How to Create Block Definitions in AutoCAD 2014 - dummies

How to Create Block Definitions in AutoCAD 2014

By Bill Fane, David Byrnes

To create a block definition from objects in the current AutoCAD drawing, use the Block Definition dialog box. (The other way to create a block definition is to insert another drawing file into the current drawing as a block). The following steps show you how to create a block definition by using the Block Definition dialog box:

  1. On the Home tab of the Ribbon, click the Create button on the Block panel, or enter Block and press Enter.

    The Block Definition dialog box appears.


    Pay attention to layers when you create the objects that make up a block. As a rule, block geometry created on most layers retains the color, linetype, lineweight, transparency, and plot style properties of those layers. The exception to the rule is object geometry created on Layer 0. If you create a block on Layer 0, the block takes on the properties of any layer into which you insert it.

  2. Type the block definition’s name in the Name text box.

    If you type the name of an existing block definition, AutoCAD warns you when you click OK at the end of the process. This isn’t always a bad thing because AutoCAD asks whether you want to replace that block definition with the new objects you select.

    This process is known as block redefinition. If you have a drawing with a large number of block insertions such as the bathtubs in a 1,000-room hotel, you can use a simplified block representation during the design process and redefine it to a more complex definition just before final plot time.

    To see a list of the names of all current blocks in the drawing, open the Name drop-down list.

  3. Specify the base point of the block, using either of the following methods:

    • Enter the coordinates of the insertion point in the X, Y, and Z text boxes.

    • Click the Pick Point button and then specify a point on the screen. (In this case, use an object snap or another precision technique to grab a specific point on a block’s object.)

    Use an obvious and consistent point on the group of objects for the base point, such as the lower-left corner or center, so that you know what to expect when you insert the block.

  4. Click the Select Objects button and then select objects to become part of the block.

    AutoCAD uses the selected objects to create a block definition and displays an icon showing those objects next to the block name.


  5. In the Objects area, select a radio button to tell AutoCAD what to do with the objects that are used to define the block: Retain them in place, convert them into a block instance, or delete them.

    The default choice, Convert to Block, is usually the best. See Step 9 for a description of what happens with each choice.

  6. Specify the insert units to which the block will be scaled in the Block Unit drop-down list.

    When you or someone else drags the block from one drawing into another via the DesignCenter palette or Tool Palettes, the units you specify here and the units of the drawing you’re dragging into control the default insertion scale factor. The list contains 17 different units, from angstroms to parsecs, but unfortunately doesn’t include fathoms or furlongs.

    Three additional features in the Block Definition dialog box give you even more control over what happens to blocks as they’re inserted:

    • If the Annotative check box is selected: The block insertion is scaled to suit the current drawing scale, and additional scales can be applied so that the insertion is scaled differently to suit other drawing scales. This would typically be applied only to symbols (such as north arrows) and not to insertions of blocks depicting objects such as toilets or motors.

    • If the Scale Uniformly check box is selected: A block is inserted with the same X, Y, and Z scale factors. (Scale Uniformly is selected automatically if Annotative is selected.)

    • If the Allow Exploding check box is selected: A block can be exploded during or after its insertion in a drawing.

  7. Enter a description of the block in the Description text area.

    You don’t have to enter a description to create a block, but it isn’t a bad idea. Think like a database manager and enter a useful description that identifies the block to yourself and others.

  8. Make sure that the Open in Block Editor check box is deselected.

    You don’t need to use the Edit Block Definition dialog box unless you add dynamic features to the block.

  9. Click OK to complete the block definition process.

    AutoCAD stores the block definition in the current drawing’s block table. This list describes the behavior of the radio buttons you choose from in Step 5:

    • If you select the Convert to Block radio button (the default) in Step 5, AutoCAD creates a block reference pointing to the new block definition. The objects look the same onscreen, but they are now an instance of the block rather than the original, separate objects. Most of the time, this is the best choice.

    • If you select the Retain radio button, the objects remain in place but aren’t converted into a block reference. They remain individual objects with no connection to the new block definition.

    • If you select the Delete radio button, the objects disappear, but the block definition still gets created.

When you define a block, you can include a special kind of variable text object: an attribute definition. When you insert a block that contains one or more attribute definitions, AutoCAD prompts you to fill in values for the text fields. Attributes are useful for elements such as variable title block information, electric motor nameplate information, and symbols that contain different codes or callouts.