Join multiple stl files that come from a split model

[giannis.psychogios]

Hello everyone,

I have some stl files that when printed, they combine into a statue (each piece locks into another, there are aligning pins). I would like to print them as the original model was, pre-split. Is there any easy way to do that and reverse the split, or I have to manually align them?

Thanks in advance.

[hfcandrew]

Yep read here: https://forums.autodesk.com/t5/meshmixer/properly-merging-multiple-stl-for-3d-printing/td-p/10097022

[Anonymous · Accepted solution]

If your model comes with different surfaces combined to one file like this:

I recommend to EDIT/GenerateFaceGroups as a first step to ease later selection. The goal is to get a single group for each "contact surface":

Now run EDIT/SeparateShells to get a separate object for each part.

Next step is to roughly align one source object to a target object.

With the source object active run EDIT/Align. Set Source to SurfacePoint and Target to SurfacePoint.

Click on some point at the source object (the transparent ghost)and Shift+click at a corresponding point at the target object.

This roughly alignes the source object to the target. You may drag the green triangle in the widget to move or the green arc to rotate the source object at its target position.

For fine registration you need to set the target object as a Target (enabling the magnet icon in the ObjectBrowser).

Now, with the source object being active, go to SELECT and double click its contact area group (the green group in the topmost image) to select it.

Run Edit/AlignToTarget on this selection. Hit ImproveSolution several times until the source object doesn't move any more:

Disable the magnet icon in ObjectBrowser.

Now you might want to join both surfaces to a single one.

To do this hide one of the objects. With the other one active go to SELECT and double click the contact area group to select it. Add the registration hole to the selection using the selection brush:

Hit X to discard this area. Do this on the other part too.

Now activate both objects (Shift+click to activate a second object) and do EDIT/Combine to get a single object.

Go to SELECT, set a small brush size and zoom towards the open boundaries.

Double click on the boundaries on both sides to select the boundary faces:

Run Edit/Join on this selection to weld the pieces to one.

Accept and done...

[hfcandrew]

Haha, your reply was infinitely less lazy than mine! 

[giannis.psychogios]

Thank you so much for the detailed and informative response!