At Autodesk University 2024, I delivered a session on Working Smartly with Blocks in AutoCAD. An attendee asked about the differences between Replace and Block Replace. This is an excellent question. However, it was asked in the survey, so I am unable to respond, nor do I know who asked the question. So here is the answer!
FIND (and REPLACE)
FIND is not specific to AutoCAD. It is a tool in most word processors and text editors. Use it to quickly locate text by searching for words and phrases. It is useful for navigating a document and for checking for the presence of specific words.
Think of Find as a search engine for your document. In AutoCAD, use it to locate words in text, attributes, dimensions, leaders, tables, and hyperlinks.
Replace extends find so that is also replaces the found text. Replacement is content only; it leaves the existing character and paragraph formatting unchanged.
BLOCKREPLACE (Express Tool)
As there is no actual REPLACE command in AutoCAD, and Find and Replace works with text, I am assuming the attendee meant BLOCKREPLACE. This is an Express Tool command.
Finding all the blocks in a drawing to replace can be a tedious process. So, BLOCKREPLACE makes this easier by replacing all instances of a block with a different block definition.
The first step is specifying the block definition for replacement. Do this by selecting it in the dialog or by picking an instance within the active drawing.
Then select the replacement block, again either by selecting it in the dialog or by picking it within the drawing.
AutoCAD prompts you to purge the now unreferenced block definition from the drawing. If you choose not to purge the unreferenced block definition, you can always use the purge function later.
The command searches the entire drawing for the specified block, replacing it with a block that you specify. The replaced block inserts with the same scale, insertion point, and rotation as the existing instance.
Heads up that BLOCKREPLACE has a commandline-only version (-BLOCKREPLACE) if needing to do scripting or similar automation.
Similar is BLOCKTOXREF, which replaces a block definition (and all instances) with a selected xref.
Block Replace (BREPLACE)
Block Replace (BREPLACE) is a smart block feature. It replaces selected block instances with a selected block.
Unlike BLOCKREPLACE, BREPLACE does not replace all instances. Instead, it only replaces the instances you select.
After starting the command, select the blocks. Note, they must all be of the same definition.
From the Block Replacement panel, select the desired replacement. AutoCAD uses machine learning to generate suggestions. This capitalizes on the block name and visual similarity between existing blocks. The suggestions are based on the available block definitions in the drawing and your block libraries.
So with BREPLACE, you can choose between the suggestions, recently used blocks, or pick the replacement from the drawing. The replaced block instance retains the scale, rotation, and attribute values of the original block.
BLOCKREPLACE vs BREPLACE
BLOCKREPLACE is quicker and cleaner when wanting to replace all instances of a block in a drawing. It can be simple to miss instances with BREPLACE, especially if on off/frozen layers or in different spaces. BLOCKREPLACE even purges the original definition, cleaning the drawing as it goes.
BREPLACE, however, gives the flexibility of replacing only selected instances. So you would use BLOCKREPLACE when wanting to replace all instances and BREPLACE when wanting to replace only selected instances.
The benefit of BREPLACE is not needing to know the replacement block ahead of time, as AutoCAD smartly suggests blocks similar in geometry and orientation. You can also select from recently used blocks, even if those blocks were recently used in other drawings.
As BREPLACE lists blocks not only from the current drawing but also the block libraries, it can save time by not needing to first add the block definition to the drawing.
---
Want to learn more about BREPLACE and the other Smart Block features? Check out my AU class.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.