3D Toolbox: Intersect Faces on Cap/Topper

Im currently working on a cap/topper in Blender. This has been set up for 3D printing and Im using the 3D Toolbox Script to make sure everything is suitable for proper printing. For the most part, I understand the tools presented in the toolbox. What I cant figure out is “intersect face” count and what it means.

Here is a result on this “open mouth” object:

…and the basic measurements, with the non-manifold edges highlighted (composite between object and edit mode)

Want to figure out what might of happened to cause this. Is this expected of open mouth objects? If not, what needs to be fixed and how?

I reproduced that simple mesh and clicking on the Intersection button of the 3D Print toolbox display " Intersect Faces : 0 "

I don’t know what is really going on for your case, maybe try W-> Remove Doubles in case you have doubled faces/vertices without knowing or press ALT+H t unhide everything in case you have a part of the mesh that is currently hidden and may be responsible of that problem.

In case it’s not either of those problems, upload your blend for someone to check.
IF attaching it does not work for you, you can use http://www.pasteall.org/blend/ to upload a blend

Thanks for the information. Due to me working off CAD proportions and curves, I had created a simple curve and then used it to “spin” for full circle, allowing me ot use the proportions I already had. When I saw your response, it occurred to me that you likely re-created the shape for troubleshooting using a simple cylindar. You then extruded it upward and created the taper with scaling.

I tried that very thing to see if I would get better results in mesh analysis. I also got a clean mesh (like you describe) with no alerts and errors doing it that method. Given that sme of my other construction has other curves that are “spun” around the axis, any chance you might know a “gotcha” when using that construction method with 3D printing?

Curious question on the experiment you tried when you made my form from extruding a cylinder…any chance you can try applying a solidify modifier onto it, thickening it. I noticed that my extruded model also was free of intersect faces. Great. However, when I applied the solidify modifier (to give it thickness), I analyzed the model again and suddenly, 33 intersect faces.

Are you sure you have given enough thickness to the solidify modifier ? on my test from extruded circle, still 0 face are intersecting after applying a solidify modifier.

As mentionned before, without you uploading your blend, no idea what’s going wrong if you did the mesh clean up mentionned prevously already.

Yes. In total, the item is 4.3cmx4.3cm and 1cm tall. (a circle). I output 2, one with 2.7mm thickness and another with 4mm thickness. When opened in Makerware, all thickness is recognized and no errors pop up. I even went through with a printout and it prints okay. the part where it tapers smaller (towards the top of the object) is where I do see the extruders going over in a strange fashion. Whether that is a demonstration of the problem with having intersect faces or not, I have not yet determined.

Now that I am mostly done with my experiements in figuring this out, yes, I can provide a blend file. Please see attached.


capdemo.blend (548 KB)

I think i finally found the problem, you changed the scaling unit and apparently it’s preventing correct calculations with other tools, that’s something i didn’t knew

Here’s how to fix the problem on your mesh

  • unhide your object named " 00A Exhaust Cap - Curve Spun At Origin " , then in the 3D View select it

  • in the panel, reset the scaling unit (you have set to 0.001) into 1.000

  • With your object select, and in Object Mode, press N to bring the N-panel and change the dimensions :

into what you needed (type them manually) :

Notice how the scales have been changed to 0.001 0.001 0.001 ?
Now with your object selected , in the 3D View press CTRL+A and select Scale to “apply” the scaling you just did (you will notice it will put back the scales to 1.000)

Then, with your object selected, go to Edit Mode and go into Vertices selection mode

Select all and press W -> Remove Doubles , it will have removed 48 vertices that were on top of each other (and probably one of the responsible of the face intersecting as there was then certainly overlapped faces on your mesh)

Press CTRL+N to recalculate the normals (always something to do after removing doubles, so you avoid bad surprises later)

Click on “Intersection” in the 3D Toolbox and you should have 0

with a scale of 1 your are at the limit of precision for measuring in blender
what you see in n panel might be correct !
max 7 digits

if you work with a scale of 10 I think it might give more precision on the low side

happy bl

Thank you for that detailed summary of what you did. I got the results as expected. When I did a test on intersections, it showed no intersect faces this time.

Now, this is the current results I get if I do “Check All”. This is the result whether the object does or does not have the 3mm solidify modifier on it or not.

See if you get the same thing when you choose “Check All”. Might mean that we replaced one issue with another but damn iff thats not a closer move in the right direction. :slight_smile:

After adding an applying a 3mm solidify i obtain the same results as you with the “check all”

But i don’t think those are real issues, but more to do with the object being very small.

By example in Edit Mode, select all and press S then type 10 (to scale 10 times) , the “Check All” will give Zero Faces being 0 , meaning that previously the 3D toolbox detected the face as being too small and considered them as “0 area” faces, despite they were obviously not.
This i don’t know if it’s a bug of the 3D Toolbox or if real 3D printers have trouble with object only a few centimeters big, that’s probably something to ask on a 3D printer website (or if they have a FAQ look into their acceptable dimensions)

For the thin face, look into the 3D Toolbox panel, it has the minimum thickness set to 70cm ! that’s ridiculously huge.
Lower that a lot, as if i look on one of the 3D printing website, they can accept much lower

If you change the 70cm into 2mm you’ll have no more faces considered “thin faces” (as the solidify modifier was set to 3mm anyways)

For the overhang, i have no real idea what cause this, i thought it may be the sharp angles, but some of the faces pointed to have a rather small angles, way below 45 degree , no idea if it is a real problem with 3d printing though, again better look on whatever 3D printing website faq if they talk about this

Not sure about that. I have been working with alot of objects that might be 4cm at its largest measurement and dont always get errors like this. However, I did notice that my .7mm thickness that I set as the min. thickness (the average min. wall thickness in Shapeways providing that you are not trying to print in metal) got changed to 70cm when I changed the scene’s scale. Didnt notice that when I posted my last thread.

If I scale the object up to 10, all the other errors (thin faces, zero faces) go away. Overhang face goes to 0 before thickening and back to 135 as soon as I add the thickness. Before changing the scale from .1 to 1, I had no issues with scaling when brought into Makerware. Makerware saw it as a 4.3cm sized object. When I changed the scale to 1 and then exported that same 4.3cm to an stl (all scale,rotation,translation reset), Makerware said the object was .4mm big.

Overall, I might just need to tweak the min/max settings for those things since Im not printing that big (cant imagine any reason to print a 45cm object), even if it does fit in the print area of my 3d printer.


In experimenting with the scale size, Im still not quite there yet in getting good results for the slanted area and the top flat spot. I guess it will be a matter of tweaking.

However, of note, here is the article I had originally used which is what suggested the .001 scale.

Im using Makerware. I tried a setting called “Number of Shells”. I popped it up to 6 and that seems to create larger density in the big areas where the printer uses a honeycomb like form. Im also going to re-open both files (one with the 1.000 scale like you advised and the .001 scale linked to in that article) and see what happens when I add sprews/supports