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REFERENCE feature in SCALE and ROTATE

10 Comments Nov-07-2007 | Posted by Erhan Toker | Printable Version | Level |

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For those who use ROTATE and SCALE commands, I will explain a very important feature that exists in these commands. By using this feature, it will be possible to bring an entity to a specified angle, or to bring a line, which has unknown length, to a specified length. This feature is called REFERENCE. Now, let’s briefly explain this feature:

Fig. 1.

Let’s start with drawing the line with a length of approximately 398.55 and an inclination of 32 degrees. Draw roughly. We are already trying to put in order a roughly prepared drawing. Let’s try both of the commands on this line. First of all, let’s make the length of the line 500 by SCALE command;

Command : SCALE
Select objects: ( select the line )
Specify base point: ( select the lower left corner of the line )
Specify scale factor or [ Copy/ Reference]: R ( Here, we are selecting REFERENCE with R)
Specify the reference length : (At this point, let’s select the both ends of the line and determine its length )
Specify the new length or [Points]: 500 ( press ENTER)

If you measure by DISTANCE command, you will see that the length is exactly 500 units. Here the important part is to show the two end points of the line while entering the reference length. ROTATE command also works in the same manner. Only difference is that, in this command reference angle is required, not he reference length. At this point, it is important to choose which end of the line first. The reason is that, if you change the selection points one for another, reference angle will change by 180 degrees.

Command : ROTATE
Select objects: (select the line)
Specify base point: ( select the lower left corner of the line )
Specify rotation angle or [ Copy/ Reference] <0>: R (Here, we are selecting REFERENCE with R)
Specify the reference angle : (At this point, let’s select the both ends of the line and determine its angle )
Specify the new angle or [Points]: 0 ( press ENTER )

Fig. 2.

While selecting the point to show the reference angle, the important point is that first selected point must be the same as the BASE POINT. By this way, cursor is locked on the entity to be rotated (Fig. 2).

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