Sunday, October 22, 2017

Introduction to 3D CAD *

* An update to my popular post from 2014
Just looking for free 3D CAD software? You can scroll down to " Hobby - Free software for makers"
The first rule for printing in 3D is the presence of a 3D file.

The next article will lead you through basics computer-aided design (CAD) terms, will review the market players and will guide you to best options to start design for free with a robust 3D CAD.

There is one common principle today for all 3D production machines, from a 150 $ self-assembled home printer to a million dollars machine that prints medical and aerospace titanium parts, all of which receive the printing instructions from a program that prepares a 3D STL file . A software than slices the STL file into layers and converts the two-dimensional mask created in each layer into instructions for the 3D printer. For a successful print, the printer software must have a 3D file that accurately describes the body and its details. Currently, all software that sends instructions to the printing machine can work with at least one standard file called STL that contains a collection of 3D polygons that description the 3D objects. There are dozens of software for creating 3D objects using SOLID, surfaces or Mesh technology and each one of them can export STL file.

The 3D software can be divided into three groups. At the top are the expensive High-End software. In the middle are the mainstream software that are common in design offices and universities, and there is also the group of software for amateur and makers, which of course are also the cheapest. In the following list I will briefly review some of the popular modeling software for "small" objects (as opposed to civil engineering and architecture programs), with an emphasis on the most suitable for beginners.

Before we proceed, we will become acquainted briefly with a number of technical terms that are important for the continuation:

Basics terms:

    Solid - The term solid is not just the name for some popular software. Solid technology allows to design precise and details 3D bodies while providing physical properties to the computerized model that brings it very close to reality. "Solid parametric" indicates that the software allows changing the 3D model by changing predefined parameters such as dimensions. The solid Parametric software is the masters in the world of mechanical engineering.

    Mesh - A three-dimensional model consisting of a network or a collection of lines forming three-dimensional polygons that represent the 3D model. The Mesh model is less accurate, cannot be modified by parameters and is more suitable for creating complex organic shapes and free-form design body. Common mesh files extensions are STL or OBJ and sometimes VRML.

    Direct Editing - A term associated with solid software and describes the ability to easily modify and reconstruct 3D objects without relying on the original parameters. Direct editing is considered a technique that is more suitable for beginners and casual users.

    Parametric - A 3D parametric model is controlled by dimensions or constraints in a way that changing a value will change the model geometry. Parametric model can capture the design intents; control the relationships between features and parts in assembly, create associative drawings and maintain a virtual prototype.

    Surface - While solid describes the entire body, surface software only deals with external topology. The "surface" capabilities enable the creation of more complex geometries while maintaining a smooth, flowing appearance. The automotive industry uses surface software to shape the curved surfaces in the vehicle. Surface technology is also popular for art and industrial design and to design organic shapes for medical and healthcare devices. 

    Software Classification: 

1. High End
2. Main Stream
3. Hobby

    High-End Software 

    Are very common in the automotive and aviation industries and provides a comprehensive solution that includes many specific applications and powerful tools for managing large assemblies with tens of thousands of parts. The high-end software are very expensive and takes a lot of time and experience to specialize.

    The three best known High-End Software are:
    • PTC Creo (Pro/E) – World first solid parametric software. 
    • Siemens NX – A comprehensive software package widely used in the automotive and aviation industry
    • Catia by Dassault Systèmes - A comprehensive software package widely used in the automotive and aviation industry
    Autodesk Alias  is another High-end software just for surfaces design. It is common among industrial designers and car designers. Difficult to learn and use but packed with fantastic abilities. If you fantasize about being a car designer, this is the software for you

    2. Main Stream software  

    The most common software for solid parametric design, relatively easy to learn and use. Widely used in engineering and design institutions.

    The most popular:
  • SolidWorks (Dassault Systèmes ) – World most popular solid software. Started at 1996 as the first native window 3D software. Relatively easy to use and learn.
  • Autodesk Inventor – A good alternative to SolidWorks with advanced tools for free-form design 
  • Solid Edge (Siemens NX) – The first software to combine direct editing with parametric design

The different:

    SpaceClaim (Ansys) - direct editing solid software very suitable for use in 3D printing. Unskilled users will find it easy and fast to use and with ability to edit STL files, making it important tool for preparing model to 3D printing

    The new generation:

    OnShape – The first 100% cloud solid software. No installation or dependency on your OS, run on mobile device, tablet or Mac. Easy to use and very modest in hardware resources. OnShape is the best entry tool for the world of design in Solid and is an excellent learning tool for those who wish to continue their professional programs. If you keep your design public, you can try it for free. 

    Autodesk Fusion 360 - Autodesk is constantly pushing new capabilities to the Fusion 360 cloud computing platform. The software includes endless capabilities for design, simulation, and manufacturing. The software requires local installation and uses the cloud as a computational power to perform complex operations more quickly and the cost is very 
    Autodesk Fusion 360

Not Solid, hard to use but popular:

Autodesk 3D MAX - Mesh/polygon software. Highly versatile and widely used software for animation purposes. The MAX is not engineering software and is not as easy to use as the solid software. But, it is the only one in the group that allows modeling of characters, animals, and other strange forms. 

Rhino – A 3D Surface software. Most popular for jewelry design and complex organics shapes.

3. Hobby - Free software for makers:

Programs that provide good 3D capabilities at zero cost. Some of those free software includes surprising capabilities that are not available in the expensive Mainstream software. 
Please note that the world of CAD is divided into a number of categories and 3D technologies. In general, Solid software is for mechanical design, Mesh software belongs to the world of animation and organic shapes. With Solid technology, organic shapes can be an impossible task even for an experienced user. 
DesignSpark Mechanical 

The next two software have surprising tools and capabilities that can work for an experienced user. Those who are new to the technology will get a great opportunity to learn the basics. They come from leading commercial companies and can be downloaded and used for free without restrictions. Just note, the solid software can eat all your computer resources. Without a powerful processor and enough RAM, the experience can be frustrating. 

DesignSpark Mechanical - A "naked" version of the SpaceClaim software branded by RS, a hardware manufacturer. Surprising capabilities and good performance with powerful direct editing software. You can import STEP files and save files to STL for 3D printing. The software continues to be updated and includes the ability to edit and use STL files for further building in Solid, unique capabilities that are hard to found in other software. 

PTC Creo Elements PTC is the inventor of the parametric solid. Several years ago, it acquired HP's CoCreate software to access the direct editing capabilities that HP software hade for years. Elements / direct is a great design software, rich in tools and capabilities and can be downloaded and used for free without time limit. The software is limited to 60 parts in one assembly, more than enough for the amateur designer. 

Autodesk 123D Design Until recently, Autodesk was the only company that took seriously the world of Makers and 3D printing with a collection of 3D (and 2D) software designed for the casual user. Recently, the company retires some of the free projects in the 123D software family and it is not available in Autodesk web site anymore. 
Rush and download the software from the alternative link above as long as it is available. 

Few more option to consider:

TinkerCAD - Cloud software and a very easy to use one. It uses unique technology, enables the editing of STL files, and most suitable for old PCs. TinkerCAD is an important tool in the toolbox of any home enthusiast who wants to design STL files. 

FreeCAD - Open source Solid software. Provides tools to convert file formats and the possibility to work with Mesh files. As a design tool, it can not compete with the other programs mentioned here. FreeCAD has great potential but is unstable and not easy to use 

SketchUP - Popular software with a large user base. Very easy to use, designed primarily for the architectural 3D design. It's very easy to get results with the software for simple projects 
Blender - Powerful animation software. The free equivalent to 3D Max. Using a blender can be frustrating. There are countless examples of amazing models made on the web, but the software requires learning and knowledge. It is difficult to operate and is suitable mainly for those who intend to specialize in the field of animation. If you wish to design dragons and monsters Blender may be exactly the software for you.

Remember, 3D CAD should be fun. If it is not, just try other software

Pedro's Tulio QR Multi-Tool

Gal Raz

Tuesday, August 30, 2016

A four steps guide for a successful 3D project

The next article published first at  magazine

Printed Glasses frames in Aluminum (top) and Titanium
My first 3D printed project was a little bit disappointing. My new innovation looked rough and weak and the 3D model was not functioning well. Obviously, in 2006 we had fewer options for a 3D printed prototype but, the path was similar to what we have today. Therefore, my first experience was very similar to what I saw over the years with many customers and thousands of projects. For first impression, the 3D printed parts looks stunning. It is such a great feeling to see your design come to life in a real 3D model but, when you go into details, something is always missing. The materials, the details, the color or even the mechanical properties are not there.
In order to help you to succeed from the first 3D printed project, I’m posting those simple rules based on my experiences with more then million 3D printed parts in more than 7 different printing technologies and different materials.

  1. Know your 3D CAD software

Popular Solid modeling Software
Popular NON Solid Software

We can’t print in 3D without a 3D CAD model. Also, the print results relay on the suitability of the 3D file and the 3D printing method we intend to use. The standard file we use in 3D printing is the STL file format. Almost all the 3D software can export to STL format but, not all at the same quality.
When it comes to 3D printing, there are two groups of software, 3D Solid and non-solid software (see table below).
a. With a 3D SOLID software, life are much easier. For the best result, learn how to control the STL export options and, in most of the cases, you can SAVE AS STL a print ready file.
b. For Non Solid 3D software, a simple geometry can produce good results but, when the model is complex and the shape is curvy, printing from the exported STL file could be challenging.
c. A professional 3D printing service bureau will prefer to receive the 3D file in a solid neutral format (Step, XT and so,) rather than in STL format and to do the conversion to STL using their own tools.
d. When exporting 3D CAD file, avoid multi body and open surfaces. It is most recommended to save the file in a neutral format (_.XT, STEP, SAT…) and reopen it again to check for multibody, open surface, sketch, and suppress parts.

2. Chose the right Materials and Printing method

Transparent SLA part near opaque SLS
Each and every 3D printing method comes with a limited selection of materials which can be used for printing. The key factor to successful 3D printed project is to understand the available materials and what is the difference between each material and then, to choose the right material for the mission. For prototype model, don’t assume that the same material used with traditional fabrication will give the same results with 3D printing. For example, ABS is very popular plastic material, mostly with injection molding but, for a 3D printed prototype, Nylon 12 from a laser sintering printer (SLS) will give better results than ABS from FDM printer or ABS like materials from a jetting printer or even Nylon from FDM/FFF printer that filament and not powder. Another example is Glass filled Nylon, a very popular material to produce parts with SLS printers, but you can’t compare a GF nylon part with a injection molded Nylon filed with short glass fiber part. The same goes with metal printing. Laser sintering (SLM, DMLS) 3D aluminum parts fells short when you compare them to Aluminum machining parts, but 3D titanium parts have a very good mechanical property that are close to forging.
If you need clear plastic transparent parts, SLA method is the only good option but don’t expect the quality of traditional fabrication. The same goes for flexible printed parts with rubber or silicon like material, using SLA or multi jet printers.They are not a good substitution to traditional methods.

3 Adjust size, scale and tolerances

Each 3D printing technology comes with its limitations. You must learn the volume size, tolerances and minimal thickness limitations and adjust the 3D designed part to meet those limitations. Remember, the manufacturing process is done by sending your 3D files to a printer As It Is, and the printer operator can’t manipulate the 3D file geometry.
A scaled down project like architectural structure, an airplane or a vehicle model needs special care. Small details like railing, bars or windows needs extra care and different scaling ratio in order to meet the printer limitations. If you miss that part and print the file without fixing and adjusting the geometry, you may get very bed results.

4 The art of post processing

Hand painted SLS model near a plain one
With most printing methods, you will end up with a nice part in plain color and rough surface. For best results, post processing is needed. However, those processes require knowledge and the right equipment to get good results. For example, with metal printing, 
the most common post process is polishing and machining that can be done only by an expert with special tools. For plastic parts, polishing and dyeing are most common post process but, polishing and dyeing 3D printed plastic parts is challenging, especially for high quality results.

The lovely thing about 3D printing is that it is the simplest way to fabricate parts. A fast and cheap way to have a ready to use parts without the need to invest in expensive molds or special tools. However, as long as you remember that 3D printing has its limitation, and how to work around them, you will always have a successful 3D printing project.

Gal Raz
Managing Director of UCT Additive Manufacturing Center Singapore. Prior to joining UCT, Gal was the Additive Manufacturing Manager at the largest 3D printing service bureau in Israel. With over 20 years of diverse experience in business development, engineering, designing and innovation, he has vast knowledge in 3D CAD market.