Here is how to use Orthographic Views & Construction Lines in AutoCAD
- Drafting tools in AutoCAD make it easy to create 2 dimensional orthographic views that are properly aligned.
- the most important tool for orthographic views is POLAR.
- You normally start a drawing by creating 1 or 2 orthographic views.
- when you add a feature in one view you can update the other view to reflect the new feature.
For example, you might begin the drawing of a V block by creating the end view first because it has the most information.
- the front view might begin as a simple rectangle that you align (vertically) with the end view.
- you could transfer features by drawing LINEs from Endpoint osnaps in the end view using the POLAR tool.
- then you could Trim these LINEs using the outline of the front view as the cutting edge.
Creating the third orthographic view is more challenging because you cannot transfer features using only the POLAR tool.
- one approach is to draw a construction line at 45 degrees that you can use to locate intermediate points.
- the location of this 45 degree construction line (relative to the other views) determines the location of the third view.
XLINEs are special construction line objects in AutoCAD that do not have any end points & they do not contribute to drawing extents.
- when you Zoom Out XLINEs are always visible
- when you Zoom Extents AutoCAD ignores XLINEs.
- Trim one side of an XLINE to create a RAY that has only one end point (you can use Ray to create RAYs directly) - Trim both sides of an XLINE to create a LINE.
- Use the Xline command to create XLINEs.
- pick two points (without selecting any options) to create an XLINE that passes through these points.
- you can continue to pick more through points in the same Xline command & each XLINE will pass through the same first point.
Specify a point or [Hor/Ver/Ang/Bisect/Offset]: (pick first point)
Specify through point: (pick second point)
Specify through point: ↵
The other Xline options can be practical in different situations.
- for example, you could use the Angle option with an angle of 45 to create the construction line shown on the previous page.
Specify a point or [Hor/Ver/Ang/Bisect/Offset]: A ↵
Enter angle of xline (0) or [Reference]: 45 ↵
Specify through point: (pick point) Specify through point: ↵
you can invoke these other Xline options from a shortcut.
practice: creating orthographic views tutorial in AutoCAD
- Close the drawing from the previous exercise if it is open.
- Open the T108_14.dwg drawing in your personal folder.
This drawing file contains only the outline profile of the end view.
- you will use this existing outline and the additional information in the sketch above to complete the three views shown above.
- you will use the POLAR tool and construction lines as described in the previous pages.
- Pick Draw + Rectangle. Invoke the Endpoint osnap shown below and left-click to use that point as the first corner then enter @5.25,1.5 as the opposite corner of the rectangle.
- Verify that the POLAR status bar button is On (left-click on it if it is Off).
- Pick Modify + Move. Enter L to select the last object. Press <enter> to signal AutoCAD that you have selected all objects. Pick any point for the base point and move your cursor to the left until the POLAR tooltip angle is 180 degrees. Then type 6.5 and press <enter> as the second point of displacement.
The front view is automatically aligned with the end view because you used the POLAR tool.
- Pick Draw + Line and invoke an Endpoint osnap shown and left-click to use this point as the first point of the LINE.
- Move your crosshairs to invoke the Polar: Intersection tooltip shown and left-click to use that point as the second point. Then press <enter> to complete Line.
In the next step you will create a hidden line using the same technique but you must first set the current layer to Hidden Lines.
- the current layer is Outline right now.
- Drop down the Layer list on the Object Properties toolbar
and select Hidden Lines to make this the current layer.
- Use a similar technique (steps 6 & 7) to transfer the hidden line shown below.
- Pick Modify + Trim. Select the LWPOLYLINE (rectangle) near P1 as the cutting edge and press <enter> to signal AutoCAD that you have selected all cutting edges. Then pick the LINEs near P2 and P3 to trim them & press <enter> to complete Trim.
- Pick Draw + Construction Line. Right-click in the drawing area to invoke a shortcut and select Angle. Enter 45 as the angle. Invoke the Endpoint osnap shown below & left-click to use this as the Through point. Then press <enter> to complete Xline.
The through point you pick determines the space between the front and top views.
- picking this point makes the space between views the same in both directions.
- Drop down the Layer list on the Object Properties toolbar and select Outline to make this the current layer again.
- Pan the drawing (if required) so the construction line above the right side of the end view is on-screen.
- Pick Draw + Line. Invoke the Endpoint shown and left- click to use this as the first point. Move your crosshairs up and invoke the Polar: Intersection tooltip shown below and left-click to use this as the next point (do not exit Line yet).
This LINE will be erased later on (you are really only interested in finding the point of intersection with the construction line).
- the Tracking tool can help you find this intersection point without having to create a temporary LINE.
- you can learn about Tracking in the Introduction To Tracking document.
- Press & hold <shift> while you right-click in the drawing area to invoke a shortcut of osnap overrides. Select Perpendicular.
- Invoke the Perpendicular tooltip shown below and left-click to use the marker shown as the next point. Then press <enter> to complete Line.
- Use a similar technique to create the LINEs from the other side of the end view.
- Use Line to create LINEs on either side of the top view using appropriate drafting tools.
- Transfer the remaining features from the end view to the top view as shown below using Line. Then use Trim & Erase so your drawing looks like the second illustration.
- Pick Draw + Circle + Center,Diameter. Press & hold <shift> while you right-click in the drawing area to invoke a shortcut. Select From.
- Invoke the Endpoint shown below as the base point and left-click to use this point. Then enter @0.5,0.5 as the offset distance to specify the CIRCLE center. Enter 0.5 as the CIRCLE diameter.
- Use a similar technique to create the three more CIRCLEs in the other corners or use Mirror if you prefer.
- Right-click on the OSNAP button in the status bar and select Settings in the shortcut menu.
- Clear the Center osnap and select Quadrant instead. Then pick OK to continue.
- Drop down the Layer list on the Object Properties toolbar and select Hidden Lines to make this the current layer.
- Use the construction line to transfer the edges of the holes using Quadrant osnaps. Create the hidden lines shown.
You can do half the work if you use Mirror to take advantage of the symmetry in this drawing.
- Use Trim & Erase to complete the drawing as shown below.
- Save the changes to this drawing and Close the file.