# Computer Aided Engineering Drawing الرسم الهندسي المعان بالحاسوب Lecture TWO CAD / CAD Engineering Dr. Tahseen Fadhil Abbas 2012-2013.

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Computer Aided Engineering Drawing الرسم الهندسي المعان بالحاسوب Lecture TWO CAD / CAD Engineering Dr. Tahseen Fadhil Abbas 2012-2013

Circle creation In this lecture we will investigate how circles can be created by adding several to the squares created in the previous lecture, so: Open your Inclass Ex1.dwg to display the six squares created in lecture 1.

AutoCAD 2002 allows circles to be created by six different methods and the command can be activated by : icon selection menu bar selection or keyboard entry. When drawing circles, absolute coordinates are usually used to specify the circle centre

Centre - Radius Select the CIRCLE icon from the Draw toolbar and: prompt Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: enter 60,100 – the circle centre point prompt Specify radius of circle or [Diameter] enter 15 – the circle radius. C1

Centre - Diameter From the menu bar select Draw-Circle-Center,Diameter and: prompt Specify center point for circle or.. enter120,100 prompt Specify diameter of circle enter 40 C2

Two points on circle diameter At the command line enter CIRCLE and: prompt Specify center point for circle or.. enter 2P – the two point option prompt Specify first end point on circle’s diameter enter 120,200 prompt Specify second end point on circle’s diameter enter 160,240 C3

Three points on circle circumference Menu bar selection with Draw-Circle-3 Points and: prompt Specify first point on circle respond pick any point within the top right square prompt Specify second point on circle respond pick another point within the middle left square prompt Specify third point on circle respond drag out the circle and pick a point. (middle right or left square) C4

TTR: tangent-tangent-radius a)Menu bar with Draw-Circle-Tan,Tan,Radius and: prompt Specify point on object for first tangent of circle Respond move cursor on to line L1 and leave for a second and 1. a small marker is displayed 2. Deferred Tangent tooltip displayed respond pick line L1, i.e. left click on it prompt Specify point on object for second tangent of circle respond pick line L2 prompt Specify radius of circle enter 35 and a circle is drawn as tangent to the two selected lines. C5

TTR: tangent-tangent-radius b) At the command line enter CIRCLE and: prompt Specify center point for circle or.. enter TTR – the tan,tan,radius option prompt first tangent point prompt and: pick line L3 prompt second tangent point prompt and: pick line L4 prompt radius prompt and enter: 25 and a circle is drawn tangential to the two selected lines, line L4 being assumed extended. C6

TTT: tangent-tangent-tangent a)Menu bar with Draw-Circle-Tan,Tan,Tan and: prompt Specify first point on circle and: pick line L4 prompt Specify second point on circle and: pick line L5 prompt Specify third point on circle and: pick circle C6 C7

TTT: tangent-tangent-tangent b) Activate the Draw-Circle-Tan,Tan,Tan sequence and: prompt Specify first point on circle and: pick circle C1 prompt Specify second point on circle and: pick circle C2 prompt Specify third point on circle and: pick circle C3 Circles have been drawn tangentially to selected objects, these being: a) two lines and a circle b) three circles. C8

Saving the drawing Assuming that the CIRCLE commands have been entered correctly, your drawing should resemble Fig. below (without the text) and is ready to be saved for future work.

Saving the drawing From the menu bar select File-Save As and: prompt Save Drawing As dialogue box with 1. Begin folder name active 2. File name: Inclass Ex2. respond pick Save

Saving the drawing

Inclass Ex3

Home Work2 Modify: Fillet & Chamfer

THANK YOU