I have two objects that feature similar shapes on various sides.

I want to snap those similar sides to each other in a way that they are matching each other - that is, that they are both oriented so that they face each other, rotated that they align and possibly scale so that they match.

Can anyone give me a hint how to do this? In read a lot about snapping and watched some tutorials and I also tried this add-on: https://wiki.blender.org/index.php/Extensions:2.6/Py/Scripts/3D_interaction/Precise_Align

However, I can't get this to work. There must be a way, I know I have done this before in Autodesk Inventor, but I can't remember how and I can't use Inventor anymore anyways.

In the end, I want to snap several of them together and use array modifiers to tile them in space.

Here is an image of the objects I want to stick together: enter image description here

And here the file: http://www.pasteall.org/blend/41722


  • 1
    $\begingroup$ Related: blender.stackexchange.com/questions/39784/… $\endgroup$
    – Paul Gonet
    Commented May 6, 2016 at 12:15
  • $\begingroup$ Blender is currently very lacking and unsuited for precision modeling and CAD like transformations, there is no built in easy way to do it. The addon you mentioned seems to be the closest you can get. You could also try this addon, although I think it is not exactly what you are looking for blenderartists.org/forum/… $\endgroup$ Commented May 6, 2016 at 12:36
  • 2
    $\begingroup$ Possible duplicate of How can put a mesh into a different position? $\endgroup$
    – Carlo
    Commented May 6, 2016 at 18:04
  • $\begingroup$ Precise align did a good job in my test (i.sstatic.net/ks2bO.gif), could you specify what exactly you didnpt manage to get? $\endgroup$
    – Carlo
    Commented May 6, 2016 at 18:16
  • $\begingroup$ @Carlo that's exactly what happened to me, too - I can't get them to be facing each other. I can align them, but they are both pointing in the same direction. When I change the z vector the other coordinates change too, because only right-handed systems are allowed. $\endgroup$ Commented May 7, 2016 at 1:04

1 Answer 1


Flip Normal Vector

For the sake of clarity, after recaluculating normals, I colored the faces to match in blue and the triangle that we'll be use as pivot in red.

enter image description here

Letìs get into edit mode, pick the tris and run the Create Empty operator. Note that we can change the vertex of application with the Swap Empty Origin button.

By examining the empty arrows, we can say that our Z axis is normal to the tris surface and pointing toward the inside of the object, the X is running along the smallest edge and the Y is going where it must be.

enter image description here

Chamge object and repeat the process being sure to choose the right vertex. You can switch the normal vector of the empty by checking the box in the command's options or even remap the whole axis system if needed.

In this particular case we'll need te X axis to be running along the short edge and the Z axis to be pointing outside the object, in order to make the faces ...ehm..."facing" each other.

enter image description here

Finish by matching th empties location&rotation and then eventually adjust the relative scale.

enter image description here

  • $\begingroup$ Ok, I'm still stuck. I can't get the vector of the empty to align with any of the other sides. The z vector is pointing in the correct direction (inside or outside), but the x and y axis are pointing in directions not aligned to any of the sides. So your write-up is really helpful - yet I'm still stuck at this part: "In this particular case we'll need the X axis to be running along the short edge". My z axis points correctly inwards along the edge going "inside" but neither the x nor the y axis are aligned to any of the other sides, I can't "rotate" them around the z axis to align to a side. $\endgroup$ Commented May 9, 2016 at 8:57
  • $\begingroup$ And thanks for your great help so far! This is exactly what I want to achieve (in your last gif), I just don't know what I am missing. $\endgroup$ Commented May 9, 2016 at 8:57
  • $\begingroup$ It never happened to me that none of the other axis wasn't running along one of the edges. It's even explicitally named "Edge" the axis in the mapping opton. That's strange, could you post a picture of the tris and the empty or upload a file with your empty in the wrong position? $\endgroup$
    – Carlo
    Commented May 9, 2016 at 21:32

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