AutoCAD 2D I Trimming and Extending PREPARED BY IAT Curriculum Unit January 2011 Institute of Applied Technology, 2011
Auto CAD Self-paced Learning Modules AutoCAD 2D Trimming and Extending Learning Outcomes: When you have completed the module, you will be able to: 1. Describe and apply the TRIM and EXTEND command to shorten and lengthen objects to meet cutting edges defined by existing objects. AutoCAD Geometry Lesson Regular Polygons Part 1 A polygon is any plane figure bounded by straight lines. A regular polygon is a polygon that has equal angles, equal sides and can be inscribed or circumscribed around a circle, see page 2. AutoCAD has a command to automatically construct polygons. For now, you will have to construct them with lines which will help you learn their geometry. The none most popular regular polygons are shown below. Trimming and Extending 2
Regular Polygons Part 1 - Continued Any regular polygon can be inscribed in or Circumscribed around a circles as shown Using a hexagon, right. It is important to understand and know the geometry involved to construct the triangle, square, hexagon, and octagone. An example of drawing a hexagon in AutoCAD is shown below. In Step 1, draw 6 lines from the center 60 degrees apart. Step 2, draw six lines from the end of one line to the end of the next line. Step 3, turn the construction layer off and you have your hexagon. Trimming and Extending 3
Trimming and extending Since you cannot draw every object using exact coordinate or locations as you have been doing in the past labs, you must learn to draw objects to approximate length and then trim or extend them to the exact location. This does not mean you can guess at the locations of the objects. You must still draw them with 100 percent accuracy. You can guess at their length and then adjust them with the TRIM or EXTEND command. These two commands are a big part of becoming more productive. AutoCAD Command: TRIM The TRIM command is used to shorten objects to meet the edges of other objects. It is not required for the objects being trimmed to intersect with the object forming the cutting edge. Command Line Syntax: or Command: TR 2004-2006 AutoCAD Command: EXTEND The EXTEND command is used to lengthen objects to meet the edges of other objects. It is not required for object being trimmed to intersect with the object forming the cutting edge. Command Line Syntax: Command: EXTEND or Command: EX 2004-2006 Trimming and Extending 4
Using the TRIM and EXTEND Command Study the object to be drawn. Instead of drawing it exactly from point to point as you have been drawing in the past modules, the object is drawn in their exact location, just not the right length. This way you can draw faster and require very little math. Complete the object. Current setting: Projection=UCS, Edge=Extend P1 1 found P2 1 found, 2 total P3 1 found, 3 total P4 1 found, 4 total P5 1 found, 5 total (Select the cutting edges, not the lines to be trimmed. Press enter or space.) Select object to trim or shift-select to extend or [Project/Edge/Undo]: P6 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P7 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P8 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P9 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P10 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P11 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P12 (Select the objects to be trimmed) Command: EXTEND Current setting: Projection=UCS, Edge=Extend P13 1 found P14 1 found, 2 total (Select the cutting edges, then press enter or space.) Select object to trim or shift-select to extend or [Project/Edge/Undo]: P15 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P16 Select object to trim or shift-select to extend or [Project/Edge/Undo]: (Now the objects to be extended.) Current setting: Projection=UCS, Edge=Extend P17 1 found Select object to trim or shift-select to extend or [Project/Edge/Undo]: P18 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P19 Command: Trimming and Extending 5
AutoCAD User Must Know No.15-1 It is important to remember while you are drawing in AutoCAD it is very rare that you are required to do any harder math then adding or subtracting. Let AutoCAD do the calculations for you. If you are using a calculator to complete the lab exercise in the AutoCAD Modules, you are not using AutoCAD to its capacity and you will take more time than necessary with the chance of making mathematical errors. AutoCAD User Tip 15-1 By setting the edge option to Extend, the Trim and EXTEND commands will extend or trim an object to the apparent intersection of the cutting edge and the trimmed or extended object. See example below. Command: EXTEND P0 1 found (Pick any object on the drawing.) Select object to trim or shift-select to extend or [Project/Edge/Undo]: E Enter an implied edge extension mode [Extend/No extend]: E (Set the edge to Extend. This sets both the TRIM and EXTEND commands.) Command: EXTEND P1 1 found Select object to trim or shift-select to extend or [Project/Edge/Undo]: P2 Enter an implied edge extension mode [Extend/No extend]: P3 1 found Select object to trim or shift-select to extend or [Project/Edge/Undo]: P4 Select object to trim or shift-select to extend or [Project/Edge/Undo]: Command: AutoCAD User Tip 15-2 With both the TRIM and EXTEND command, a very common beginner s error is picking the wrong objects first. Always select the cutting edge objects first, press the Enter or the Space key then pick the objects to be trimmed or extended. Trimming and Extending 6
AutoCAD User Tip 15-3 The TRIM and EXTEND commands can be interchanged. You can trim and extend in the same command. After you TRIM or EXTEND the objects, depending on the initial command you entered, hold down the shift key and then you can complete the opposite command. Study the example below: Command: EXTEND P1 1 found P2 1 found, 2 total (First, select the cutting edge, one for extending and one for trimming.) (Press Enter or Space.) Select object to trim or shift-select to extend or [Project/Edge/Undo]: P3 (Select the object to extend and hold down the SHIFT key.) Select object to trim or shift-select to extend or [Project/Edge/Undo]: P4 (AutoCAD will shift to the TRIM command and trim the line.) Select object to trim or shift-select to extend or [Project/Edge/Undo]: (Set the edge to Extend. This sets both the TRIM and EXTEND commands.) Command: AutoCAD User Tip 15-4 You can also extend and trim Arcs and fillets. P1 1 found Select object to trim or shift-select to extend or [Project/Edge/Undo]: P2 (Hold down the SHIFT key on the keyboard) Select object to trim or shift-select to extend or [Project/Edge/Undo]: P3 (AutoCAD will shift to EXTEND command and extend the line.) Select object to trim or shift-select to extend or [Project/Edge/Undo]: P4 1 found P5 1 found Select object to trim or shift-select to extend or [Project/Edge/Undo]: P6 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P6 Command: Trimming and Extending 7
Object Snap Modes for all Objects Mode Abbreviations Icon Marker The AutoCAD Object Perpendicular perp Using the Perpendicular Object Snap Command: LINE Specify first point: end of P1 (Start at the end of the line.) Specify next point or [Undo]: perp to P2 (Draw a line perpendicular to the line at P2.) Specify next point or [Undo]: Command: LINE Specify first point: end of P3 Specify next point or [Undo]: perp to P4 Specify next point or [Undo]: Command: LINE Specify first point: end of P5 Specify next point or [Undo]: perp to P6 Specify next point or [Undo]: Command: LINE Specify first point: end of P7 Specify next point or [Undo]: perp to P8 Specify next point or [Undo]: P9 1 found P10 1 found, 2 total P11 P12 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P13 Select object to trim or shift-select to extend or [Project/Edge/Undo]: P14 (Trim and change the vertical line to the construction layer.) Command: Trimming and Extending 8
Lab Exercise 15-1 Time Allotted: 30 min. Drawing Specifications Name Template Units Text Style Font AutoCAD 2D Lab 15-1 Module Template A Inches N/A N/A Note: Color, Linetype and Lineweight are all ByLayer unless otherwise instructed. Layering Scheme Objects on Layer Name Color Linetype Lineweight Construction Objects Construction 253 N/A N/A All Objects Object Red N/A N/A Instruction: 1. Setup the layers using the Layering Scheme above. 2. Draw the object shown below. 3. Check your drawing with the key. Trimming and Extending 9
Lab Exercise 15-2 Time Allotted: 30 min. Drawing Specifications Name Template Units Text Style Font AutoCAD 2D Lab 15-2 Module Template B Inches N/A N/A Note: Color, Linetype and Lineweight are all ByLayer unless otherwise instructed. Layering Scheme Objects on Layer Name Color Linetype Lineweight Construction Objects Construction 253 Continuous N/A All Objects Object Red Continuous N/A Instruction: 1. Setup the layers using the Layering Scheme above. 2. Draw the object shown below. 3. Check your drawing with the key. Trimming and Extending 10