, which probably lasts for more than 10 min, with a printed effect picture as follows:

There is good open-source 3D slice printing software Cura, which has the function that import bmp, jpg, png images to generate a model with Buddha statue effect. Currently, there are 3D originality printing shops at home, which can provide such printing service, with printed effect picture as follows:

5. Downloading Models Designed from Model Websites
At present, the best 3D printing model sharing website all over the world is Thingiverse – Digital Designs for Physical Objects, which is a model sharing website of Makerbot (it has been purchased by stratasys), with total models more than 600000 (codes)。Another one is https://www.youmagine.com protruded by Ultimaker of Cura, on which there are less models. They are two major foreign 3D printing model sharing websites with opposite styles, Makerbot emphasizes from open source to close source, but Ultimaker insists on the open source. Some other ones, such as 3D warehouse of Google, are available, not aiming at 3D printing. There is a perfect website in the U.K., that is Myminifactory：MyMiniFactory.com. We can not only directly purchase models from it, but also download STL for free from it. We are designing a model sharing website 523DP – Sharing 3D Printing Pleasure, which is under the development now, here the quantity of models is the largest at home and you can download models for free.
Learning Suggestions:
In my own opinions, the first (CAD modeling, recommended Solidworks) and second (CG design software, recommended 3dmax) categories are useful for ever, you can select any software for learning, then you will acquire a lot. If you would like them, you’d better learn both of them. Additionally, since you enjoy programming, I will recommend you to learn Openscad, which is simple and easily mastered. The difficulty is possibly dependent on software itself but languages, because the software has not been translated into Chinese and is not so convenient during use.

Knowledge Preparation

3D printing is a process of continuous adding, the layering of raw materials under computer control. There are a number of technologies as below:
1. Taken high polymer reaction as basic principle (SLA, Polymer Printing, Polymer Jetting, Digital Lighting Processing, Micro Stereolithography).
2. Taken sintering and melting as basic principle (SLS, SLM, EBM).
3. Taken powder-binder as basic principle (3DP, Zcorp, voxeljet).
4. Fuse deposition modeling technology (FDM).
5. Layer lamination manufacturing technology (LLM).
6. Aerosolprinting technology (Aerosolprinting).
7. Bioplotter technology (Bioplotter).
Each adding manufacturing technology possesses dissimilar principles. Yet, at the core, all aim to produce a layer based on computer data, and then produce one more layer upon the existing layer, and so on, until the entire three-dimensional model is established.

How to select a home-use 3D printer

The key factor in selecting 3D printer is stability and convenient use.
It is only for your own use, it is suggested not to consider color printing. It is not reliable. Color effects of low price printer are very poor. Layer thickness precision supported is similar. There is not much difference.

In aspects of mechanical precision, it is suggested to purchase those that look stable. If you have strong operational skills, you can purchase aluminum frame kit and assemble on your own.

As a beginner, you don’t have to consider what parameters are important. Select one that is already assembled, and at best, brand one with good comments, certain reputation, and some after-sales supporting. This can avoid many of the problems in future use, and get you experience the fun of successful printing. Interest can be kept on, and skills can then be deepened. I suggest that you can consider FlashForge, which has relatively high cost performance and four and half star favorable reception on Amazon.

Amazon.com: FlashForge 3d Printer, Dual Extruder, Both ABS and PLA Compatible, 8.8″x5.7″x5.9″build Volume, W/2 Free Rolls: Industrial & Scientific

How to set a model

At present, regardless of what kind of 3D printing, STL format file is usually applied. STL file, to put it simply, is a file format with triangle representing substance. This format is defined by the person who first invented 3D printing, and has now became default industry standard in the field of image processing. Today, there is a bunch of people who are trying to promote a 3D printing file with AMF format, which mainly adds information on model material, texture, color, etc. Perhaps in future, as technology progresses, color printing will become the mainstream, and this file format may gradually substitute STL. However, at the moment, STL format file is still the mainstream. As well, most printers support obj format files, though not often. Hence, STL is the mainstream.

Modeling software includes 3D max, AutoCAD, Solidworks, Pro-E, Catia, etc. It may be hard for you to use PROE, 3DMAX, MAYA, which are highly professional. It is recommended to start from Sketchup released by GOOGLE. It is considered entry-level 3D modeling software. And also, Rhino, Blender, and Zbrush which is simpler. I’ve used Blender. It is an open source modeling software, for free. I only used its basic functions. Models designed by this type of software needs to be converted into printable STL file. There may be some structural errors to be handled with. And the frequent software for modification are Meshmixer, Meshlab, netfab. I mostly useMeshmixer. It possesses rich functions, and is free of charge. And it is specifically applied for 3D printing model processing.

Nevertheless, as a beginner, you can find ready-made models, e.g. model community (Thingiverse), where there are a lot of beautiful Baymax models.

Select printing material

There are several categories: plastic, metal, ceramics, sugar, sand, etc.

Frequently used plastic materials: ABS, PLA, nylon, photosensitive resin, rubber.

Frequently used metal: stainless steel, titanium, aluminum, and various alloys.

Desktop 3D printer consumables, mainly include three, ABS (Acrylonitrile Butadiene Styrene), PLA (Poly Lactic Acid) and PVA (Polyvinyl alcohol). ABS is the cheapest, with melting point in between 215 ℃ and 250 ℃. PLA is more environmentally friendly, and with lower melting point. Given that desktop 3D printer has patent restrictions, and often has to use open print cartridge design, print compartment temperature is difficult to ensure. Therefore, it is more appropriate to use PLA. PVA is usually used for printing support portion.

As for printing supplied, PLA is recommended for self use, which has no smell. And this one on AMAZON is recommended.

Argos 1.75mm PLA (Clear)(Natural) MADE IN THE USA : 3D Printer Filament – 1kg (2.2lbs) Spool – Dimensional Accuracy: +/- 0.05mm

Start Production

1. Design Production:
use modeling software to create CAD models and ultimately export STL files. If you downloaded the existing model, you can skip this step.

2. Slicing:
Import STL file generated into printer supporting software, obtain files after slicing. Then, import file into printer printing program. (Basically, all FDM printers have the same step like this.)

3. Printing Phase:
Printer starts to print. It takes some time, and perhaps for a night.

4. Post Processing:
Pose processing is conducted based on the different printing materials. (In general, FDM machines require manual removal of supporting. Advanced FDM machines depend on water-soluble means to remove supporting.)

Achievements Appreciation

Front of Baymax

Back of Baymax

Baymax in Helmet

Baymax in Helmet 2

Baymax in Helmet 3

Baymax in Helmet 4

Helmet

(Author:前端农民工 Source:zhihu.com, ofoct.com translate to English version)

In fact, although there are numerous brands of 3D printer, the working principle is the same in nature. What is the working principle then? Let’s first have a look at the traditional ink jet printer that prints on paper.


Figure Paper Printer

As we all know, what paper printer prints is planar image. Digital image is a pure color “pixel” piecing together after amplification. Each coordinate point marks one color value for storage.

Figure Pixel For those with intensity phobia, please quickly turn to the next page.

In other words, if we have a “spray-head”, that can freely move on one plane, pixels are injected from on the coordinate system, then printing work is done.

Figure Plane Rectangular Coordinate System

Therefore, this appears. To help you understand, I made some simplification when setting the model.

Figure Ink Jet Printer Simple Working Principle

First, what we need most is the spray head. It sprays out “pixel” one by one. Now, let’s take a look at what is a spray head.

Figure Ink Jet Printer Spray Head

Paper can be brought down by a roller, which completes Y axis movement. The little spray head in the middle moves horizontally, and completes X axis movement. In this way, a plane picture is printed out.
Yet, how does the little spray head in the middle move?

Figure Synchronization Belt (Toothed Belt)

Yes, this with a scientific name of synchronization belt is what we commly called toothed belt. Once it is matched with toothed gear, it can perform free transmission. Sensitive equipment, such as printer, requires toothed belt as transmission device, in general.
Some people say, why are you talking too much nonsense? I only want to hear about 3D printing. Just wait a second. Let’s see. The carrier of plane printing is paper. Plane printing use “paint” to spray. If we are to print something three-dimensional, actual materials must be used in 3D printing.

Here, comes the magic key.

Figure General 3D printing generally use “strands”

In other words, what we normally see in 3D printer, printing material changes from ink to “thermoplastic plastics”. What is thermoplastic plastic? Thermoplastic becomes soft once heated, and turn to its original form when cooled down. The most commonly used 3D printing materials are ABS and PLA. ABS is an extremely common synthetic plastic. Its nature is A (acrylonitrile), B (butadiene), S (styrene). Just forget it. PLA is also called polylactic acid. Its melting point is very low. Basically, fusion processing can be conducted at 185°C. Therefore, it is the most commonly seen printing material. But, why is this material similar to woolen yarn wire rod?　In fact, it’s simple. If you place plastics (granules) in flaming spray head, in less than two minutes, the spray head will be blocked. Only wire rod can be “steady”.

As we have the material, now we only lack carrier. Let’s add a small steel plate.

Figure When setting the model, I added a small steel plate as shown in above figure. Small steel plate cannot be transmitted in the way like paper by roller. Hence, we add a “synchronization belt” under the small steel plate, to conduct Y axis transmission.
Now the platform is set. X axis and Y axis can move freely. Small spray head can freely move to any position on the small steel plate.

Only one factor is lacking in three-dimensional printing, the Z axis.

Figure Space Rectangular Coordinate System

Figure Here comes Z axis, the spiral thick stick in above figure.

On the spray head arrangement that can move on X axis, we can add a “magic key” in mechanics. That is “threadlike thick stick”.

We can comprehend threadlike thick stick as a big screw. A nut connects a threadlike thick stick. Once the threadlike thick stick is driven by the electric motor to spin, the spray head can move up and down freely.

The spray head is no longer a common spray head. It can move freely space. Let’s have a look at the effects figure.

Figure This is the equipment that we combined. (For better looking purpose, I used orange color.)

This is the fundamental transmission structure for 3D printer. It is not complicated. In nature, it is just a spray head that can move freely in three axes.
Okay. Let us now load the bullet (raw material), and see how it works.

Figure Loaded 3D Printer

We found that 3D printing, in nature, is to melt thermoplastics, spray out thinner “thread” by spray head, and layer by layer, spraying continue, and the layers overlay. Essentially, 3D printing is merely a combination of “plane” layer by layer, which in turn, form a three-dimensional thing.

Figure Use software to simulate 3D printing principle.

Figure These are some of the articles printed by low precision 3D printer. We can easily distinguish the layers and supporting lines one by one. Under most circumstance, such precision is sufficient.

As we all know, to print a plane picture, a JPG picture is enough. Then, in 3D printing, what kind of “doc” do we use for printing?

Figure In fact, the metal glowing printer that you just see, is applied by this thing.

This is common software used in industrial design and architecture – rhino. Also, solidworks is a common modeling software for parts manufacturing and assembly. There two are more or less inclined to engineering course. 3DMAX and Maya, as you are all familiar with, are modeling software that possess more artistic usage. The modeling principle of these software are not entirely the same. At core, it’s all planes form three dimensions. All “three dimensions” in the world are “piled” by planes in nature. Therefore, the working mode of modeling software is likewise. Almost all modeling software around the world has one most fundamental command, that is, extrusion.

Figure The extrusion process of using one plane to stretch on Y axis.

Figure More complex solidworks assembly parts.

Figure This is a monkey that I made. I wish I have the time to print it out.
Before applying colors, the monkey is like this.

Figure The monkey before applying color.

Hence, to complete a 3D print work, modeling is the first step. As I’m not an art major, my modeling skills cannot match those animation master, I am okay in modeling some industrial parts and product shells.

Regardless of Rhino 3DM format, 3DMAX max format, or DirectX etc., we all can save our software in STL mode, which is applicable to 3D printing.

Okay. The next step is to import SLT mode file into drive software, and then we can start printing.

Figure PLA printing low precision 3D printing drive software. We can see the various parameters in printing. And as I said at the very beginning, we can use the round panel above to debug the movements of X, Y, Z axes, and use the button below to control temperature.

Figure The printing begins.

Actually, this is how it looks at completion. We can use this physical figure to see the inside of 3D printer, which is similar to my model setting figure at the beginning with more disordered wires.

Okay. The above is the fundamental low precision 3D printer working principle and work flow.

No rush. It’s not done. Let’s have a look at high precision 3D printer in other models in the world.

As we all know, for today’s plane printer, in addition to ink jet printer, there are laser printer, electrostatic printer, etc.. 3D printer, as well, adopts the same working principle as I described before, though its name is a bit glamorous.

Let’s now talk about plane printer first.

Take plane laser printer as an example. In nature, it transmits beam “image” to static “image” via toner cartridges, selectively “solidify” a whole piece of powdered ink, and prints it on paper.

It’s okay not to ponder on this. To put it in a simple way, one is a prayer free move for ink solidification, and the other is laser static selectively solidifies in the sea of ink powder.

Therefore, besides layered thermoplastics 3D printer discussed above, there is another high precision 3D printer with similar principle with plane laser printer.

The other name for such printer is SLA.

Actually, there is a friend of thermoplastics discussed before, called “thermosetting plastic”. In normal condition, this kind of plastic may possibly be liquid. Once heated or under strong light, or with catalyst function, it will solidify. Such plastic then can no longer be re-utilized for thermoplastic. In other words, it keeps one form for a lifetime.

Figure SLA 3D Printer

As we can see, this kind of printer selectively solidify thermoplastic “sea” via laser beam, and conducts higher precision printing. In nature, it working principle is still first X, Y plane formation and then Z axis layer by layer printing mode.

Of course, there is another SLS (Selective Laser Sintering) 3D printer that possesses similar working principle with this printer. The printing mode of SLS is called – selective laser sintering.

Figure Selective Laser Sinter Technology

This is a kind of high precision 3D printing. It changes liquid above to power material. Via laser, powder sea is selectively melted. In fact, it’s a bit similar to plane laser printer. In nature, 3D formation stays the same with the mode described above. SLS printing mode can already be applied in metal 3D printing. It is a significant progress in 3D printing.

Figure Metal pistols printed with adoption of selective laser sintering technology

Okay, let’s display the works of high precision 3D printer that we talked before.

Figure AGILISA, a pretty good high precision 3D printer in Japan.

Figure The internal structure of this printer. It can be observed that all transmission devices are of better precision.

Figure Solidworks parts printed by high precision 3D printer. Spring printed with this material is elastic. And such precision is able to handle some medical devices.

Figure High Precision Model

As a matter of fact, for 3D printing, a saying goes like this – idea in the 10th century, basic technology in 20th century, and market in 21st century.

In today’s world where industrial design is gradually progressing and industrial design is developing speedily, 3D printing possesses immeasurable space for complex formation scale production, individualized customization, and macromolecule material processing. In the 21st century, 3D printing will keep on rapid development. With the efforts of generations of designers and manufacturers, I believe, 3D printing can truly and thoroughly change the world.

(Author:安森垚 Source:zhihu.com, ofoct.com translate to English version)