How to CAD


You need to 3D print something? 
You want to make a digital version of your object? 
You need to create a 3D model on your computer? 

You need to CAD.


What is CAD?

CAD stands for ‘Computer Aided Design’ and has been around for many years with 2D capability, before launching into 3D. What started out in the 1970's as a niche product for drafting is now a staple of many people worldwide who want to design their own digital 3D content.

In terms of using CAD for invention, innovation, design, patents, and product development, there are so many positives for CAD. If your design involves many parts, you can create each part individually, assemble them digitally to see how they fit together, and create bills of materials. For each individual part you can specify the object materials (such as steel, ABS, PVC, glass etc.), and conduct finite element analysis on these parts – which allows you to find out how forces are distributed through the part, which in turn allows you to find weak spots in the part!



CAD for Prototype Creation?

CAD is also the main way to create objects for printing on 3D Printers, CNC Routers, Laser Cutters, and similar devices. You will create the digital version of an object, then give this object to a program which breaks down your 3D model into either ‘slices’ (which layer by layer, builds up a part from the base to the top at a slice thickness that you can set), or toolpaths (that a CNC router can follow to create your item on a tool-bed).



Which Program?

When selecting which program you want to use for CAD, you have MANY options. You need to decide how many dimensions you want to work in - are you only creating a 2D shape (like something that could be cut out from a piece of paper)? If not, you probably want to go with a more feature rich 3D CAD program.

2D: Creating objects in 2D is dominated by AutoCAD. This program is probably (as far as I can tell by experience) the most commonly used program for 2D CAD files. The common file format used is .DWG or .DXF. When creating these files, you will create a profile only. This can then be sent to a CNC router that accepts 2D profiles, and the machine will create a toolpath to create your object. There are other programs you can use, but you can’t beat AutoCAD.


3D: This is where things get a little more complex. 3D involves a whole extra dimension, which adds to the complexity of the design, and adds to the features that you would need. This also allows for a much greater capacity to create objects, and to analyse your objects for strengths and weaknesses, but may take longer to create those objects!

Typical programs include Solidworks, Autodesk Inventor, ProE, 123 Design, and SketchUp (amongst many more). I have personally used the first three (and am currently using Autodesk Inventor). I have found Solidworks to be the easiest to use so far, but Autodesk Inventor to have more options (though I am far from an expert in either application). If you need something feature rich, go for the Solidworks or Inventor. If you need something basic, go for the fee options such as 123 Design or SketchUp. These still offer tonnes of features, but have no price tag attached!



Caution: One big thing to check before purchasing or dedicating yourself to a product is to make sure that it outputs the designs you create into the correct formats! For instance, on most slicer programs, you need a .stl file, which Solidworks and Autodesk Inventor can easily handle. But for many CNC Routers, you may need .DXF files, which are 2D only, so are best handled by AutoCAD.

Whichever program or method you choose, I hope that you enjoy the process, and always keep learning! Keep at it, and you will succeed.


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