Join Paul F. Aubin for an in-depth discussion in this video Linking AutoCAD DWG files, part of Revit 2017 Essential Training: Architecture (Metric).
- [Voiceover] It's pretty common to need to access files that were created in other CAD programs in your Revit projects from time to time. The most popular of these, of course, is AutoCAD with its dwg format. One of the most useful ways to access a CAD file is to actually link it into your Revit project. When you link it in, it maintains a connection back to the original file. So, if that file should have to change, then you just simply reload the link to capture those changes. So, let's go over to the Insert tab, and I'll click on the Link CAD button. Now, the files that are supported are dwg, dxf, dgn, and even SketchUp files.
So, I'm gonna leave this set to dwg, and I'm gonna select this AutoCAD Floorplan file right here. Let's talk about some of the settings that we might want to configure when bringing this file in. The first thing that we might want to do is decide what to do about the colors. So, CAD files are in Colors, and you can see it in the Preview window over on the right. If you preserve the colors, they're in those bright primary colors there. They might not look so well on a white background. So, if you want to keep it in color, I recommend choosing Invert instead. Now, Black and White is also an option. So, if you're going to print the file along with your Revit file, you might want to choose Black and White.
Now, you could decide to bring in just the visible layers or specify even. But, in this case, I think All layers is what I want to choose. Revit usually does a pretty good job of automatically figuring out the units in the file. That's what Auto Detect will do. But if for some reason that doesn't work, you can choose a specific unit. I'm gonna leave this checked to Correct the lines that are slightly off axis. That works pretty well for correcting any discrepancies that might occur in round-off errors. Sometimes with really large files, you want to actually uncheck that, and you'll have to do some experimentation to see in which cases that would be.
For positioning, we have lots of options. Origin to Origin is the default. And for this example, I think that'll work just fine. If you don't like where the file comes in using Origin to Origin, you can just simply move it after it's been placed. So, I'll choose Origin to Origin. But before we click open, I want to talk about this Current view only checkbox over on the left. If you leave this unchecked, even though that CAD file is 2D line work, it will be treated in the Revit project as model geometry, like model lines.
And so, any view that you go to, 2D, 3D, it will show that line work. If you check this box, then it will only appear in the current view. It'll treat it like view specific elements in Revit, and it will only appear here in the Level 1 Floor Plan because that's the view that I'm working in. So, in this case, I'm gonna choose Current view only to force it only to display in the current floor plan. I'm inverting the colors, bringing in all the layers, auto-detecting the units, and bringing it in at Origin to Origin. Let me click Open and see what we get.
Notice that it came in kind of in the middle of the screen. The Revit origin is right about here. And so, you can see that the lower left hand corner of the building was where the origin was. Seems to be perfectly logical. If for some reason though you wanted to move it, there are two selection options that you have to make sure are enabled before you'll be able to select this file. So, if you move your mouse around and it doesn't highlight and you're not able to select it, then it could be one of two things that are causing that. If you look down at the lower right hand corner of your screen, there's a series of selection toggle icons.
And this one allows you to select links, and this one allows you to select pinned elements. Now, those same selection toggles are available on this drop-down here beneath the Modify Tool. Select Links, and Select pinned elements. Now, links, of course, is what we have right here. This is a linked CAD file. So, if you uncheck this, you would no longer be able to select this link. And that could be nice to do sometimes if you want to make sure that people don't accidentally move it, for example. Now, pinned kinda serves the same purpose.
And if I uncheck that, I also won't be able to select it. And the reason for that is, I'm gonna turn it back on. When we brought this file in Origin to Origin, Revit automatically pins it. So, again, the idea being that because it's coming in at the origin, you probably want to leave it right there. And all pinned means is you can't move it. So, notice that if I try and drag this, it won't let me move it. So, if I did need to move it, I would unpin it before moving. And I'll undo that to put it back, and then I'll re-pin it.
So, if you want to be able to select this, just make sure that both Select Links and Select pinned elements are enabled. Okay. I'm gonna zoom in on this file. And what I want to do is actually trace over it. There's no command in Revit that's gonna automatically convert your CAD file into Revit geometry. So, your next best thing is to just sort of trace over. Now, I'm gonna go to the Architecture tab, click the Wall command, and I'm gonna choose a generic 300 millimeter wall. Whether or not it's pinned, or not pinned, or selectable, or not selectable doesn't matter, you'll still be able to snap to the geometry in the file.
You can snap to the edges, the intersections, the endpoints, whatever geometry is in there. Notice that if you put your mouse between two parallel lines, Revit will actually sense the two parallel lines and allow you to snap right down the middle of them. And that makes tracing this CAD file really easy to do. Now, I'm gonna go ahead and press Escape one time, change to a different size wall. Maybe this Interior 79 millimeter Partition.
And I'm gonna draw a few more of these. Press Escape again. Zoom in, so I can get a better look here. And notice that I'm not trying to snap these together. And I'm doing that on purpose because I want to clean this up with an Extend command. Now, I'm gonna take this wall and just sort of manually extend that up. And then, I want to show you the Trim and Extend Multiple Elements command. So, the way this command works is you select a single element, and you can pick it anywhere.
Edge or center, it doesn't matter. But I'm gonna select that wall as my boundary edge. Then, any wall that I click will automatically extend or trim to that edge. If you want to reset the boundary, you just click an empty white space. And then, pick a new boundary and keep going. When I click this boundary, I can also use a crossing selection, like so, and select multiple elements at the same time.
The boundary is still active, which means that I could click an additional object and keep going. And once again, if I'm done with that boundary, I'll click an empty space to reset it. Pick a new boundary. Extend these two. And then, if I want to trim this one back again, just click the part you want to keep. So, I want to keep the lower portion and trim the rest away. I'll go to Architecture. Click the Door command. Choose an appropriate size door. Maybe something that's a little bit smaller and start placing it in the locations where it needs to go.
Tap the Space Bar to flip it. And you can see that tracing over the CAD file will move fairly quickly. You can sort of see that the Revit geometry is starting to cover up the color geometry underneath. And that's the reason that I like to bring the CAD file in in color. It just makes it easier for me to tell where the CAD is and where the Revit is. However, if you go to some other view, like a 3D view, spin around, there's all your Revit geometry, but notice there's no CAD geometry here.
That's because we checked that box to say Current view only. Now, I'm gonna go back to the Level 1 Floor Plan. And let's say that the owner of this file has made changes. And so, now, they've saved those changes, and they've informed me that there's been an update. In order to reload a link, you go to the Insert tab and click the Manage Links button. Click on the CAD Formats tab, select your link, and if they just saved over the original file, you just simply reloaded. However, in this case, when they sent me the new file, they changed the name.
So, instead what I'll do is I'll select the file, and I'll choose Reload From. I'm gonna pick this one right here, AutoCAD Floorplan Updated, and I'll click Open. And then, OK. And you'll notice on the left hand side that the wall has moved over. So, if I zoom in a little bit here, notice that the Revit geometry does not automatically update. So, this is important to understand that the CAD file did update underneath, but you're still gonna need to manage your Revit geometry separately. So, I can just simply move that from endpoint to endpoint like so to keep my Revit geometry up to date with the underlying CAD file.
So, linking in a CAD file can be a great way to coordinate efforts from a team that's comprised of Revit users and CAD users. And then, by refreshing the links when changes are made, you can update your Revit geometry accordingly.
First, get comfortable with the Revit environment, and learn to set up a project and add the grids, levels, and dimensions that will anchor your design. Then author Paul F. Aubin helps you dive into modeling: adding walls, doors, and windows; creating and mirroring groups; linking to external assets and DWG files; and working with floors, roofs, and ceilings.
Paul also shows advanced techniques for modeling stairs, complex walls, and partially obscured building elements, as well as adding rooms and solid geometry. Finally, discover how to annotate your drawings so all the components are clearly understood, and learn how to output sheets to DWF, PDF, or AutoCAD.
- Understanding BIM and the Revit element hierarchy
- Navigating views
- Creating a new project from a template
- Adding walls, doors, and windows
- Adding plumbing fixtures and other components
- Linking AutoCAD DWG files
- Rotating and aligning Revit links
- Working with footprint and extrusion roofs
- Adding openings
- Adding railings and extensions to stairs
- Creating stacked and curtain walls
- Hiding and isolating objects
- Adding rooms
- Creating schedule views and tags
- Adding text and dimensions
- Creating new families
- Using reference planes, parameters, and constraints
- Plotting and creating a PDF