Rhino Not responding after calling Purge command


I have an issue, which may not necessarily be caused by Rhino, but nevertheless any kind of help would very appreciated.

I have a DWG which a client exported from Revit. The DWG is about 680 MB in size.

I opened that DWG in Rhino 6 SR35 and started deleting certain geometry. After this, I would like to purge all block definitions from deleted block instances.
However, _Purge command never ends even after 24 hours, and I just get “Not responding”.

I assume the reason may be too large number of block definitions, and some of them may be nested. When I saved the upper Rhino file its filesize is 2 GB.

Maybe you have any kind of advice how to purge all those unused block definitions? This will massively decrease the Rhino file size.

As a last hope, I tried calling the doc.InstanceDefinitions.Compact(True) in order to Purge via API. Then after this call, I saved the Rhino file, but the filesize is still 2GB, which means no block definitions have been purged. (also, I see from the upper link that this issue with purging block definitions via API is still present.)

At this point, any suggestion or help is welcomed.

Hi @djordje,

Free free to pm me the file. If you need help with big files, use our file uploader, attn: dale@mcneel.com.


– Dale

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If you deleted or exploded all the blocks, so only definitions are left, you may try to select everything, and export selected to a new file.
The unused block definitions should not carry over.
(I remember having to wait for Purge to complete forever on such files, it eventually ends but may be very slow as you mentioned).



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Hi @Jarek ,
I still have plenty of block instances left, which I don’t intend to delete.
But you gave me a very good suggestion. I will try it, thank you.

@Jarek your suggestion worked perfectly! Selected all, then File->Export Selected and saved as a new .3dm file. The 3dm filesize is now 800MB, and Purge works without issues. Thank you for the solution!

@dale thank you also for offering to help!

Great, I’m glad it worked. Perhaps there is something that can be done ‘under the hood’ of Rhino for purge not to get stuck on these files @dale . This is pretty common when you import Revit file via CAD format, that each of the elements is its own block definition, even if they are the same or could be just scaled versions of the same block definition. So you end up with 1000s of block definitions at first, and any attempt of purging results in this situation, unless you use the above workaround.

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Hi @Jarek,

Without a file, no chance.

— Dale

@djordje - maybe it’s still worth sharing the sample file with long purge with Dale in case some improvements can be made to the Purge command speed in future. I don’t have anything handy right now.

Hi @Jarek ,
I can ask, as the file belongs to a company.

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