# 1 MIN 1 CAD: Excel at CAD Commands Beginning with E

2019-11-29 17:30:43
Dear CAD learners and users, welcome to another article of this series! As usual, I am introducing 5 CAD commands beginning with E in detail. Keep reading and you shall excel at them!

## EDGESURF

EDGESURF (edge-defined surface) serves as a positioning tool. It can help you add planar meshes to a closed entity with four edges. The edges can be arcs, lines, splines, open 2D or 3D polylines. Steps to add meshes:
1. Input [EDGESURF] and press Enter.
2. Select the four edges that form the closed entity one by one.
With the reference axes on the mesh, you can easily locate a point on your entity. Surveyors and landscape designers are bound to find it useful. [su_spoiler title="Tips" open="yes" style="fancy" icon="chevron-circle"]1. The order of your edge selection decides how the mesh will be generated. The first edge determines the M direction, while the two edges connected to the first edge form the N direction. In this case, M and N are used instead of X and Y because the directions of the meshes don’t necessarily correspond with the X- and Y-axes and aren’t necessarily at right angles. 2. Before you invoke EDGESURF, you can adjust the mesh density by changing the values of 2 system variables, “SURFTAB1” or “SURFTAB2”. They respectively control the number of units in the M and N directions. As you can see from the GIF above, I changed them both to 10 and got a 100-unit mesh. The minimum, preset and maximum values are 2, 6 and 32,766 respectively.[/su_spoiler]

## ELLIPSE

You can draw ellipses and elliptical arcs with ELLIPSE. Simple as this command is, some related technical terms might be confusing. Don’t fret! I made the diagram below to illustrate them. As you can see from the image below, the ellipse has two axes of symmetry, the major and minor ones. Steps to draw an ellipse:
1. Input [EL] and press Enter.
2. Specify the first end of one axis.
3. Specify the second end of the axis.
4. Determine one end of the other axis.
To draw an elliptical arc, simply input “A” after the above step 1, repeat the step 2-4 above to draw an ellipse, and cut it to get an arc by specifying the start and end angles. By now you should have a better understanding of what this command can do. [su_spoiler title="Tip" open="yes" style="fancy" icon="chevron-circle"]You can rotate the ellipse around the major axis by inputting “R” and then specifying the angle of rotation after step 3 like I did in the GIF above.[/su_spoiler]

## EXPLODE

EXPLODE enables you to break a compound object into its components in the simplest form. In this way, you can edit the components separately. Speaking of editing, do you remember BEDIT? When I introduced to you CAD commands beginning with B, I explained how to edit blocks with it. However, when you use BEDIT, all blocks with the same name in the same drawing will change correspondingly. If you just want to edit some of the blocks without influencing the others, EXPLODE really comes in handy! Steps:
1. Input [X] and press Enter.
2. Select the to-be-exploded objects.
[su_spoiler title="Tip" open="yes" style="fancy" icon="chevron-circle"]EXPLMODE, a system variable, controls whether NUS blocks (non-uniformly scaled blocks which are not scaled uniformly in X, Y and Z directions) can be exploded. When it is 1, NUS blocks can be exploded, whereas they can’t be exploded when it is 0.[/su_spoiler]

## EXTEND

You can use EXTEND to join the lines. It is especially useful when you’re drawing grids. Steps:
1. Input [EX] and press Enter.
2. Select one or more objects as boundaries and press Enter.
3. Select the to-be-extended objects and then they will be lengthened to the boundary objects specified in step 2.
See? With EXTEND, I can combine all the lines with the grid labels with ease. It provides second chances to you to adjust and fit objects.

## EXTRUDE

This command is similar to EXTEND, but you can use it to create a 3D solid from a surface or a surface from a line in several ways. It will save you a lot of time if you use it to draw walls. Before you invoke this command, make sure that you’ve switched to an oblique view. Steps:
1. Input [EXT] and press Enter.
2. Select the to-be-extruded entities.
3. Specify the height/direction/path/taper angle of extrusion following the prompts in the command line.
As the GIF above shows, I created a surface from a line, a solid from a surface and an extrusion along a specified path. [su_spoiler title="Tips" open="yes" style="fancy" icon="chevron-circle"]1. The system variable, DELOBJ, controls whether to delete the original objects. When it is 1, the original objects are deleted, whereas they are retained when it is 0. 2. The value of the taper angle could be from “-90” to “+90”. When it is positive, the extruded part will be tapered, while when it is negative, the extruded part will be larger than the original entity. If it is 0, the entity will be extended in the direction vertical to the plane where the original entity lies. 3. Blocks and self-intersecting polylines can’t be extruded.[/su_spoiler] What other CAD commands beginning with E do you find “e”fficient? “F”eel free to comment below!
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