Revit Export to DWG Takes a Long Time

[kevin.sawicki]

Good morning,

Revit takes a very long time to export sheets to DWG files. I am working on a Lenovo ThinkPad P73 laptop with an Intel i7-9750H 2.6GHz processor and 32 GB of RAM. I have several IFC connections, and my Revit file is approximately 150MB. Is there any way to speed up this process, which currently takes hours?

[pkolarik]

Whoa! Hours? How many sheets are you trying to export to dwg? Typically the exports I do are near-instantaneous. I'm usually not exporting 3d views to dwg though, but my model sizes are usually a minimum of 250mb in size (400mb is more typical), so I wouldn't think model size has anything to do with it.

[kevin.sawicki]

I'm trying to export no more than 10 sheets but none of them is exported, even if I left computer for all night. 

My model's weight is ~150MB

I have 8 IFC refferences: architecture, structure, HVACx3, electric, automation and interior.

Do you have any ideas what should I try to fix it?

[curtisridenour]

are you exporting 3D views to DWG?

[hmunsell]

---

@kevin.sawicki wrote:

...I have 8 IFC refferences: architecture, structure, HVACx3, electric, automation and interior.

---

It sounds like you have a full project there. Just curious, why are they all IFC's? Is no one else using Revit?

What export settings are you using?

In the general tab of the export settings is an option to "Export to File Format" i have seen that effect times if it is not the newest format. 

[kevin.sawicki]

The reason why I only have IFC connections is the type of project I am working on. The data exchange format between offices is IFC, and models go through a central information exchange platform. Besides, only one office works in Revit. I believe I have identified the problematic connection, which is the architecture. All other connection configurations do not cause problems during export. The architecture was most likely modeled in Archicad. When importing IFC, Revit creates a file with the RVT extension. I wonder if there was an error in the file conversion. I should add that the architecture is not the heaviest connection in terms of MB.

I am not exporting any 3D views or renderings. I will try to convert the architecture connection to Revit again and check the export settings.

[curtisridenour · Accepted solution]

so you have diagnosed your issue lies within the Archicad IFC? If so, in Revit look very closely at rounded edges within the ARCH content. When i used to work with IFCs Revit really struggled with how revolves and round content was modeled. I had 4 tires per baggage cart and i had 200 baggage carts in a Revit model. When i exported to IFC i noticed that the file size was 80 GB. Eventually i narrowed it down to the baggage cart family and the specifically the wheels. I remodeled the wheels as simple round extrusions instead of complicated revolves. The IFC files were more than 100 times less the size.

All that being said, zoom in on many of the elements of the IFC files and see if you can find lots of triangles of the meshes that make up the elements. If you can identify these elements and simplify/adjust/omit them you might have more success.

[fabiosato · Accepted solution]

Hello,

One problem that may cause your problem is that IFC models are usually represented as meshes, and the number of lines is huge.

I suggest you try to export without displaying the IFC links, trying each one to see which one is problematic.

Usually, we replace the model with a DWG from the corresponding model to avoid this problem.

[kevin.sawicki · Accepted solution]

The problem was resolved by reconnecting and remapping the next revision of architecture IFC file, but the clue pointing to the elements that are repeatedly meshed in the model appears to be correct. 

Thank you for your time.