How-to guide · how to set a block to not be exploded
How to set a block so it cannot be exploded in AutoCAD
By Saumyajit Maity · Published 17 Jul 2022 · Updated 6 Jun 2024
Exploding a block breaks it back into its raw lines, arcs and text, destroying the block reference. Usually that is useful, but sometimes you want the opposite: a block that colleagues cannot accidentally blow apart — a standard detail, a manufacturer's component, a title block, or any geometry that must stay intact as a managed unit. AutoCAD lets you mark a block definition as non-explodable so the EXPLODE command simply refuses to act on it.
This is a single property on the block definition, set when you create the block or edited afterwards, and it travels with the block wherever it is inserted. It is a light-touch protection: it stops the everyday accident of selecting everything, hitting Explode, and shattering a carefully built block, without locking the drawing down.
This guide sets the Allow exploding property correctly, shows where to find it on existing blocks, and explains what the setting does and does not protect against — because non-explodable is about keeping a block whole, not about security.
Step 1 — Understand what 'Allow exploding' controls
Every block definition has an Allow exploding property. When it is on (the default), users can run EXPLODE on the block to break it into its component objects. When it is off, EXPLODE refuses and the block stays whole. The setting lives on the definition, so it applies to every instance of that block in the drawing.
This is the cleanest way to keep a block intact. Rather than relying on people not to explode your standard details, you simply remove the ability to do so. The block still inserts, moves, copies and scales normally — only the destructive explode is blocked.
Step 2 — Set it when you create the block
When you define a block with the BLOCK command, the Block Definition dialog has a Behavior group containing an Allow exploding checkbox. Untick it before you click OK, and the new block is created as non-explodable from the start. This is the tidiest moment to set it, because the property is baked in as the block is born.
While you are in that Behavior group, you will also see Annotative and Scale uniformly options — Allow exploding sits right alongside them. For a standard component or detail you are publishing for others to use, unticking Allow exploding at creation time is good practice.
Step 3 — Change it on an existing block
For a block that already exists, you can edit the property without recreating it. Open the Block Editor with BEDIT, select the block name, and in the Block Editor's settings (or the block's Properties) set Allow exploding to No, then save. Alternatively, redefine the block via the Block Definition dialog with the checkbox unticked.
The change applies to the definition, so once saved, no instance of that block can be exploded — including ones already placed in the drawing. There is no need to re-insert anything; the existing references inherit the updated rule the moment the definition is saved.
Step 4 — Test that explode is blocked
Insert or select an instance of the block and run EXPLODE on it. With Allow exploding off, AutoCAD reports that the object cannot be exploded and leaves the block intact. That refusal is the confirmation that the property is set correctly.
If the block still explodes, the change was not saved into the definition, or you edited a different block of a similar name. Re-open the Block Editor, confirm Allow exploding reads No on the right block, and save again. A quick explode test is the only reliable way to know the protection is live.
Step 5 — Know what it does and does not protect
A non-explodable block is protected against the EXPLODE command, which is the everyday way blocks get broken apart by mistake. It is not a security feature: someone determined can still open the Block Editor and edit the definition, redefine the block, or change the Allow exploding setting back. Treat it as a guard against accidents, not a lock against intent.
It also does not stop the block being deleted, moved or scaled — only exploded. If you also want to prevent moving or editing, combine non-explodable with a locked layer. For most uses, though, simply preventing accidental explode is exactly the right level of protection for standard details and supplied components.
Pitfalls when setting blocks non-explodable
The first pitfall is forgetting that the setting is on the definition, not the instance — you cannot make one copy explodable and another not; they share the definition's rule. If you need both behaviours, you need two block definitions.
The second is editing the wrong block when several have similar names; always confirm the name in the Block Editor before saving. A third is assuming non-explodable means tamper-proof — it does not, because the definition can still be edited or redefined by anyone with the Block Editor. Finally, do not set every block non-explodable out of habit; for working geometry that people legitimately need to break apart, leaving explode enabled is kinder. Reserve the setting for standard details, components and title blocks that should stay whole.
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Questions
Frequently asked
Where is the setting to stop a block being exploded?+
It is the Allow exploding checkbox in the Behavior group of the Block Definition dialog when you create a block, or the Allow exploding property in the Block Editor for an existing block. Turn it off to block exploding.
Does making a block non-explodable affect copies already in the drawing?+
Yes. The setting lives on the block definition, so once you save it as non-explodable, every existing instance of that block can no longer be exploded — no re-inserting is needed.
Can I make one copy of a block explodable and another not?+
No. Allow exploding is a property of the definition, which all instances share. If you need both behaviours, create two separate block definitions with different settings.
Is a non-explodable block tamper-proof?+
No. It guards against the accidental EXPLODE command, but anyone can still open the Block Editor and redefine the block or re-enable exploding. It is accident protection, not security.
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