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IntermediateFree AutoCAD course about 22 min

Blocks: reusable symbols

A block is a named group of objects you draw once and place many times — doors, windows, furniture, symbols, title blocks. Edit the definition and every copy updates.

In this lesson you will

  • Create blocks with sensible insertion points
  • Insert, rotate and scale blocks
  • Edit blocks with BEDIT and redefine them
  • Add attributes and build a block library

Definitions and references

When you create a block, AutoCAD stores a block definition in the drawing. Each placement is a block reference pointing to that definition. A hundred door references cost almost nothing in file size, and editing the definition updates all hundred at once.

A door block definition with its insertion point marked at the hinge. Three references of the same block are placed in a plan at different positions and rotations; editing the definition updates all three.Definitioninsertion pointDOOR-820References in the planedit the definition once → all references update
Figure: One block definition, many references. Original KitWren diagram.

Creating a block

  1. 1Draw the symbol full size — e.g. an 820 door leaf and swing — on layer 0 with colour, linetype and lineweight ByBlock or ByLayer.
  2. 2Type B (BLOCK). Name it clearly, e.g. DOOR-820.
  3. 3Pick the base point — the insertion point. For a door, the hinge corner; for furniture, a logical corner.
  4. 4Select the objects. Choose Convert to block to replace them with a reference.
  5. 5Set Block unit to your drawing unit so it scales correctly when inserted elsewhere.

Objects on layer 0 inside a block take on the layer of the reference, so a door block placed on A-DOOR looks and prints like A-DOOR.

Inserting blocks

I (INSERT) opens the Blocks palette: choose the block, then pick the insertion point, rotation and scale. The palette's Recent and Libraries tabs let you insert blocks from other drawings too. Blocks can also be dragged from Tool Palettes and DesignCenter (ADC).

Editing and redefining

Double-click a reference or type BE (BEDIT) to open the Block Editor. Change the geometry, click Save Block and close — every reference updates. REFEDIT edits in place within the drawing.

EXPLODE turns one reference back into loose objects — avoid it; exploded blocks lose all the benefits.

Attributes

Attributes are text fields inside a block that change per reference: a door number, a room name and area on a room tag, the drawing number in a title block. Define them with ATT (ATTDEF) inside the block, then fill them in on insertion; edit with a double-click (EATTEDIT). Attribute data can be extracted to a table with DATAEXTRACTION — the start of automatic schedules.

A block library

Save each standard block as its own drawing with W (WBLOCK), in a shared Blocks folder. Everyone then inserts the same doors, symbols and title blocks, which keeps drawings consistent across a team.

Quick reference

Command / toolHow to start itWhat it does
BLOCKBCreates a block definition
INSERTIBlocks palette / insert
BEDITBEBlock Editor
WBLOCKWWrites a block to its own file
ATTDEFATTDefines an attribute
PURGEPURemoves unused block definitions

Common mistakes

  • Block has a far-away insertion point and jumps when inserted.

    Redefine with the base point on the object (BEDIT › Basepoint parameter or re-create).

  • Block keeps its own colours whatever layer it's on.

    Build it on layer 0 with ByLayer/ByBlock properties.

  • Exploding blocks to edit one.

    Use BEDIT; if one variation is needed, make a new block or use a dynamic block.

Exercise

Door, window and room tag blocks

  1. Create DOOR-820 with its insertion point at the hinge.
  2. Create WIN-1200 (a 1200 window in a 230 wall) with a centre insertion point.
  3. Create a room tag block with attributes NAME and AREA.
  4. Insert doors and windows into your plan, rotating as needed.
  5. Edit DOOR-820 in the Block Editor to add a door stop line and watch every door update.
  6. WBLOCK your blocks into a Blocks folder.

You should end up with: A small reusable block library and a plan that uses it.

Checklist

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Lesson quiz

1 / 5

Editing a block definition updates every reference of that block.

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Questions

Where can I get AutoCAD blocks?

Build your own from manufacturers' published dimensions, use the sample blocks that ship with AutoCAD, or download from manufacturers' official websites. Check the licence for any block library you download, and avoid unknown sites that bundle unlicensed content.

Free, independent learning material written for KitWren. AutoCAD and AutoCAD LT are registered trademarks of Autodesk, Inc. KitWren is not affiliated with, sponsored or endorsed by Autodesk. We never provide software downloads, licence keys or cracks — use the official sources.