Welcome to Day three of our CNC E-Course. Today we are going to cover cad or computer aided design.

I’m Ivan irons and I have a website called CNC information.com and at any time you can go there and get some further information on CNC and the topic at hand.

Today we are going to have a general overview on computer-aided design. Lets go ahead and get started.  Really there are five steps in the CNC process and this is going to be the second one in that process.

CAD simply is translating our design that we did in step one into a computer format so we can manipulate it re-size its and then also save it for later. This is that flowchart that we saw yesterday and you can see were moving down this flowchart onto the next step, CAD. So what is cad? CAD stands for computer-aided design and a lot of times you'll hear people say computer-aided drafting as well. They are very similar and some say “CADD”, computer-aided design and drafting. This is a letter that term that was developed in the early 60s.

Imagine when we started developing computers and people saw the potential to bring those into production so they could be more exact and more precise when machining. That was called numerical control but some also saw how it could really help them how it's important in their drafting to be more exact.

That is where CAD showed up and was developed to more accurately describe the designs of parts of machines. People were after the blueprints or prints; you will hear both those terms interchangeably. Really, before computers the dimensions of all prints were hand-drawn and as you can imagine if every part on say of car a vehicle of some sort was hand-drawn there were quite few drawings. There were probably thousands and thousands of parts and part of those are dimensional area errors so you could have someone building parts that were inaccurate. This error would have to be re-machined later just because the print was bad. To accurately describe to those who have never seen a print here's a good look at one. This is just a very simple design with dimensions on it and multiple views. There are front, bottom and top views in this one.

What are the different types of CAD? There is 2-D and 3-D CAD. 2-D is two-dimensional as “x” and “y” axes. 3-D CAD adds another axis for depth.  CAD is vector-based and it's good to think of it like a drafting system. If you've ever taken drafting or were part of a hand-drawn drafting class CAD and drafting are very similar. You can make a round simple part and I say it's easier to use CAD for the design.

3-D CAD is really the future where you're getting into surface modeling and solid modeling. You're describing that part in all of its detail with 2-D CAD and maybe it's just a different view that you're designing. However, with 3-D CAD you're able to spin the part around or spin the assembly around to look at all the different angles.

Here is a shot of the 2-D CAD. You will see there are a few different views but this is just a flat part with not a whole lot to it. You could draw this out on the piece of paper and that's why it's 2-D; there's an XY axis. Here's a look at the 3-D CAD shot. You'll see I just created this quick face in RhinoCam, but you'll see you can spin that around and look at all the different angles.

This is really the future of where I’m going and others also. There is another type and it shows up more in cam, which will talk about tomorrow. Its called 2.5D and its prismatic. All it does is give the first 2-D print that we looked some dimension or death or how thick the materialist is.

There is kind of a design process if you're building a assembly or a group or a machine. You start out with the part level down at the bottom and you build various parts, which merge together into a subassembly, which generally merge in the groups and then they go up to the machine level. Imagine this is just like in a car that part level may be some of the parts on the differential and a subassembly may be the differential and then the group level could be the entire axle group with tires and wheels everything on  and the machine level could be the actual car or truck going on the road. As you can see, there is kind of a aided design process or levels.

CAD software packages; this is always interesting. A lot of them will be described as 2-D or 3-D. Any 3-D program can do to 2D so that's kind of a differentiator. There are some free packages out there that are absolutely zero cost and then there is $10,000 packages out there and so on. Whatever you would want to spend you can find. A lot of that money depends on the different design tools that it comes with and how well it keeps track of those different CAD design levels we just looked at.  Really the new thing in the last five years is how does it integrate with other users.

As you can imagine you can have drafters and engineers in various levels a designing and all working on the same projects.  The high-end stuff today integrates between different users more than it ever has in the past so you can do a group projects versus individual and then merge them later. Here again the couple examples of different CAD software packages are Rhino, SolidWorks, AutoCAD, and Alibre. Those are just some of the popular ones that you'll run into.

This kind of final photo here: this is an example is a screen shot off my computer of different tool palettes and these happen to be RhinoCam tool palettes.  You'll see there's different dimensions that you can do you can create solids or surfaces curves, lines circles, different layers or you can extrude things. There is just a whole host of different tools there and this is probably say a third to a half of the different tools that rhino has inside of it.  This is really what you're paying for when you go to a CAD software program: how many tools does it offer you, how quickly and easily can you execute your design and get on to the next step. They are really after productivity here and these are the differentiators between those software packages and the tooling that they offer.

Tomorrow we go into cam or computer aided manufacturing so that's it for today. My name is Ivan irons, if you have any other questions you can go to CNC information.com thanks