Part of this blog is to show stuff I do at work (mainly as I have a family opinion that I'm like Chandler from Friends and nobody knows what I actually do!). Some of the work I do is on a CAD system. CAD stands for Computer Aided Design - it's using a computer to make the object on the screen first to see how it goes together. Then from this you can make drawings to show how the parts are made. So, here's how the screen looks when I start:-
There are 3 squares you can see, these are the 3 planes you can draw on. Imagine you are sat at the table in the kitchen facing the door to the living room - you can either draw on the table top (1 plane), on the wall your looking at (1 plane), or on the wall to your left with the cooker on it (1 plane). The thing we will draw will be 3D, not just flat like a picture. I'm going to try and draw a wheel....
First I click on a plane and draw the outside shape of the wheel. The number tells the circle how big it needs to be in millimetres. The distance from one side of the circle to the other is called the diameter. The distance from the middle of the circle to the outside is called the radius.
This shape is now only 2D - it goes up and down the screen and across the screen. To make it 3D we have to tell the computer how thick / deep it is.
We now have a basic wheel shape, so I can start cutting bits out the middle to make it look more like a tractor wheel. To do this I draw another circle the size I want to cut out the middle (this bit is called sketching) and then instead of putting material on I tell it to chop it out.
Once I've cut all the bits out the middle I can start to put some tread on the outside, once again by drawing a sketch of the outline, then telling the computer it make it 3D by adding material. Here's one set of treads.
Now, I could draw all the treads by themselves, but this would take ages. Instead I can tell the computer to copy the treads I've drawn and pattern them around the wheel. I tell it which bits to copy, where they need to be copied to and how many I want, then I end up with this.
All the little blue dotted lines you can see are all the edges on the other side of the wheel - if the wheel was made of glass so you could see through it these are what you would see.
Finally, the best bit - COLOURING IN!
If you look at all the pictures together you'll see on the left there's a box with lots of writing in that gets bigger as more information gets put on to the model. Each thing I do get's recorded here (it's sometimes called the model tree) - so if I need to change anything I can just click on the one I want to change and edit it.
So, that's how to do a simple thing like a wheel. In real life every part of the tractor would be modelled. These would then be put together in small blocks called assemblies, then these assemblies would be put with other assemblies to make the whole tractor. Then you can do some really clever stuff with it like this:-
