by Martin Phelps
This function is not new to AutoCAD, but may often be overlooked since it may not be a process often carried out in 2D drawings. It does however assume that the height of the object is constant and therefore is unable to deal with varying heights within the same object, but it can be used to give good volume approximations if the height of the object is not constant.
This simple example comprises of two rectangles, the larger rectangle has base dimensions of 2000 x 2000, and the smaller rectangle has base dimensions of 1000 x 1000, as shown in Figure 1.
Figure 1.
The height of the larger rectangle is 2000 and the height of the smaller rectangle is 1000. The required volume is the subtraction of the smaller value from the larger value.
The “Volume” command is located in the “Measure” fly out menu in the “Utilities” panel of the “Home” tab, as shown in Figure 2.
Figure 2.
As with all AutoCAD commands, the sub commands can be accessed by one of the following methods, right click and select from the displayed menu list as shown in Figure 3.
Figure 3.
Select from the command line, as shown in Figure 4 or type in the capital letter of the sub command displayed in the command line and confirm by pressing enter.
Figure 4.
Note: - the type in option may not always be the initial letter of the command.
Once the “Volume” command has been initialised, the sub command “Add Volume” is selected by one of the methods described above, this will put the command into “Add” mode.
From the sub commands “Object” is activated and the large “Rectangle” selected, which is now temporary infilled in “Green”, the object will lose this colouring once the command have been completed or cancelled, as shown in Figure 5.
Figure 5.
AutoCAD now prompts for the “Height” of the object, as shown in Figure 6.
Figure 6.
The required height can now be typed in, from the information above the height of the large rectangle is 2000, the resulting “Volume” is displayed in the command line as shown in Figure 7.
Figure 7.
Additional closed “Polylines” may be selected and the heights defined for each. The accumulative “Volume” is displayed at the command line.
Once all objects have been selected and the height’s defined, “Enter” is pressed to complete this stage of the command.
To subtract a volume, again using one of the previously described methods above, select the “Subtract Volume” sub command and pick “Object” to select the smaller rectangle, which is displayed with a temporary red background, as shown in Figure 8.
Figure 8.
AutoCAD will again prompt for the height value which is 1000.
The total volume is now displayed in the command Line, as shown in Figure 9.
Figure 9.
Since it is assumed that the drawing units are mm and therefore the resulting volume will be mmᶟ, hence the high value. To convert mmᶟ to mᶟ, multiply the value by , as shown in Figure 10.
Figure 10.
To confirm, Figure 11 shows the simple model constructed as a 3D solid (not available in AutoCAD LT).
Figure 11.
Since this is a “3D Solid” its volume can be obtained by using the “Mass” command. Once the object is selected and confirmed, the “Volume” is displayed in the command line along with additional information, as shown in Figure 12.
Figure 12.