Cleaning up architects .dwg plans

I have to use some .dwg drawings made by an architect. They contain an immense amount of information i do not need. I deleted part of the drawing but cannot delete the layers that belong to that part of the drawing. I keeps saying i cannot delete layers with block son them. When i want to deleten blocks in the block manager i get the message: unable to delete nested blocks.
I selected all block instances and exploded them but it keeps telling me there are still block definitions on layers that i want to delete.
How can i get rid of all this useless information?

Regards, René

Use the purge command to get rid of unused block definitions.

THat does not work for me. The objects are still in my scene. I just want to unblock them. A special problem are the nested blocks which i can only get rid of through the blockmanager. Block by block as it seems. A very timeconsuming process where i do not want to go into.
I also cannot get rid of layers with objrcvtsd i do not want. Because of the blocks and nested blocks.
Well i guess it is just one of those things i have to learn to live with.

Regards, rene

instead of getting rid of what you don’t want can you paste what you do in to a new document?

Not 100% sure exactly what you have of course, but does SelBlockinstance followed by ExplodeBlock, followed by Purge get you closer?
Note that you’ll have to double check that the commands are correct - I’m not on a PC at the moment.

This doesn’t really answer your question, but since I’m working with horribly complicated architects drawings (why do they do that?) every day here’s what I do.

I don’t get rid of anything. Depending on what you’re doing, that thing you just got rid of might have a significance later on.

I move all the architect’s layers into a new layer so that I can turn the architect’s drawing on and off at a click. It’s mostly off because as you say, the drawings are very complicated and that makes working on top of them difficult.


use blockmanager,…

I know. That is what i also do now, everything in one layer. I just want to get rid of everything i do not need to keep a clean and simple file and i do agree with your comment on architect drawings. Very complicated and with layernames that are beyond my reach of understanding.

vriendelijke groet, René van Corven

atelier van corven logo paars

Atelier van Corven

Celebesstraat 1

6707 ED Wageningen

Tel: 06 26 552555

Van: John Hesp []

Verzonden: zaterdag 8 november 2014 8:35


Onderwerp: [McNeel Forum] [Rhino for Windows] Cleaning up architects .dwg plans


November 8

This doesn't really answer your question, but since I'm working with horribly complicated architects drawings (why do they do that?) every day here's what I do.

I don't get rid of anything. Depending on what you're doing, that thing you just got rid of might have a significance later on.

I move all the architect's layers into a new layer so that I can turn the architect's drawing on and off at a click. It's mostly off because as you say, the drawings are very complicated and that makes working on top of them difficult.


To respond, reply to this email or visit in your browser.

To unsubscribe from these emails, visit your user preferences.

You can also try ExplodeBlock>AllBlocks - which will explode all nested blocks into real geometry. Then you should be able to purge the unused block definitions with block manager.

Beware though, if the drawings include things like trees, etc. those can explode into thousands of objects…


(not saying this is THE solution… it’s just what i do)

i generally need only the floor plan so i’ll just redraw it… if you only need portions of the info, it’s often faster than trying to figure out what everything else is and mange it… plus, you’re reassured it’s drawn to your liking as well as check for bad dimensions, pesky little line breaks, etc…

I do what Jeff does but that is mainly because I am not creating 2d documentation usually it’s better to generate the 3d model from native Rhino line work. Dwgs usually contain line work that is blocked or just not suitable for 3d work.

What I do is move and or edit the dwg contents where I want it in space if needed. Save that file as a rhino 3d file, close that file.

Open a new Rhino file, then open the work-session dialog box from the file menu and click attach, place the previously saved file as a template for the 3d linework you plan to draw, this way you can attach any amount of dwg files and use them for reference, turn them on and off easily and even create things with their linework if the lines are acceptable.

Sometimes I insert the dwgs as blocks so that if I get an updated file from the architect I can update the plan easily, When history gets better for V6 I can hopefully reference the block update and the 3d model will update automatically.

Note I usually save the dwg file as a Rhino file first before work-session attachment. Above I’m referring to dwg files saved as Rhino files, though you could also attach dwg files directly in a worksession or placed as blocks.

Roland M

I guess there are, contrary to general opinion, some constants in life:
I always want to accept the architect’s drawings as is and use them
I always end up redrawing them

I think dealing with blocks and other data is better done on the AutoCAD (or similar) side of the equation. Select all the geometry you want then copy it into a new drawing file. Mothball the original.

I find Overkill to be a real useful command when dealing with architect’s dwgs and I wish we had similar in Rhino. If you’re not familiar with it - select an area or the whole drawing and run overkill and it will search out any duplicated lines or overlapping lines and kill them. I ran that command today on a dwg someone sent me and it reported over 800 duplicated lines removed.

Yeah, for awhile Rhino was way ahead when it had SelDup and ACAD didn’t… Unfortunately, there has been no new development in this area since then on the Rhino end… Now I have students asking me “where is the Overkill command in Rhino?”


Hi Rene,
This is what we have been using successfully with rhino files (in Rhino 5):

purge (optional)
EXPLODE (the still selected blocks to get rid of nested blocks)
PURGE ( check that block definition = yes)
CLOSE (& save) and REOPEN your file to get rid of block references
now you can DELETE those layers that used to tell you they had block definitions on them
JOIN to reconnect all those curves

Let me know if this is useful

Like arail, I trace over all imported geometry. While this would appear to be inefficient and slow, it isn’t when you consider all the work needed to make the imported geometry usable.

I found that inserting a complex .dwg as a reference in Rhino helps keeps things more manageable. It creates a layer with the imported dwg name and all the dwg layers are sublayers beneath the main layer. Now if only Rhino had OFF or FREEZE layer by hit!

1 Like

Hi Lifetime…

You saved lifetime, so i had to log me in because I´m so amazed right now.
your Workflow did change loading time von 27minutes to 1sek… it is, as most of the time, acad block ref´s. this 1sek… lets say its 2 sek´s , but thats not it.

this file is then referenzed as underlay into several other files. in these files there is a lot of 3D geometry, complex… this did come together in ultralong loading times… handling of these files was like swimming through dry mud…

now everything is fine, flow in rhino is back… love it…


Hi Rene - as Mitch mentioned above, you can use ExplodeBlock to take care of all nested blocks in one shot, rather than multiple Explodes.


Thanks pol1
Glad to hear this has been useful😀