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CAD Commands

2D & 3D CAD Commands There are a number of common

commands that are used in 2D and 3D CAD packages.

You have to know what these are and what they do.

The 2D CAD package used in this presentation is 2D Design.

The 3D software used is Rhino 3D, as used in industry.

Technology Technology Department Department

2D CAD Commands - Grids

Orthographic projection grid

Isometric projection grid

Iso top

Iso left Iso right


2D CAD Commands – Grid Snap

Grid snap only allows the cursor to follow the corners of the squares on the box.

This allows drawings to be produced quickly and accurately.


2D CAD Commands - Library A CAD library allows frequently used symbols

like sockets or doors to be selected from a pre-drawn catalogue and placed anywhere on the drawing.

This saves the user time and effort.


2D CAD Commands - Layers Layers can be used to draw different parts of a

drawing. For example the room layouts could be drawn

on one layer, the furniture layouts on another and the electrical fittings on another.

These layers can be viewed all together or one by one.

It is like drawing these parts on tracing paper and placing them on top of each other.

This allows the user to view different parts of a building plan individually to look at parts of particular interest.


2D CAD Commands - Zoom Zooming in allows you to see smaller parts of

a drawing in greater detail. Zooming out allows you to see the whole of a

larger drawing or can be used after you have zoomed in.

Zooming in Zooming out


2D CAD Commands – Line Types

You can draw the different line types needed for your drawing simply by selecting the line and selecting a line type for it.

By clicking on line type a menu of available lines appears. You simply select the type you require.


2D CAD Commands - Box/Circle/Arc

You can draw common shapes quickly and easily by selecting tools.

You can also choose how you want to configure these shapes. E.g. in the case of circle you can drag its size out or set it by typing in either its diameter or radius.


2D CAD Commands – Automatic Dimensioning

The computer calculates how long a line is or the diameter of a circle or the radius of a curve and automatically places this size on the dimension line.


2D CAD Commands – Copy & Paste

You can copy parts of a drawing that will be repeated and paste these parts elsewhere.

This is more suitable for either irregularly spaced copies or 1 copy of the same shape.


2D CAD Commands – Box Arrays

This allows shapes to be repeated in a predetermined order.

The user chooses how many shapes are to be repeated along the x-axis and the y-axis.

A box type shape is formed with the repeated parts hence the name box array.

An example of a box array with 2 repetitions along the x-axis and 3 repetitions along y-axis


2D CAD Commands – Ring Arrays

This allows shapes to be repeated in a circular pattern.

The user chooses how many shapes are to be repeated and the angle at which they are to be repeated.

The user can also control how many shapes are to be repeated going out from the centre of the revolution.

The user must then select the centre point of the ring array either by clicking on the drawing or typing a co-ordinate into the ring array instruction box.


2D CAD Commands – Ring Arrays

This is an example of a ring array with the instruction box shown alongside.


2D CAD Commands - Fillet This is when the user adds a curve

to a corner. In AutoSketch 6 this command is

called Trim Round.


2D CAD Commands - Chamfer This is when the user adds a 45°

line to a corner.


2D CAD Commands - Tangent This command allows the user to

draw a line at a tangent to a circle. This makes this type of line very

easy and quick to produce.

An example of lines of tangency drawn between 2 circles.


2D CAD Commands - Break This command lets the user delete

a part of a line without having to delete all of it and redraw what is needed to be kept.

This is quicker and easier to do than redrawing a whole line.

Line broken between these 2 points


2D CAD Commands - Trim This allows the user to either

extend a line to meet the edge of another shape or shorten a line to meet the edge of a shape.


2D CAD Commands - Trim

We will trim these 2 lines to the box, one will extend to reach the edge and one will be shortened to meet the edge.

Shortened lineExtended line


2D CAD Commands - Extend Extending a line is how we make it

longer

Drag the handles on the ends of the line to make it longer or shorter.


2D CAD Commands - Rotate This allows the user to turn an object

around any angle based on a centre point of rotation.

This box has been rotated by 45° with its rotation basepoint the centre of the rectangle.


2D CAD Commands - Scale This command allows the user to

say how much bigger or smaller they want to make a drawing they have done.

This makes scaled drawings much quicker and easier to do as a number of different scales can be produced using the 1 drawing.


2D CAD Commands - Mirror This command gives you a mirror

image of the shape you have drawn.

The user has to set where the mirror would be placed then the image is created.

The purple shape has been mirrored vertically along the left hand side.


3D CAD Drawing types - Wireframe

These types of drawings only show the structure of the object drawn.

No other details are shown.


3D CAD Drawing types – Surface Rendered

These types of drawings show the objects as solid shapes.



You can view surface detail as a rendered block.

It looks realistic due to the highlights and shading generated by the package.

Some packages like Rhino3D also allow you to add material to the shape.

This allows high quality drawings to be produced very quickly.



An Example is shown below.



This allows high quality drawings to be produced very quickly.

It also means that very realistic models of a design can be produced without having to manufacture them, saving design firms time and money.


3D CAD Drawings

As all 3D packages use different commands to produce shapes so you will not be asked to name any of these commands in your exam.

You should however, be aware of some of the things that can be done using these packages.


3D CAD Drawings There are certain things common to all

3D packages and this is how the shapes are produced.

You can: combine shapes subtract them from each other add them together obtain the orthographic views of the 3D

object using one command.


3D CAD Drawings – Combining Shapes

Shapes can be combined.


3D CAD Drawings – Subtracting Shapes

Shapes can be subtracted from each other.


3D CAD Drawings – Adding Shapes

You can add shapes to each other.


3D CAD Drawings - Orthographic Views You can use one command to

obtain the 3 orthographic views of the object.

Elevation

Plan

End Elevation


3D CAD Drawings

There are a huge number of other things you can do with 3D CAD packages.

It is because of the speed that these very realistic drawings can be produced at that design companies have moved to using these type of drawing packages.


3D CAD Drawings - Advantages An orthographic drawing of an object can

be produced by the software by clicking a button.

Very realistic objects can be designed very quickly.

Because these designs are so realistic and can be made to look like the actual material they will be made from, clients can see exactly what is being made so a physical model is not required, reducing costs and the time it takes to design a new product.


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