Sacramento City College Engineering Design Technology Drawing Basic Shapes Sacramento City College Engineering Design Technology Drawing Commands

Objectives The CIRCLE command Use the @ symbol function The CIRCLERAD system variable Use the @ symbol function The LASTPOINT system variable The ARC command The POLYGON command The ELLIPSE command The RECTANGLE command The DONUT command. Drawing Commands

Drawing Commands

Drawing Circles Drawing Commands

Drawing Circles The CIRCLE command: Enter C or CIRCLE at the Command: prompt OR Pick the Circle button in the Draw toolbar Select Circle from the Draw pull-down menu Drawing Commands

Drawing Circles A circle can be drawn by: 1. Radius. 2. Diameter. 3. Two point. 4. Three point. 5. Tangent to two objects. 6. Tangent to three objects. Drawing Commands

Drawing Circles By Radius The radius is the distance from the center to the circumference of a circle or arc. The circumference is the perimeter or distance around the circle Circumference Radius Drawing Commands

Drawing Circles By Radius Method #1 – By Radius To draw a circle by specifying radius: Pick center point. Specify radius with mouse. The radius value chosen becomes the default setting for the next time you use the CIRCLE command. Drawing Commands

The CIRCLERAD System Variable Drawing Commands

The CIRCLERAD System Variable Use the CIRCLERAD variable to set a radius default. You can then draw circles of the exact same size. Circle, pick center, [Enter] CIRCLERAD variable is automatically reset every time you draw a circle. Drawing Commands

The CIRCLERAD System Variable When the CIRCLERAD variable is set: Pick the circle center point. Press [Enter]. Circle is drawn with radius = CIRCLERAD Size of circle comes from value of CIRCLERAD Set CIRCLERAD to 0 if you don’t want a default value for a circle OR Pick new radius with mouse. Drawing Commands

Drawing Commands

Drawing Circles Drawing Commands

Drawing Circles By Diameter Method #2 – By Diameter A circle can also be drawn by specifying the diameter. Command: C or CIRCLE 3P/2P/TTR/<Center point>: (pick the center point) Diameter/<Radius>: D Diameter: (Drag the circle to the desired diameter) Command: Drawing Commands

Drawing Circles By Diameter Watch the screen carefully. The pointer measures the diameter but the circle passes midway between the center and the cursor. See Fig. 5-4. Drawing Commands

Drawing Commands

Drawing Circles By Diameter If you use the Diameter option, the previous default radius setting is converted to a diameter. If you use the Radius option, the previous Diameter option is converted to a radius. Drawing Commands

Drawing a Two Point Circle Drawing Commands

Drawing A Two Point Circle Method #3 – By Two Points A circle can be drawn by specifying two points. Pick two points on opposite sides of the circle. Use when diameter is known, but the center is difficult to find. Drawing Commands

Drawing Commands

Drawing A Three Point Circle Drawing Commands

Drawing A Three Point Circle Method #4 – By Three Points on Circle A circle can be drawn by picking three points on the circumference of the circle. Use when three points on the circumference of the circle are known. AutoCAD calculates the radius from the three points picked. Drawing Commands

Point #3 – not yet selected Drawing Commands

Drawing a Circle Tangent to Two Objects Drawing Commands

Circle Tangent To Two Objects Method #5 – Tangent to 2 Objects at a given radius (TTR) The term tangent refers to a line, circle or arc that comes into contact with an arc or circle at only one point. That point is the point of tangency. A line drawn from the circle’s center to the point of tangency is perpendicular to the tangent line. Drawing Commands

Circle Tangent To Two Objects Point of Tangency Is an extremely important geometric relationship. Is used in engineering/architecture Examples Constructing an exit ramp on freeway. Determining the start/end point of a curve on an object. Drawing Commands

Point of Tangency Point of Tangency Line forms a Right Angle at the Point of Tangency Drawing Commands

Circle Tangent To Two Objects Drawing Commands

Circle Tangent To Two Objects Method #5 – Tangent to 2 Objects at a given radius (TTR) The Tan, Tan, Radius (TTR ) option is used to Draw a circle tangent to two objects and To a specific radius. Drawing Commands

Circle Tangent To Two Objects Command: C or CIRCLE 3P/2P/TTR/<Center point>: TTR Enter Tangent spec: (pick first item) Enter second Tangent spec: (pick second item) Radius <current>: (type a radius value, press [Enter]) Command: Drawing Commands

Circle Tangent To Two Objects If the radius entered is too small, AutoCAD gives you the message: “Circle does not exist.” Drawing Commands

Drawing a Circle Tangent to Three Objects Drawing Commands

Circle Tangent To Three Objects Method #6 – Tangent to Three Objects (TTT) The Tan, Tan, Tan option allows you to draw a circle tangent to three existing objects. Command: C or CIRCLE 3P/2P/TTR/<Center point>: 3P First point: TAN Second point: TAN Third point: TAN Command: Drawing Commands

Circle Tangent To Three Objects You will see a deferred tangent marker when you select the first two objects. A deferred tangent marker means AutoCAD is aware that you have chosen those objects, but it must wait for additional input before the circle can be drawn. Drawing Commands

Drawing Commands

Drawing Commands

Drawing Commands

Drawing Commands

Using the @ Symbol Drawing Commands

Using the @ Symbol The @ symbol has 3 Functions 1. To draw with relative and polar coordinates. 2. To enter the “@” sign. 3. To input the coordinates last entered (recall LASTPOINT system variable) Drawing Commands

Using the @ Symbol Suppose you want to draw a circle with a center at the end of the line just drawn. The LASTPOINT system variable is set to the x,y coordinate of the end of the line. Execute the CIRCLE command, but Enter the @ symbol when asked for a center point. The center point will be located at the endpoint of the line just drawn. Drawing Commands

Using the @ Symbol LASTPOINT system variable is set to this X, Y value with the mouse click The LASTPOINT system variable can then be used as the center of the circle by recalling that X,Y value with the @ symbol Drawing Commands

Using the @ Symbol The @ symbol automatically recalls the last coordinates as the center of the circle. The @ symbol retrieves the LASTPOINT system variable value. Drawing Commands

Using the @ Symbol The LASTPOINT value is the last X,Y coordinate set clicked with the mouse when asked for graphic x,y input. Each time you make a pick with the mouse, the LASTPOINT system variable is reset. Drawing Commands

Using the @ Symbol #2 Another application of the @ symbol is to draw concentric circles. Execute the CIRCLE command and draw the first circle. Execute the CIRCLE command again, and enter the @ symbol when asked for the center point. Drawing Commands

Drawing Arcs Drawing Commands

Drawing Arcs An Arc Eleven options (!) are available for drawing arcs. Is any part of a circle or curve. Is dimensioned with a radius. Can be drawn a number of different ways. Eleven options (!) are available for drawing arcs. Drawing Commands

Drawing Arcs Many ways to draw arcs Three point Arc. Start, Center, End. Start, Center, Angle. Start, Center, Length. Start, End, Angle. Start, End, Radius. Start, End, Direction. Center, Start, End. Center, Start, Angle. Drawing Commands

Drawing Arcs Center, Start Length of chord. Continuing Arcs from previously drawn lines/arcs. Drawing Commands

Drawing Arcs An Arc can be drawn Clockwise Counterclockwise OR Counterclockwise The arc is dragged into position as the endpoint is located. Drawing Commands

Drawing Arcs Three-point arc. Specify Start point Second point along the arc The endpoint. Drawing Commands

Drawing Arcs Three-point arc Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: (select the second point on the arc) End point: (select the arc’s endpoint) Command: Drawing Commands

Drawing Arcs Start, Center, End option Use this option if you know the start, center, and endpoints Picking the start and center points establishes the arc’s radius The point selected for the endpoint determines the arc length The selected endpoint does not have to be on the radius of the arc Drawing Commands

Drawing Arcs Start, Center, End option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: C Center: (select the arc’s center) Angle/Length of chord/<End point>: (select the arc endpoint) Command: Drawing Commands

Drawing Arcs Start, Center, Angle option When the arc’s included angle is known, this may be the best choice The included angle is the angle formed between the center, start, and endpoints of the arc The arc is drawn counterclockwise unless a negative angle is specified Drawing Commands

Drawing Arcs Start, Center, Angle option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: C Center: (select the arc center point) Angle/Length of chord/<End point>: A Included angle: 45 Command: Drawing Commands

Drawing Arcs Start, Center, Length option Standard chord lengths are specified in the chord length table (Appendix I) Arcs are drawn counterclockwise A positive chord length gives the smallest possible arc with that length A negative chord length gives the largest possible arc Drawing Commands

Drawing Arcs Start, Center, Length option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: C Center: (select the arc center point) Angle/Length of chord/<End point>: L Length of chord: (enter the length of the chord) Command: Drawing Commands

Drawing Arcs Start, End, Angle option An arc can be drawn by picking the start point, endpoint, and entering the included angle A positive included angle draws the arc counterclockwise A negative included angle draws the arc clockwise Drawing Commands

Drawing Arcs Start, End, Angle option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: E End point: (select the arc end point) Angle/Direction/Radius/<Center point>: L Included angle: Command: Drawing Commands

Drawing Arcs Start, End, Radius option A positive radius value results in the smallest possible arc between the start and end points A negative radius gives the largest arc possible Arcs can only be drawn counterclockwise with this option Drawing Commands

Drawing Arcs Start, End, Radius option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: E End point: (select the arc end point) Angle/Direction/Radius/<Center point>: R Radius: (enter value of arc radius) Command: Drawing Commands

Drawing Arcs Start, End, Direction option Enter start point, end point and direction of rotation in degrees The distance between the points and the number of degrees determines the arc’s location and size The arc is started tangent to the direction specified Drawing Commands

Drawing Arcs Start, End, Direction option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: E End point: (select the arc end point) Angle/Direction/Radius/<Center point>: D Direction from start point: Command: Drawing Commands

Drawing Arcs Center, Start, End option This option is a variation of the Start, Center, End option Use this option when it is easier to begin by locating the center Drawing Commands

Drawing Arcs Center, Start, End option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: C Start point: (select the arc center point) Angle/Length of chord/<End point>: Command: Drawing Commands

Drawing Arcs Center, Start, Angle option This option is a variation of the Start, Center, Angle option Use this option when it is easier to begin by locating the center Drawing Commands

Drawing Arcs Center, Start, Angle option Command: A or ARC Command: Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: C Center: (select the arc center point) Start point: (pick the start point) Angle/Length of chord/<End point>: A Command: Drawing Commands

Drawing Arcs Center, Start, Length of chord option This option is a variation of the Start, Center, Length option Use when it is easier to begin by locating the center Drawing Commands

Drawing Arcs Center, Start, Length of chord option Command: A or ARC Center/<Start point>: (select the first point on the arc) Center/End/<Second point>: C Center: (select the arc center point) Start point: (pick the start point) Angle/Length of chord/<End point>: L Length of chord: (pick or type the chord length) Command: Drawing Commands

Drawing Arcs Continue arc from previously drawn line or arc. Pick Draw, Arc, Continue from the pull-down menu When a series of arcs are drawn in this manner, each consecutive arc is tangent The start points and endpoints are taken from the endpoint and direction of the previous arc. Drawing Commands

Drawing Arcs Continue arc from previously drawn line or arc. The Continue option can be used to quickly draw an arc tangent to the endpoint of a previously drawn line. Drawing Commands

Ellipses Drawing Commands

Drawing Ellipses Ellipses have a center, and major and minor axes. Major axis is the long axis. Drawing Commands

Drawing Ellipses Drawing Commands

Drawing Ellipses When a circle is viewed at an angle, an elliptical shape is seen. A 30o ellipse is created if a circle is rotated 30o from the line of sight. Drawing Commands

Ellipses 60 degree ellipse Circle Drawing Commands

The ELLIPSE Command When drawing ellipses Choose the appropriate option based on the information you know about locating and constructing the ellipse. Drawing Commands

The ELLIPSE Command The ELLIPSE Command Options: Center Option Specify center Endpoint of first axis Endpoint of second axis Drawing Commands

The ELLIPSE Command The ELLIPSE Command Options: Axis, End Option Specify first endpoint of an axis Second endpoint of the SAME axis One endpoint of second axis. The axis can be the major or minor axis Rotation Option Drawing Commands

The ELLIPSE Command The ELLIPSE Command Options: Rotation Option Specify the angle at which a circle rotates from the line of sight. Center Rotation angle Drawing Commands

The ELLIPSE Command Axis, Endpoint option Command: EL or ELLIPSE Arc/Center/<Axis endpoint 1>: select an axis endpoint Axis endpoint 2/<Second point>: select the other endpoint of the axis <Other axis distance>/Rotation: select a distance from the midpoint of the first axis to the end of the second axis and press [Enter] Command: Drawing Commands

The ELLIPSE Command Axis, Endpoint option Command: EL or ELLIPSE Arc/Center/<Axis endpoint 1>: (select a major axis endpoint) Axis endpoint 2: (select the other endpoint of the major axis) <Other axis distance>/Rotation: R Rotation around major axis: (type a rotation angle) 30 Drawing Commands

Drawing Regular Polygons Drawing Commands

Drawing Regular Polygons A regular polygon is any closed-plane geometric figure with three or more equal sides and equal angles. Drawing Commands

The POLYGON Command To draw a regular polygon. Command: POL Command: Enter number of sides: <4> Enter number of sides desired Specify center of polygon or [Edge]: pick center of polygon. Enter an option [Inscribed in circle/Circumscribed about circle] <I>: I Specify radius of circle: specify radius with mouse Command: Drawing Commands

The POLYGON Command Inscribed Polygons A polygon is inscribed when it is drawn inside a circle and its corners touch the circle. Drawing Commands

Inscribed Drawing Commands

Drawing Regular Polygons Circumscribed Polygons are drawn outside of a circle the sides of the polygon are tangent to the circle. Specify the radius of the circle with the mouse. Drawing Commands

Circumscribed Drawing Commands

Drawing Regular Polygons The Edge option Use when location of center of polygon is unknown. Specify first endpoint of one side of polygon Specify second endpoint of same side of polygon Drawing Commands

Drawing Polygons - Hexagons Bolt heads and nuts on mechanical drawings are commonly drawn as hexagons and are normally dimensioned across the flats. Draw bolt and nut polygons with circumscribed. The radius you enter is equal to 1/2 the distance across the flats. Drawing Commands

Drawing Commands

The RECTANGLE Command Drawing Commands

Drawing Rectangles Rectangles are constructed with polylines Can be edited with the PEDIT command. We will learn the PEDIT command later. A rectangle, since it is a polyline is treated as one entity until it is exploded. We will learn the EXPLODE command later. Drawing Commands

Drawing Rectangles Rectangles are drawn with the RECTANGLE command. Pick first corner of rectangle. Pick second corner of rectangle. Drawing Commands

Drawing Rectangles Command: REC or RECTANG Command: Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: select the first corner Specify other corner point or [Area/Dimensions/Rotation]: select the second corner Command: Drawing Commands

The RECTANGLE Command RECTANGLE Command Options Chamfer Fillet Width - used to adjust the width of line of rectangle Elevation – 3D application – not discussed here Thickness – 3D application – not discussed here Area Dimensions Rotation Drawing Commands

The RECTANGLE Command RECTANGLE Command Options Chamfer - specify by chamfer distance Fillet - specify by fillet radius Drawing Commands

Drawing Rectangles Drawing Rectangles with Line width Width option is used to adjust the width of the line of rectangle in the X-Y plane. Command: REC or RECTANG Chamfer/Elevation/Fillet/Thickness/Width<First corner>: W Width for rectangles <current> : .03 Command: Drawing Commands

Drawing Commands

Drawing Rectangles Drawing chamfered rectangles A chamfer is an angled corner on an object. To draw chamfers on a rectangle use the Chamfer option. Provide the chamfer distances. Drawing Commands

Drawing Commands

Drawing Rectangles Drawing filleted rectangles A fillet is a slightly rounded corner on an object. Drawing Commands

Drawing Rectangles Command: REC Command: Current rectangle modes: Fillet=1.0000 Width=0.1000 Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: C Specify first chamfer distance for rectangles <1.0000>: 2 Specify second chamfer distance for rectangles <1.0000>: 2 Specify first corner point or [Chamfer/Elevation/Fillet/Thickness/Width]: Specify other corner point or [Area/Dimensions/Rotation]: Command: Drawing Commands

Drawing Commands

The RECTANGLE Command RECTANGLE Command Options Area Dimensions Rotation Drawing Commands

The DOUGHNUT Command Drawing Commands

The DOUGHNUT Command The DOUGHNUT Command Creates a circle with a thick line OR A filled circle Doughnuts drawn in AutoCAD are actually circular polylines. Drawing Commands

The DOUGHNUT Command Command: DONUT (DOUGHNUT) (DO) Command: Specify inside diameter of donut <0.5000>: Specify outside diameter of donut <1.0000>: 2 Specify center of donut or <exit>: Command: A “0” inside diameter the produces a solid circle. Drawing Commands

Drawing Doughnuts The FILL mode When the FILL mode is turned off, donuts appear as segmented circles or concentric circles. When the FILL mode is turned on, donuts appear as filled in circles. Drawing Commands

Fill ON Drawing Commands

Drawing Doughnuts FILL can be used transparently Enter ‘FILL wile inside the DONUT command Enter ON or OFF as needed. The fill in previously drawn doughnuts remain on until the drawing is regenerated Drawing Commands

Fill OFF Drawing Commands