CAD Lab Viva Questions

Rajalakshmi Engineering College Department of Automobile Engineering GE 6261 – Computer Aided Drafting & Modelling Lab Viva – Voce Question & Answers 1.

What is meant by AutoCAD?

AutoCAD is one of the cad system software introduced in dec1982 by Autodesk ltd in Sausallia, California of USA. It has hit the technical world like shock wave revolutionizing the manner of drawing preparation. 2.

What is the diff between CAD & CADD? CAD-computer aided design, CADD-computer aided design and drafting

3.

What are the applications of CAD?

Design of machine elements, CNC machine tools, robotics etc Panel design and circuit layout Mapping, building plans, contour plotting and structural drawing Interior design and modeling 4.

Define absolute co-ordinates?

Values locating a point in space that describe its displacement from origin (0,0,0)point of the drawing. 5.

Define polar coordinates.

Values are locating a point in space that describes its location relative to the last point picked as defined by an angle and s distance. 6.

Define angular dimension? A dimension that measures the angle between two lines or the angle inscribed by an arc segment

7.

Define aligned dimension?

A linear dimension measuring the distance between two points. The dimension line for an aligned dimension is parallel to a line between points. 8.

What is By layer?

A value that can be assigned to colours and line types so that objects receive their colour and line type properties according to the layer they are on. 9.

What is command line?

A text window at the bottom of the screen that’s displays command: prompt. This is where you see what you are entering through the keyboard. Also called the command window. 10. What is command: prompt: A prompt at the command line, when no commands are currently running.

10.

Define polar co-ordinates.

Values are locating a point in space that describe its location relative to the last point picked as defined by an angle and its distance. 11.

What is cross hair cursor?

A form of the cursor that consists of a horizontal line and a vertical line intersecting at their midpoints, resembling the crosshair in a sighting device.

12.

Define dimension variables? A group of settings and values that control the appreance of dimensions.

13.

Define current UCS?

The user co-ordinate system that is active in a drawing. It determines the positive X,Y and Z direction. 14.

What is .dwg? The file extension and format for the standard AutoCAD drawing.

15.

Define graphics window?

The appearance of your screen when AutoCAD is running. It consists of the drawing area and surrounding toolbars, menu bars the command window and the status bar. 16.

Define line type? The style of appearance of a line. AutoCAD styles include continues, dashed, dash dot. And so on.

17.

What is a hatch patterns? A pattern of lines dots and other shapes that fills in a closed area.

18.

Define MIRROR?

A command that makes a copy of selected objects and flips the copy around a specified line to produce a reciprocal image of those objects. 19.

What is an ortho mode?

An on/off setting that, when on forces lines to be drawn and objects to be moved in a horizontal or vertical direction only. 20.

What are the advantages of CAD?

Greater productivity of the designer, improvement of design quality Easier design, calculation and analysis, quicker rate producing drawings, more accuracy of drawings, colour graphics is possible.

21.

What is an object snap mode?

Any of a set of tools precisely picking strategic points on an object, including end point, midpoint, center, and so on. It is casually called osnap. 22.

Define block?

The description of an association of AutoCAD objects that is stored with the drawing file and include a name, an insertion point, and a listening of objects in the association. 23.

Define relative co-ordinates?

Values are locating a point in space that describes its displacement from last point picked in the drawing rather than from the origin. 24.

What in ‘Anti-aliasing’?

Anti-aliasing is a advanced process for better illustration with multiple color gradations during drawing a line. 25.

Differentiate clockwise and counter clockwise rotation matrix. The direction of vector rotation is counterclockwise if θ is positive and clockwise if θ is negative

26.

Write down the eccentricity value for ellipse, parabola and hyperbola.

The value of eccentricity less than one is ellipses those with eccentricity equal to one are parabolas, and those with eccentricity greater than one is hyperbolas. 27.

Define Conic section.

A conic section is a curve created as the intersection of a cone with a plane. In analytic geometry, a conic may be described as a plane algebraic curve of degree two, and as a quadric of dimension two. 28.

Define ‘focus’ of a curve.

In geometry, the focus is pair of special points with reference to which any of a variety of curves is constructed. 29.

Write a short note ‘Hermite curve’.

A Hermite curve is a spline where every piece is a third degree polynomial defined in Hermite form: that is, by its values and initial derivatives at the end points of the equivalent domain interval. 30.

List out the various Bezier curves based on control points. Linear Bezier curve, Cubic Bezier curve and Quadratic Bezier curve.

31.

Write down the advantages and limitations of surface modeling. i.

Surface modeling can be used to check the real look of the product with coloring and shading.

ii.

Surface modeling can be used to perform interference checking.

iii. 32.

As the surface models precisely define the part geometry such as surface and boundaries, they can help to produce machine instructions automatically.

Write down two important solid modeling technique.

The solid modeling techniques permit for the automation of some complicated engineering calculations that are approved as a part of the design progression. Simulation, planning, and confirmation of processes such as machining and assembly were one of the initiations for the development of solid modeling technique. 33.

What is CGS?

Constructive solid geometry (CSG) is a method used in solid modeling for creating 3D models in CAD. Constructive solid geometry permits a modeler to make a complex surface by applying Boolean operators to join objects. Frequently CSG presents a model/surface that appears visually complex, but is essentially little more than cleverly combined. 34.

35.

Classify the Visualization. •

Visualization in geometric modeling

•

Visualization in scientific computing.

List out the various visualization approaches. •

Parallel projections •

36.

Perspective projection.

•

Hidden line removal

•

Hidden surface removal

•

Hidden solid removal

•

Shaded models

What is hidden line removal?

Hidden line removal (HLR) is the method of computing which edges are not hidden by the faces of parts for a specified view and the display of parts in the projection of a model into a 2D plane. 37.

Tolerance Analysis.

Tolerance analysis is a title to a different approaches applied in product design to know how deficiencies in parts as they are manufactured, and in assemblies, influence the ability of a product to meet customer needs. 38.

List out the international organizations involved to develop the graphics standards: •

ACM ( Association for Computer Machinery )

•

ANSI ( American National Standards Institute )

•

ISO ( International Standards Organization )

•

GIN ( German Standards Institute )

39. List out the various standards in graphics programming. IGES (Initial Graphics Exchange Specification) DXF (Drawing / Data Exchange Format) STEP (Standard for the Exchange of Product model data) 40.

Define NAPLPS

NAPLPS (North American Presentation- Level Protocol Syntax) describes text and graphics in the form of sequences of bytes in ASCII code. 41.

What are the activities of CAD? CAD activities include product design, engineering analysis and drafting.

42.

Give the general configuration of a CAD computer system. I.

Pcs were lower-cost, lower-quality toys that couldn't handle 3D.

Ii. Let the system requirements for your primary CAD application be your guide. iii. Choosing the CPU. Iv. Multi-monitor support. V. System Memory Vi. Solid-state drives. 43.

What is computer graphics?

The term computer graphics include almost every thing on computer that is not text or sound. It is an art of drawing pictures, lines. Charts, etc. Using computers with the help of programming. Or we can say that graphics is the representation and manipulation of image data by computer with the help from specialized software and hardware. Graphic designing is done using the various available softwares for computers which can produce the 3D images in the required shape and dimension. Computer graphics help us in getting the real display experiences. 44.

Write the important applications of computer graphic?

I. Computer graphics is used in the field of computer aided design. Ii. It is used to produce illustrations for reports or to generate slide for with projections. Iii. Computer graphic methods are widely used in both fine are and commercial are applications. Iv. The artist uses a combination of 3D modeling packages, texture mapping, drawing programs and CAD software.

45.

What are the raster and vector graphics?

RASTER- In computer graphics image, or BITMAP, is a dot matrix data structure representing a generally rectangular grid of pixels or points of color, viewable via a monitor, paper, or other display medium. Raster image are stored in image files with varying formats. VECTOR- Vector graphics is the use of geometrical primitives such as points, lines, curves, and shapes or polygon, which are all based on mathematical expressions, to represent image in computer graphics. “Vector”, in this context, implies more than a straight line. 46.

What are the hardware devices used for computer graphics? Input Devices Keyboard, Mouse, Data tablet, Scanner, Light pen, Touch screen, Joystick Output Devices Raster Devices- CRT, LCD, LED, Plasma screens, Printers Vector Devices- Plotters, Oscilloscopes.

47.

What is Autocad?

Autocad is a software program built to design and shape the 2-D and 3-D images. It provides the tools by which a detail design of the product can be done. It also has the option to create detailed design layout, which can be automatically drawn by using source model. 48.

What are the uses of Autocad?

Autocad can be used by the professionals to visualize the imaginary view of the product on a computer system. In Autocad, it is possible by the drafter to make the changes in the product before it gets finalized for design. It also gives the freedom for the designer to implement their various ideas and represent them to the suppliers or their clients. 49.

What are the fields where you see maximum use of Autocad?

Autocad is more popular among the architects, engineers and builders for developing their building layouts. 50.

What is the file formats used in design?

In Autocad, .dwg file format is used for design, it can be an interchangeable format. The file format which is interchangeable has the extension as DXF and operates data operability. It provides different languages which can be used as per the requirement. 51.

How you can create a user interface in Autocad?

User interface can be created by using the command prompts to draw the plots and dialog boxes. The dialog boxes can be displayed by the use of PLOT command and the external database commands (ASE). Setting of CMDDIA to 1, allows the dialog boxes to run the command. The user interface creation also needs the command line to display the entire file so that it can be edited or customized easily.

52.

What is the function of vertical integration?

To enhance the architectural designing of 3D object Autocad uses the vertical integration program. The 3D objects can include walls and other things that are associated with the data having information and simple objects like lines and circles. The data is programmed in such a way that it represents only the architectural products and the extracted files, and can be modified according to the requirement. 53.

What is the use of variant in Autocad?

In Autocad variants are used to help in creation, visualizing and rendering the 3D models that include 3D printing as well. Variants allows you to use the functionality of different application according to the requirement. 54.

55.

What are the benefits of using Autocad? •

Saves time and helps to increase the productivity

•

It helps to streamline your design and documentation workflow

•

Physical ‘3D’ prototype of the design can be quickly created by using Autocad

•

3D models can be directly imported into Autocad by using application like SolidWorks

What is the process to draw a line more than one time and save it automatically?

When a need arises to draw a new line the process opens up a new file in a new session to write the file. Autocad allows saving multiple drawing for each session. The files are saved by using the file extension .dwg and it can be modified by using the browser. 56.

What are the steps that enable the drag and drop feature in Autocad?

Autocad provides a way to drag and drop the elements by the use of “NOUN” and “VERB” in a dialog box. It allows the object to move from one place to another. Likewise, the remove or editing function can be done by using “MOVE and ERASE” 57.

What are the features corrected by Autocad?

Autocad detects the problem and correct it by removing the corruption with the drawing parts. With the available option of adding additional vertices, it also adds vertices to the poly-lines. The error can be corrected or neglected by finding out the exact location of the poly-line that has zero vertices. The object can be deleted or removed after there is no use of it in the system. 58.

How to set up a default drawing directory?

Default drawing directory has sub directories having the information using the windows commands. The applications, which are going to be used, are highlighted, and by using drag and drop features those application will be placed in the default directory. The properties for the application are selected from the menu and dialog boxes displayed on the front.

59.

How you can copy a closed drawing?

The copying of the closed drawing can be done by the designer center in the toolbar of the Autocad. By using the tree view option the copy of closed drawing can be done easily. The modification of the drawing can be done by using graphical interface. 60.

How you can hide the specific layers when plotting in Autocad?

To hide the specific layers while plotting, you can use various options like turning off the layers for plotting, freezing the layers and turning off. Turning off for plotting will show the layers on the screen but won’t output on printing. The layers that are turned off will hide the layers and also it will not appear on the screen. 61.

What is the process of copying the dimension styles from one drawing to another in Autocad? C

Copying of dimension styles require setting up the particular dimension style. To copy a dimension style, a new document has to be created. Once it is created, this document will be saved as a drawing template. A new reference will be created by new drawing template document and it will show all the options like layer style, units and blocks. Drawing can be done by seeing the current drawing and dimension style would be same as the original picture. By using the design center, Autocad tools can be used to copy the dimension styles from one drawing to another. 62. How can you remove the empty layers from drawing? The layers can be removed only when the object resides in the layers will be removed, once it is removed it is an empty layer. The empty layers cannot be deleted by purge. It might be because the layer is frozen on a viewport or referenced by an object in a block definition. By using EXPORT command it is possible to remove the layer from drawing, which results in creating a DXF file of the drawing. You can edit the dxf file in a text editor and rename all the instances of layers in the file, except the layer definition. 63.

Why Autocad WS is more popular among mobile users?

Autocad WS provides many option for mobile application developer like edit, view and share. They can easily share the application wherever they go and can develop an application in a matter of time. The application can be downloaded and installed from anywhere in the world, ignoring the licensing problem. The users can save file in any format and can run the application on any platform with ease. 64.

How can you make a spring, spiral or screw thread?

To make a spiral or screw thread use an AutoLISP routine such as spiral.1sp, it will create a spiral path according to your need. Then you can use EXTRUDE command with a reference object, using the spiral as the path. Also, there is another way you can do this, by using Mechanical Desktop (MDT) or Autosurf by using augmented lines as path. 65.

Tell me how you assign the keyboard characters or function keys to Autocad commands?

By editing the ACCELERATORS section of the Autocad menu file we can assign keyboard characters to Autocad commands.

66.

How you can open a drawing file that was created with the automatic save features?

Autocad files have an extension of “.dwg” and will only open those files having this extension. To open the drawing files you have to rename it, by using Explorer or DOS prompt you can do that. If you are using EXPLORER you have to make sure that the option of “Hide file extensions for known file types” is not enabled. After the file is copied you can rename and use the OPEN command in Autocad to open the drawing. 67. What will you do when command prompts appear on the command line instead of ASE dialog box and plot dialog box? In Autocad, CMDDIA variable controls the display of dialog boxes. To enable these dialog boxes you have to set CMDDIA to 1. 68.

In Autocad, what is the command that is used to rotate the grid at 45 degress? To rotate the grid at 45 degrees, command UCS is used.

69.

In what situation command prompt appears instead of a dialog boxes?

If a file command is imported from a script or AutoLISP/ ObjectARX/ ADSRX a command prompt appears instead of a dialog box. 70.

What are grips?

Grips are small boxes that appear on the objects you select. You can move or edit an object by dragging a grip.