AutoCAD 2014 Precision Procedures
AutoCAD is mostly about being able to draw with precision. Luckily, you’re not on your own here. AutoCAD gives you some help. The following list describes some AutoCAD precision techniques:
Snap: If you turn on Snap mode, AutoCAD constrains the crosshairs to an imaginary rectangular grid of points at the spacing that you’ve specified when AutoCAD prompts you to specify a point.
When you enable Snap mode, at first it seems to be broken because the cursor doesn’t snap to the imaginary grid but travels freely. Snap mode becomes active only when the program asks you to pick a point.
Follow these steps to turn on Snap mode:
Right-click the Snap Mode button on the status bar.
The Snap and Grid tab in the Drafting Settings dialog box appears.
Enter a snap spacing in the Snap X Spacing field and click OK.
Click the Snap Mode button on the status bar, or press F9 to toggle Snap mode off and on.
Usually, you can turn on Snap mode all the time, set at the usual smallest measurement increment.
You can switch between Grid Snap (snap points in rows and columns) and PolarSnap (snap points based on distances and angles) by using the SNAP mode button’s shortcut menu. See the PolarSnap bullet for more information.
Ortho: Using Ortho mode forces the crosshairs to move horizontally or vertically relative to the current coordinate system’s X- and Y-axes. To toggle Ortho mode, click the Ortho Mode button (it’s ORTHO, on text buttons) on the status bar or press F8. Because technical drawings often include lots of orthogonal lines, you may use Ortho mode a lot — but take a close look at polar tracking as well.
Direct distance entry (DDE): This point-and-type technique is an easy and efficient way to draw with precision. You simply point the crosshairs in a particular direction, type a distance value at the command line, and press Enter. You can use DDE at any time the crosshairs are anchored to a point, and the command line or Dynamic Input tooltip prompts you for another point or a distance.
You usually use DDE with polar tracking turned on to specify distances in particular directions. You can also combine DDE with Ortho mode to specify a distance in an orthogonal direction (0, 90, 180, or 270 degrees).
Object snap tracking: This feature extends running object snaps so that you can locate points based on more than one object snap point. For example, you can define a point at the center of a square by tracking to the MIDpoints of two perpendicular sides. Click Object Snap Tracking on the status bar or press F11 to toggle Object Snap Tracking.
You can locate points based on more than one object snap point. Follow these steps:
Draw a rectangle with the RECtang command.
Right-click the OSNAP button, choose Settings, turn on MIDpoint, and then click OK.
Make sure OSNAP and OTRACK are turned on.
Start the Circle command.
Move the cursor close to the middle of the bottom line of the rectangle until the green triangle osnap marker appears. Don’t pick this point.
Move the cursor vertically and note that the green triangle disappears to be replaced by a green + sign, and a vertical dotted green line appears.
Move the cursor close to the middle of one of the vertical lines of the rectangle until the green triangle osnap marker appears. Don’t pick this point either.
Move the cursor horizontally until the two dotted green lines cross and an X appears, along with a midpoint tooltip.
Click this point to define the center of a circle that is exactly in the middle of the rectangle.
You can use this same technique to transfer points from a front view to a top view or to a side view without having to use construction lines.
Polar tracking: When you turn on polar tracking, the crosshairs jump to increments of the angle you specified in the Drafting Settings dialog box or chose on the right-click menu. When the crosshairs jump, a tooltip label starting with Polar: appears. Right-click the Polar Tracking button on the status bar and choose the Settings option to display the Polar Tracking tab in the Drafting Settings dialog box.
Select an angle from the Increment Angle drop-down list and then click OK. Click the Polar Tracking button on the status bar or press F10 to toggle Polar Tracking mode.
Polar and Ortho modes are mutually exclusive. Turning on one turns off the other.
PolarSnap: You can force polar tracking to jump to specific incremental distances by changing the snap type from Grid snap to PolarSnap. For example, if you turn on polar tracking and set it to 45 degrees, and turn on PolarSnap and set it to 2 units, polar tracking jumps to points that are at angle increments of 45 degrees and distance increments of 2 units from the previous point.
To activate PolarSnap, right-click the Snap Mode button and choose PolarSnap from the menu. To specify a PolarSnap distance, follow these steps:
Right-click the SNAP button on the status bar.
The Snap and Grid tab on the Drafting Settings dialog box appears.
Click the PolarSnap radio button, type a distance in the Polar Distance text box, and then click OK.
When you want to return to ordinary rectangular snap, right-click the Snap Mode button and choose Grid Snap from the menu.
Temporary override: Settings such as Snap, Ortho, and Polar remain on until you turn them off. You can also use a temporary override, which lasts only as long as you hold down its key or key combination. For example, when Ortho mode is turned off, holding down the Shift key puts AutoCAD into Ortho mode temporarily for as long as you press Shift.