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How does CAD constrain drawing

2018-04-18 20:48:13

In CAD drawing, there are a lot of shortcut keys and commands, and for some seemingly difficult to draw graphics, because it is not easy to grasp the direction, Angle, etc. Sometimes difficult to start, and these shortcut keys and commands, but can very well achieve the effect we want, let's take a look at the constraint command drawing.






Open our commonly used software CAD, I am here is the 2010 version, other versions of the operation is basically the same. Look at the menu bar - parameterization - constraint command, there are many kinds, such as vertical, tangent, coincidence and so on can achieve different effects. As shown in the figure


Here we look at one of the vertical commands. Under the line tool of common tools, we draw two lines at will in the figure, as shown in the figure. Select the Parameterization-Vertical constraint command. Here you can see that the mouse has changed into a small square as the selection object.


We select two lines respectively, after selection, the line automatically jumps to the vertical state, as shown in the figure, it should be noted that when choosing a line here, the difference in the selection point will cause the difference in the vertical effect, you can try it.


The operation of other constraint commands is basically the same. Next, we draw a simple combination graph through the combination of tangent, intersection and parallel of different constraint commands. Under the common tools, we draw a big and a small two circles and four lines respectively. For the convenience of operation, we have marked it.


First let's make circles 1 and 2 tangent, and choose parametrically - tangent. Select two circles as objects respectively to achieve the effect of tangent, as shown in the figure.


Next, in the same way we use the tangent constraint command to select circle 1 line 1 tangent - circle 2 line 2 tangent. Through these two steps, line 1 is finally tangent to both circles at the same time. The effect is shown in the figure.


Repeat step 6, we make line 4 tangent to both circles at the same time (if the line is not long enough you can adjust the length of the line and move it etc.). As shown in the figure


The same tangent command makes line 3 tangent to circle 1 and circle 2 tangent to line 4.


Here we see that although they are tangential they do not intersect, and the images are not closed. Here we use the coincidence command. Parameterization - coincidence, select line 1 and line 2; Line 3 overlaps line 4. As shown in the figure


Select the parallel command so that line 2 and line 3 are parallel. After the operation is completed, the following figure is finally drawn by trimming the excess line segment and adjusting the effect such as its rotation. This is widely used in some design drawings at ordinary times.