LABORATORY MANUAL COMPUTER AIDED DRAFTING LAB ME-211-E

Transcription

1 LABORATORY MANUAL COMPUTER AIDED DRAFTING LAB ME-211-E 1

2 LIST OF EXPERIMENTS COMPUTER AIDED DRAFTING M E-211-E S. No. NAME OF EXPERIMENTS 1. To Implement Simple programs for the graphics representation of Transformation and Projections. 2. To Implement Simple programs for the graphics representation of Conic Sections, Cubic Splines and B- splines. 3. To Implement Simple programs for the graphics representation of Surfaces Bilinear, Bicubic surface patch and Bezier surface. 4. CADD Modelling for Construction of simple machine part and components. 5. Modelling of machine components for Surface of a diffuser Section 6. Modelling of machine components for Propeller 7. Modelling of machine components for Gear blank and other mechanical parts. 8. Modelling of machine components for Mechanical assembly of parts. 2

3 EXPERIMENT NO:-01 TITLE:- Setting up the drawing environment by setting drawing limit, drawing unit, naming the drawing, having layers, setting line up for different of layer using various types of live in orthographic drawing and sawing the drawing. THEORY:- DRAWING LIMITS: - This command is used to define the extant of drawing. This is also used for turning limits on orthographic limits are turned off by default which means that there is no restriction as to whose press can be picket and object drawn. When limit is on AUTO CAD will not allow point to be picked as co-ordinates entered of the specified drawing limits. If you try to pick a point outside the drawing limits. Command:- Auto CAD menu utilizes loaded. Auto CAD Express Tools Menu loaded. Command:!_ limits Reset Model space limits: Specify lower left corner or [ON/OFF] <0.0000,0.0000>: Specify upper right corner < , >:420,297 DRAWING UNITS:- SCLECITION OF SCALE:- As a general rule, everything you draw with auto cad should be drawn full size when drawing on full scale of drawing must be declared depending upon the size of object being drawn. UNITS:- LINEAR UNTS:- The seare fine different units type for you to choose from one of which is decimal of default. SAVE DRAWING: - Allows you to save fit under new name. A dialogue box will be appear giving a wish to save the file to a new plane. LAYERS: - This command allow is to create a multi layers drawn on. It allows you to control the colour, line type, activity and visibility of individual layer. PROCEDURE:- DRAWING UNITS:- Pull drawn formula units Keyboard units. When start the unit command the first ling seen in the drawing unit box and shown in the right. The box is divided into four. In a addition the lies section also allow to specify the direction in which are measured. 3

4 SAVE AS DRAWING FILE:- to across the save as command, select SAVE AS under the file menu, OR type save it a command = promp. TO CREATE A NEW LINE TYPE:- open the layer properties manager dialogue box, Click on the type name displayed in the row that indicates the properties at a layer. The select line type dialogue box will appear. TO LOAD A NEW LINE TYPE:- open the layer properties manager of dialogue box. Click on the line type name displayed in the row that indicates the properties at a layer. The select line type dialogue box will appear. TO CHANGE THE LINE THICKNESS:- open the layer properties manager diagram bow click on the line under the heading line cut in the line properties. TO DEVETE LAYER:- open the layer properties may diagram box, click on the layer name and then press del etc. and confirm the deletion by pressing OK. 4

5 EXPERIMENT NO:-02 TITLE: Layout drawing of a building using different layers and line colours indicating details using text commands Theory:- Layers:- Layers are like transparent overlays on witch you organize and group different kinds of drawing information. The objects you create have common properties including colors, linetypes, and lineweights. An object can assume these properties from the layer it is drawn on, or properties can be specifically assigned to individual objects. Color helps you distinguish similar elements in your drawings, while linetypes help you differentiate easily between different drafting elements, such as centerlines or hidden lines. Lineweights represent the size or type of an object through width, enhancing your drawing and increasing legibility. Organization layers and the objects on layers makes it procedure: Creating and Naming Layers: You can create and name a layer for each conceptual grouping (such as walls or dimension) and assign common properties to those layers. By grouping objects into layers, you can control their display and make changes quickly and efficiently. When you begin a new drawing, Auto CAD creates a special layer named 0. By default, layer 0 is assigned color number 7 ( White or black depending upon your background color), the CONTINOUS linetype, a lineweight of DEFAULT (the default setting for DEFAULT is. 01 inch or. 25 mm), and the Normal plot style. Layer 0 cannot be deleted or renamed. To create a new layer 1. From the Format menu, choose Layer. 2. In the Layer properties Manager, choose New. A new layer is displayed in the list with the temporary name LAYER1. 3. Enter a new name. 4. To create more than one layer, choose New again, enter the new layer name, and press ENTER. 5. Choose OK. Creates, loads, and sets linetypes: If you enter linetype at the Command prompt, LINETYPE displayed prompts on the command line. Enter an option [?/Create/Load/ Set]:?- List Linetypes Displays the select Linetype File dialog box (a standard file selection dialog box). After you select an LIN file, AutoCAD lists the linetypes available in a file. Create Create a new linetype and stores it in an LIN file. Enter name of linetype to create: AutoCAD displayed the create or Append Linetype File dialog box (a standard file selection dialog box). Specify the file to witch you want the linetype added. Descriptive text: Enter optional descriptive text Enter a linetype description up to 47 characters long. The description can be a comment or a series of indercores, dots, dashes, and spaces to show a simple representation of the linetype pattern. 5

6 Enter linetype pattern (on next line): A, Enter a series of numbers separated by commas. Enter positive values to specify lengths of dashes and negative values to specify lengths of spaces. Use a zero to represent a dot. The A in the pattern definition prompt specifies the pattern alignment used at the ends of individual lines, circles, and arcs. AutpCAD supports A-type alignment only. With A-type alignment, AutoCAD guarantees that lines and arcs start and end with a dash. The A is automatically included in the definition. If you use a text editor to create a line type, you must enter a at the beginning of the definition. After creating a line type, you must load it to make it accessible. You cannot create complex line types with LINETYPE. For more information, see chapter 2, Line types and Hatch Patterns, in the Customization Guide. Load: Loads a line type whose definition exists in a file. The acad. Lin file contains the standard line types. Enter line type (s) to load: Enter a name list AutoCAD displays the load or Reload Line type dialog box. Enter or select the file in which the line type you want to load is stored. Set: Sets the current line type. You can control the line type of objects individually or by layer. Specifies line type name or [?]<current>:enter a line type name,? to list all loaded line type names, by layer, or block, or press ENTER The line type you enter becomes the current line type. AutoCAD draws all new objects with this line type, regardless of the current layer. If the line type you request is not loaded, AutoCAD searches for its definition on the acad.lin file. If the type is neither loaded nor in acad.lin, AutoCAD reports this deficiency and returns you to the command prompt. If you enter by layer, new objects inherit the line type associated with the layer on which the object is drawn. If you enter by block, new objects are drawn using the CONTINUOUS line type until type are grouped into a block. Whenever you insert that block, the objects inherit the line type of the block. Lineweights: There are 28 line weights available to apply to plot styles tables. If the line weight you need doesn t exist in the list of line weights stored in the plot style tablr, you can edit an existing line weight. You can t add or delete line weights from the list in the plot style table. To edit a line weight o Double- click the plot style table file you want to edit to open it in the plot style Table Editor. o Choose either the Table View tab or the From View tab. o Choose Edit Line weights. o In the Edit Line weights dialog box, select the line weight you want to edit in the list. A check mark in the In Use column indicates which line weights have been assigned to plot styles in the plot style table file. o Edit the line weight value using any of the following methods: Press ENTER, edit the value, and then press ENTER again. Press F2, edit the value, and and then press ENTER. Choose Edit Line weight, edit the value, and then press ENTER. Right click and Choose Edit. Edit the value, and then press ENTER. Click to insert a cursor, edit the value, and then press RNTER. 6

7 NOTE If you change a line weight value, other plot styles that use the line weight also change. o Under Units for Listing, you can specify whether to display line weight in millimeters or inches. o Choose Sort Line weights to sort the list of line weights by value. When you edit a line weights to sort the list of line weights by value. When you edit a line weight value, it is rounded and displayed with a precision of four places past the decimal point. The precision is the same for both millimeters and inches. Line weight values must be zero or a positive number. If you create a line weight with a zero width, the line is plotted as thin as the plotter can create it. The maximum possible line weight value is 100 millimeters (approximately four inches). COLOR: If you enter color at the Command prompt, COLOR displays prompts on the command line. Enter default object color<current>: You can enter the color number(1though255) or the color name (the names for the first seven colors). For example, you can specify the color red by entering the ACI number 1 or the ACI name red. You can also enter by layer or by block. If you enter by block, AutoCAD draws all new objects in the default color (white or black, depending on your background color) until they are grouped into a block. When you insert the block in a drawing, the objects in the block inherit the current setting of COLOR. If you enter by layer, new objects assume the color assigned to the layer on which you create them. See the LAYER command for information about assigning a color to a layer. 7

8 EXPERIMENT NO:-03 TITLE:- To draw orthographic views (F.V, AND T.V) of safety value and naming the component of safety value. THEORY:- A safety value is used to limit the maximum pressure of steam in a boiler. It is generally fitted at the croun of a boiler. When the pressure of the steam rises above the specific limit (working pressure) the safety value open automatically to allow the steam to escape. Details of a safety value are shown in fig. the main components are- (i) C.I body (ii) Valve. (iii) Lever. (iv) Dead weight. The lower flauge of the body is required to the seating block of the boiler by bolts and in the upper flauge of a bran seat in fitted. The brass value is kept in the position on the seat by a pointed spindle fitted in the steel lever. The shape of the lever is such that its curved end fits against the knife edge of the fukrum and the other end supports the dead weight. In the normal position, the movement due to dead weight, above the fukurm is more than the movement due to steam pressure. When the pressure exceeds the set limit, the movement due to steam pressure increase 4es and overcomes the movement due to dead weight and the value opens. PROCEDURE:- first make the outer body with the help of tool box. Then seeing the fig. make rectangles and then by pressing the left mouse button put the components one by one. Arrange them where they are required. TO LOAD LINE TYPE:- open the layer properties manager dialogue box. Click on the line type name displayed on the row that indicates the properties of a layer. Then select line type, dialogue box will appear. To make a cylindrical shape, firstly make a rectangle and then make them circular at the ends. COMMANDS USED:- (i) OSNAP Command. (ii) Limit command. (iii) Extend command. (iv) Mirror command. (v) Trim command. (vi) Breach command. 8

9 EXPERIMENT NO:-04 AIM:- to make an isometric dimensional drawing of a connecting rod using isometric grid and snap. The connecting rod in the connection b/w the piston and crank shaft. It joins the wrist pin of the piston with the throw or crank pin of the crankshaft. The lighter the connection rod and piston greater the resulting power and lesser the vibration because the reciprocation weight is less. The rod is split to permit its being clamped round the crankshaft. The lining may either be in the form of a separate split shell with a steel backing. When a separate split shell line is used, it is held in place by the connecting rod cap and by bolts which clamp together the split parts of the liner. PROCEDURE:- TO MAK A LINE:- the line command allows to draw straight line. You can specify the desired starting and end point using either 2D or 3D co-ordinates. GRID:- This will make the whole screen into a graph paper (upper limit of the screen should be 100,100). COMMAND:- GRID (return) Grid spacing (X) or ON/OFF/snap/aspect: 10 (return) GRID SUB COMMANDS:- ON/OFF :- it acts as toggle for switching the grid on/off, on the screen OR (FT) also is a toggle. SPACING (X):- How far between grid pts. If you give a value in response To the spacing requirement. You will get up a grid with equal x and y Spacing. SNAP:- If you select snap or s, auto cad takes that you want the specification (as already entered in response to grid spacing requirements). ASPECT:- If you choose aspect or- A, auto cad take that you want to set Up grid with different x and y spacing. Then it will ask for different values of x and y. SNAP:- it makes the uses to move in comfortable increment say every 10mm or 20mm. (as specified by the user). ON.OFF:- it acts as toggle for switching the snap on or Fg dose the same toggling. ASPECT:- here also you can have different values of x and y. ISOMETRIC:- it gives you a grid like you would find on iso. GRAPH PAPER:- Here you can draw either top, front or L.H.S view of any item. While drawing isometric drawing we should be clear that it is not a 3D drawing. 9

10 TO MAKE A CIRCLE:- with this command you can draw a circle wherever you want. You need to give coordinate of the centre pt. and the radius. COMMAND:- Circle (return) 3P/AP/TTR/<center>10,10 (Return) Radius<diameter>: 20 (Return) 10

11 EXPERIMENT NO:-05 AIM: - To wake a quarter sectional isometric view of a cotter joint. THEORY:- COTTERS: - Cotters and temporary fastness and are used to hold two parts together where the parts are subjected to axial forces only. A cotter is a wedge shaped piece of wild steel, often rectangular in section tapered on one or both sides. It is usually driven in perpendicular to the axis of connected parts. Taper on it is provided to facilitate its driving in position and withdrawal and for lateral adjustments of connected parts. Of the taper is provided in excess, there is possibility of the cotters slipping sack. To should be used. COTTER JOINT:- A joint formrd by using a cotter is called a cotter joint. In the cotter joint, one rod and is formed into a socket and other called spigot end B forged to a diameter little larger than that of rods. The dimensions of rod end stock and should be such that the area of each across the slot is not lass than area of rod. 11