The Risks Of Copying and Pasting Blocks

Why Do My Blocks Look Different From Drawing To Drawing?

There is one reason really:
The block was already in your drawing and the block has been edited.

The Problem
It is ironic that we create block libraries to develop continuity in our drawings, but because they can be edited, they are one of the items that can cause a lot of problems. The more a block is edited, the higher probability you have some sort of block problem with your drawings (especially if you are collaborating with people within the office). This problem will manifest itself when copying and pasting blocks from one drawing to another.

Block Characteristics
Blocks have this distinct characteristic, "the first block there wins", and by that I mean if an edited block is in the drawing before the standard block, the standard block will look like the edited block. Inserting a block from a palette, pull down menu, or dialog box will not always insert the most current and up-to-date block from the block library. It will only be the most current and up-to-date block, if that block has not been inserted before. If the block has already been placed in that drawing, AutoCAD will continue to use the block already stored in the drawing.

Common Scenario
One of the most common scenarios, is the copying and pasting of plant blocks from one drawing to another. Which block you will see? It all depends on which block was there first (shown below).

A.) The edited block has been turned green
B.) The standard block on the right has been copied.
C.) The standard block has been pasted into the drawing with the edited block. Notice that the standard block now looks like the edited block.

Color is not the only item that can be changed. Changing the scale, insert units, and attributes are all quite common issues as well.

Fixing A Standard Block
To fix a standard block back to the original, use the Update Block command (TBG shortcut "UB"). If the name of the block is the same as the one in our standard library, update block will change all the blocks with that name in the drawing to the original standard block.

Please be aware....
Some blocks may have different insert points (due to editing) and may not appear in the same place. A good example would be updating our "older" spot grade symbol to the "newer" spot grade. They have different insert points. If this happens, just use the undo command to put them back the way they were.