My imported CAD file doesn't join with the ground plane properly

[eric-s]

1. Flatten Linework
I would start over without the ground plane underneath. Then flatten using what others suggested or, like me, try: Flatten to Plane.

Then make sure all of your edges are closed and no gaps appear. This is not possible to do by eyeballing it alone. SketchUp converts CAD vector arcs to segmented arcs so that opens up a lot of room for error and little gaps or overhangs in linework to appear.

2. Close Gaps
To close those gaps, I use Edge Tools. You can select all the linework at once, or just the part that’s giving you trouble then choose ‘Close edge gaps’ from the Tools/Edge Tools drop down. Set a small number for the distance and it should close them.

3. Make Faces
Then use Face Creator, or something similar to automatically make faces. This should work nearly every time assuming your CAD linework is as cleanly drafted as it can be.

Let me know if you have any trouble. I don’t have time to add an animated gif at the moment but can do if needed. Good luck.

[DaveR]

Having been sent the file via PM, I was able to see that the imported line work does not lie on the ground plane.

As I wrote previously…

@DaveR

If you are checking for flat, set units to millimeters or inches and precision as high as it will go. It doesn’t take much off plane to cause this problem and you aren’t likely to see it with coarser units or low precision. Also check the endpoints around the oval to make sure their Z values are the same.

FWIW I purged unused stuff from your file. There was a lot. Purging the unused stuff reduced the file size by almost 98%.

[Anssi]

A simple way to flatten things is to go to top view, select Parallel Projection and export a 2D image as a DWG file to full scale, and re-import that.

[Bxsaldana]

I really want to thank ALL of you guys for your help. Each tip I saved in my “toolbox” now and learned a ton. You guys are great.

[jobyna.b.mcgee]

I am doing that now and have been working my floor plan in AutoCAD. For me, it is easier for space planning, dimensions and thinking through my design. Yes, if you just bring a CAD drawing into your Sketchup model it comes in weird. So I set up an outline, a rectangle the size of my floor plan in sketchup and then use it to anchor my existing CAD to it as a work surface. I do that on a Sketchup layer dedicated to that purpose. Which let’s me hide it whenever I want to. Good planning at that level keeps your models clean. However, before you import things to SU, you need to set up your CAD drawing first. I make layers and sort objects into groups, but not blocks, When I start working in Sketchup, I use more new layers It will let me do that in 2018 pro. It also helps to verify that the scale of what I am importing is equal.