Exporting 3d ojects as STLs

[Shea_G]

Sometimes when I export a solid as a stl it comes out very blocky and misshapen, and others it works perfectly fine and I cannot pinpoint when it will work right and when it wont. See both screenshots taken of the exact same file. Please help me, i'm at my wits end

[S.Faris]

Try Increasing the FACETRES Value as Explained here 

[Shea_G]

I tried that already, doesn't make any difference. When I try to use surfsculpt I get the error "Solid creation failed, no watertight volume detected."

The weird thing is when I create a box, using the box command, I get the exact same error.

Im using civil3d if that makes any difference.

[S.Faris]

"Solid creation failed, no watertight volume detected". Did you check if any of the 3D objects created is not Watertight. try using the command on a couple of 3d elements at a time and triangulate on to which object is giving you the error.

[leeminardi]

AutoCAD requires the geometry be a solid object for exporting as an stl file.  Are you sure that you have a solid model?  WHat does it say in the properties dialog box for the geometry?  There should be no need to use surfsculpt if the model is already a solid.  It looks like you have a surface, not a solid, for the wall in the area I circled below. Create a copy of your model with only solid objects and then try creating the stl file.  I doubt that facetres is the issue as all the surfaces appear to be flat.  More likely, you are not working with solid objects.  Post the file here and I am sure the forum community will examine it for you.

[Shea_G]

Yea, I believe that is the issue. However, if I create a box using the box command and make no edits to it and that is not watertight, then how can I expect anything I create to be water tight? I feel like there something wrong in my settings if a closed box is not considered watertight.

[Shea_G]

As certain as I can be, the part you highlighted is actually closed because I made the house a shell with a wall thickness. Not sure where the geometry tab is under properties. It shows everything as a "3D Solid" not a surface when I hover over it. Ill attach my .dwg and .stl. I broke the model up into floors with the slice command. Id be extremely grateful if someone could take a look at it for me

[S.Faris]

There are 2 Surface extrusions inside the model. Filter it out and you'll be good to go. I hope.

I moved the Surface extrusions outside of the model just for demo purpose.

[Shea_G]

Yea I saw those before for the doorway. I removed those on the model that I separated floor by floor, didn't change anything. Also deleted every surface in the drawing, no change.

[leeminardi]

There are many non-solid objects in the file.  Do not use a select window for exporting.  Instead, open the properties dialog box and select one object at a time and the properties dialog box should reflect that you only have solid objects selected.  Move these objects to a frozen layer and see  what is left behind.   Give your stl export command when only the solid layer is thawed so you can be sure you do not have non-solids selected.  I was able to create an stl file with just solids selected.

[Shea_G]

I was just selecting the one object with a simple click, not the window. Im quite certain I am only selecting the object as when I check the properties dialog its telling me only "3D Object" not All(4) or whatever number. I also export after freezing everything but the second floor and got the exact same result. Im able to export a STL, It just looks like garbage.

[leeminardi]

I created an stl file in AutoCAD of just one of the solid objects and then imported that solid into 3ds Max.  Here are the results. Not good!  The columns are much different.  The black areas are where the surface normals are reversed. Unifying the surface normals did not help (top image is AutoCAD bottom is 3ds Max).

Importing the dwg file of the one object into 3ds Max yields the following.

Again, not good.  The columns are not square.

What was your workflow to create the columns in AutoCAD?   Did you scale any of the geometry?

[Shea_G]

First off, I really appreciate you putting in the effort to help me on this.

So the columns were made by creating a closed polyline and using the presspull command so that they snapped to the intersecting 3d object, or halfway through it. I never scaled anything in this drawing.

A few things to note:

1. this model exported perfectly fine the way it sat when the USC was rotated. Im not sure if that has anything to do with the problem however, just pointing out I got this model it export perfectly at one point in time.

2. I just created a box, then another box, intersected them, unioned them,  and exported an stl. Literally nothing else. Same issue, wonky geometry. This confirms my belief, it is not an issue with this particular model, as I cannot even get a box to export properly. It must be an issue with my settings or workflow.

3. I opened a new drawing, tried #2 again and it worked fine, two boxes unioned perfectly, copied my model and pasted it into the new drawing and wonky geometry again.

[Shea_G]

So I thought id try to switch my USC back to however it got to that weird orientation, and what do you know, it exported fine.

[leeminardi · Accepted solution]

I found the problem!  Your 3d house is too far from 0,0,0.  One corner of the house has its coordinates as:

X=338829.400 Y=5566481.273 Z= -0.200

Although AutoCAD supports 15 significant figures I am not sure about stl files which may, like 3ds Max, only supports 7 significant figures.

SInce it was difficult to move the solid closer to zero with the move command I made a block of the solid with a base point at the corner of it. I then deleted the one instance and added the block at 0,0,0 and then exploded it to return it back to a solid.  Exporting this to an stl file gave satisfactory results.

[Shea_G]

Yes!!! That was it, I knew it was going to be something strange like that. Now I know not to have my stuff georeferenced. Many thanks, I can continue to model the rest of my house and send it off to the 3d printer. Cheers.