SMARTBURST explodes blocks while keeping their attribute values as text — a better behaved replacement for the Express Tools BURST command. SMARTBURSTALL does the same and follows nesting to any depth.
What SmartBurst does
Five things it fixes about Express BURST, each of which is a real defect rather than a preference:
Invisible attributes stay invisible. Express BURST reveals attributes the block author deliberately hid, splattering internal data across the drawing. Both the attribute’s own invisible flag and its Visible property are checked here.
Visible constant attributes are kept. Express BURST discards them, losing annotation that was plainly on screen a moment earlier. Constant attributes exist as definitions rather than instances, so they need handling separately — which is what the attribute-definition branch does.
Hidden dynamic block geometry is removed. Exploding a dynamic block produces the geometry of every visibility state, not just the one on display. Anything coming back invisible is deleted rather than dumped into the drawing.
Attribute transparency survives — DXF group 440 carries it and is preserved through the conversion.
BYBLOCK properties are resolved. Objects drawn on layer 0, or with BYBLOCK colour or linetype, inherit from the block reference — which ceases to exist once burst. Their inherited values are written onto them first, so the drawing looks identical afterwards.
How to use it
- Load the routine with
APPLOAD, or put it on your support file search path. - Type
SMARTBURSTfor the selected blocks only, orSMARTBURSTALLto follow nesting all the way down. - Select the blocks. Xrefs cannot be selected.
How it works
Xrefs are excluded at both levels: the selection filter removes xref definitions, and the recursive pass skips anything with a Path property. An xref cannot be exploded, and catching it in only one of those two places is how a recursive burst ends up failing part way through a set.
There is a documented entry point for your own code. SmartBurst:Selection takes a selection set and a nested flag, so it can be called directly from other routines rather than having to drive the command.
Notes and limits
- Hidden attributes stay hidden and hidden dynamic geometry is removed — the two things that make Express BURST messy.
- Bursting is effectively one-way. One undo puts it back; once you carry on working, rebuilding the block is manual.
- Xrefs are excluded at selection and during recursion.
- Dynamic blocks burst to their displayed state, which is what you can see.
Download and details
| Name | SmartBurst — explode blocks while keeping attribute values as text |
| Download | SmartBurst.lsp — 17.7 KB, plain AutoLISP source. Downloads directly; no zip to unpack. |
| Type | AutoCAD AutoLISP routine |
| Commands | SMARTBURST, SMARTBURSTALL |
| Requires | the ActiveX layer (loaded automatically by the routine with vl-load-com). |
| Source size | 17.7 KB, 430 lines |
| Error handling | Yes — a *error* handler restores every system variable it changed, on cancel as well as on error. |
| Undo | The whole operation is wrapped in a single undo group, so one U reverses all of it. |
| Compatibility | AutoCAD (any release with AutoLISP), BricsCAD, ZWCAD, GstarCAD, ProgeCAD and other IntelliCAD-based platforms. AutoCAD LT needs a LISP enabler. No .NET, no ObjectARX, no installer. |
| Author | YZ, August 2026 |
| Licence | Free to use, supplied “as is” with no warranty. |
References
- DEEPBURST LISP — the same job through every nesting level in one pass
- BLOCKPROMOTE LISP — extract one nested block instead of bursting everything
- ATTCLONE LISP — match attribute formatting before you burst
- More free AutoLISP routines on this site
- Wisey’s Steel Shapes — free structural steel section drawing program