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AutoCAD Tutorial Object Snap Free Ebook Download

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AutoCAD Tutorial Object Snap

                                                AutoCAD Tutorial Object Snap free download         

The Object Snaps (Osnaps for short) are drawing aids which are used in conjunction with other commands to help you draw accurately. Osnaps allow you to snap onto a specific object location when you are picking a point. For example, using Osnaps you can accurately pick the end point of a line or the center of a circle. Osnaps in AutoCAD are so important that you cannot draw accurately without them. For this reason, you must develop a good understanding of what the Osnaps are and how they work.

This tutorial describes the use of all the osnaps. There are a number of worked examples which demonstrate Osnaps in use. Following these examples is probably the best way to understand the logic of Osnaps and to get an idea how they might be used in drawing practice. The tutorial also includes sections on tracking and the use of point filters. If you just need information quickly, use the QuickFind toolbar below to go straight to the information you need or select a topic from the contents list above.

An Example
This simple example is to give you an idea how Osnaps work. Follow the command sequence below to draw a circle and then to draw a line from the center point of the circle to a point on the circle's circumference at the 12 o'clock position.

To Draw the Circle
Command: CIRCLE
Specify center point for circle or [3P/2P/Ttr (tan tan radius)]: (pick a point in the middle of the drawing window)
Specify radius of circle or [Diameter]: (pick another point to draw the circle, the size is not important)

When you use Osnaps you need only pick a point which is near to the point required because AutoCAD automatically snaps to the object location implied by the particular Osnap you use. Notice that when you move the cursor close enough to an Osnap location, it is highlighted with an Osnap marker. Each Osnap has a different marker. As you have already seen, the Center Osnap marker is a circle and the Quadrant Osnap marker is a diamond. Notice also that when you move the cursor over a snap point the cursor jumps to the snap location. This feature is known as Magnet.

One thing that often catches new users out is that when you want to snap to the centre of a circle, the cursor must pass over the circle's circumference. This is because the circle has no solidity, it is only an outline.

Although you can get quite close to the result above by picking freehand you will never be able to pick as accurately as you can using Osnaps. Many AutoCAD commands rely upon the fact that objects have been drawn accurately and so you should always use Osnaps when you need to pick a point at a particular location.

There are four basic methods of accessing the Osnaps:

The Osnaps are available from a flyout button on the Standard toolbar, see illustration on the right.
The Osnaps are also available on their own Object Snap toolbar. If this toolbar is not already displayed, you can display it using the TOOLBAR command, ViewToolbars… from the pull-down menu. When the Toolbar dialogue box appears, simply check the box next to "Object Snap" in the toolbars list. Many AutoCAD users work with the Object Snap toolbar permanently docked on their screen because it gives one-click access to all of the Osnaps, making drawing much more efficient.
You can also access the Osnaps from the cursor menu. Hold the Shift key down on the keyboard and right-click the mouse to bring up the cursor menu. The menu appears at the current cursor position.
Finally, you can also access the Osnaps from the keyboard by typing their abbreviated name. See the exercise above and the sections below for details.
The main reason for this flexibility in using the Object Snaps is that they are used very frequently. Experienced AutoCAD users will use Object Snaps all of the time because they are the only way to make sure that the objects you are drawing are drawn accurately. You must practice using Object Snaps until they become second nature.

There are thirteen Osnaps in all and although they are all useful in certain situations you will probably find yourself using about half of them on a regular basis and the other half in special circumstances. However, it's a good idea to get to know all of the Osnaps so that you can plan your drawing, knowing all of the tools at your disposal. A sensible use of Osnaps is the best way to improve your drawing efficiency.

Each of the sections below is accompanied by a small screen-shot illustrating the Osnap in use. In each case, drawing objects are shown in pale blue (cyan), the Osnap marker is shown in red and the cursor cross-hairs in white. The corresponding Snap Tip is also shown. Snap Tips appear if you let the cursor hover over an Osnap location for a second or so and have a similar function to the toolbar Tool Tips.

The Extension Osnap enables you to snap to some point along the imaginary extension of a line, arc or polyline segment. To use this osnap, you must hover the cursor over the end of the line you want to extend. When the line end is found, a small cross appears at the endpoint and a dashed extension line is displayed from the endpoint to the cursor, providing the cursor remains close to the extension. The Snap Tip for Extension also includes the relative polar co-ordinate of the current cursor position. This can be a useful guide for positioning your next pick point. The co-ordinate includes a distance from the endpoint and the angle of the extension. In the case of the arc extension, the Snap Tip displays the distance along the arc. See the Using Co-ordinates tutorial for more information on polar co-ordinates.

The Parallel Osnap is used to draw a line parallel to any other line in your drawing. In operation, this osnap is slightly less intuitive than some of the others. To draw a parallel line, first start the Line command, specify the first point when prompted and then start the Parallel Osnap. Hover the cursor over an existing line until you see the Parallel snap marker. Now, move the cursor close to a parallel position and a dotted line will appear, indicating the parallel. You can now pick the second point of your line. The Snap Tip also includes a relative polar co-ordinate.

Tips & Tricks

When you are drawing, take a few moments to consider how you will construct each part of the drawing and which Osnaps you will use before starting work. There is always more than one way to draw anything in AutoCAD but the quickest, most accurate and the most efficient way always requires the use of one or more of the Osnap tools.
Dock the Object Snap toolbar to your drawing window for quick access to the Osnaps. You will be using them all the time, one-click access is essential. See Object Snaps to find out how to display the Object Snap toolbar. To dock the toolbar, click on the toolbar title and drag it to the edge of the drawing window.

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