Symbols: Creating

Nothing Special

In one sense there is nothing special about the data that goes into a block. You just use the program in the usual way, creating lines or geometry. Then you select some of it and issue a command to "make this stuff into a block named X". The program copies those lines or geometry into a special (not displayed) storage area. Then you issue another command to "place an instance of X here" to use the block. That's the basic operation.

Blocks and File Size

One of the main reasons blocks are useful is that one definition (which might be big) can be used to draw many many instances (which are small), which makes the file smaller, quicker to load, etc.

Using a Model as a Block

ANY existing model or drawing can be added to another model or drawing as a block in the second file. The original model's ORIGIN automatically becomes the BLOCK insertion point. In Rhino this is done with "File > Insert ...".

Things to Think About

Scale

When you insert a block instance you set a scale factor for that instance. This suggests two scale-related strategies: full-sized objects that are created using their actual dimensions (manufactured objects like particular models of desk or toilet), and unit-size objects like tree symbols or generic bits of geometry (schematic doors) which might be resized when used. Making a unit sized object (fits in a unit square) makes it easy to calculate a scale factor.

Insertion Point

The lower-left-corner of the object might not be the most useful "handle" by which to insert or rotate it. The center of a tree makes more sense, as does the center-line of a toilet. The point might not even be ON the object—an insertion point can be snapped to a wall and used to offset the object a standard distance from the wall.

Name

Meaningful names that fit some sort of a naming convention (offices often set some rules) make symbols that are more useful to more people. Don't name them "block1".

Layers, Colors, & Linestyles

Make sure you review the page about "attributes". You might not understand all the variations right away, but these can prove useful.

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