Monday, December 15, 2014

.DWG's in Revit | Clean Them or Don't Use Them | Ever!!!

The Zen of Clean
Want peace? Use only clean .dwg's (if you must use them at all)... talk to some folks and be told "never use .dwg's" in their projects!!!

[Edit 12/16/2014: If one must use dwg's temporarily (not for generating a topo) then use the "Family Method". Bring the dwg into a family (GenMod(?)) and put that in the project; Revit thinks about them as a Family and acts a bit better... End Edit]

I agree but know that too many people are far too ...ummm...well... lazy to do what's right...

(FWIW: replacing the word 'lazy' in that last sentence with any other word still reads as either lazy or worse) therefore use at your own peril.

Whenever one receives a .dwg file from anyone these processes are requisite prior to any use in Revit.

If these processes are not followed do not, I repeat, DO NOT bring any external .dwg into a Revit Project, if you know what's good for the project.

Is that my opinion?
Yes! BUT it's been verified by so many, with so much evidence of it's necessity that it can safely be deemed fact.

Also understand that the .dwg invariably will have lines not on axis so you may (or are) still bringing garbage that is not just unuseful but damaging to projects, teams and braincells so please don't use them!!! That said, here is a best-case-for-a-worst-case process if you must...

If I forgot any steps please let me know and I'll adjust... Here we go:

Cleaning .dwg Files | Prior to Use in Revit

The following are procedures to accomplish for each and every .dwg (etc.) file prior to linking into or using anywhere in Revit. This will ensure (among other things) that all geometry is within 20 miles from .dwg Origin of 0,0,0.

Notes and Tips:
A)     If, during any of the “Zoom All” commands below, it appears that the screen goes all blank and you do not think you see geometry, think again ;) The geometries are so far apart that entire site (or whatever geometries you have) can appear as only one single pixel… In this case draw a line from 0,0,0 to the top/right of the current view and you should be able to track your geometry for cleaning... which are most likely at that top/right ;)

B)      If any steps are skipped then please expect to do the entire process again!
a.      Verification of the 20 mile limitation is immediate and automatic in Revit
b.      Non-Cleaned .dwg’s are never to be used in a Revit environment
c.       Non-Cleaned .dwg’s create Revit file corruptions especially if over 20 miles from origins... You have been warned!!!

1.       Who is to clean the .dwg?
Either step 1a or step 1b is to be accomplished.
a.       Civil Engineer (for example) cleans their own files | Preferred Method
                                                               i.      Communicate and coordinate this paper and processes with Civil Engineer to have their survey (etc.) be cleaned per below constraints, prior to sharing for Revit use.
b.      Other team cleans copies of Civil .dwg’s
                                                               i.      Save a copy of the original Survey file that is to be used to generate Shared Coordinates.

2.       Preparing the .dwg
a.       Turn all layers on
                                                               i.      Layon

b.      Thaw all layers
                                                               i.      Laythw

c.       Unlock all layers
                                                               i.      Via the layer manager (preferred method)
                                                             ii.      Layulk is sometimes useful for one-of’s

3.       Remove all unnecessary geometry
a.       Top View “Zoom All” (This is distinct from Zoom Extents; Zoom Extents can be told to ignore actual geometry)
                                                               i.      Verify that only the project geometry is on screen; if there is more than project geometry then complete step 3b.
b.      Delete any/all unnecessary geometry (and I mean ALL)
c.       Front View “Zoom All”
                                                               i.      Verify that only the project geometry is on screen; if there is more than project geometry then complete step 3d.
d.      Delete any/all unnecessary geometry (and again, I mean ALL)
4.       Save
5.       Purge All (This may need anywhere from one to four+ passes of purge to get rid of all ‘purgable’ items)

6.       Verify that all unnecessary geometry was truly removed
a.       Top View “Zoom All”
                                                               i.      Verify that only the project geometry is on screen
b.      If any unnecessary geometry exists go back to Step 3b and proceed from there.

c.       Front View “Zoom All”
                                                               i.      Verify that only the project geometry is on screen
d.      If any unnecessary geometry exists go back to Step 3d and proceed from there.

7.       Purge All (an Audit won't hurt either right about now)
a.       Yes purge again and over/over until there are no objects that can be purged.
8.       Save
9.       Close

Now one can use the cleaned .dwg in Revit (if you must)... Cheers!


  1. The autocad command "wblock" could also be usefull when cleaning dwg files.

  2. I have had WBLOCK bring corrupt dwg data across but to each their own ;) Since I like to verify exactly what is going to be used I suggest this more manual approach.

  3. Very good points! Also make sure you take all the dynamic blocks out which have different visibility states.