3D_Ron
1
Hi Guys,
I have an application where I have two different STL files that I need to merge into a single STL object for printing. I understand that I need to have internal surfaces eliminated in the areas that overlap. Are there any good STL editing applications (preferably free, but at least affordable) that can do this???
Ron
Xeno
2
I think MeshMixer will do the trick, and is free 
3D_Ron
3
Thank you Xeno. I have MeshMixer and I’ve been playing with it. My challenge is that each of these STL files have been assigned the same coordinate system in the CAD software that created them and it is critical that they overlay in exactly the correct orientation. How do I get MeshMixer to do this?
You can import both models into tinkercad. Move them where you want them.
Then, copy one model, subtract it from the other model. (turn the first model into a hole, and group both models)
You will now have one model that has the second model subtracted, and all should be good.
FYI, most 3d printer slicers can take overlapping models. It ignores the layer that overlaps from one of the models, and prints perfectly.
3D_Ron
5
Thank you Perry! The problem I’m having is with this part of your answer: “Move them where you want them.” In my application, the two original objects are created and exported in the same coordinate system. I need them overlayed in the exact positions described by the original CAD system. I can’t rely on manually positioning the two objects. So far every STL editing application I’ve tried ignores the coordinate system of the two original objects when importing them.
Hey Ron,
the problem you have to deal with is .stl does not contain any attributes of the model that reference to the original CAD model. The coordinate origins and orientations are not stored in the .stl file and therefore not applicable. If you can’t get the source files you won’t be able to position your 2 parts that precise. So I guess the best you can do is use Meshmixer to arrange them by hand and check the file using for example netfabb model repair service https://netfabb.azurewebsites.net/.
(sorry for bad english, I’m not a native speaker)
Greatings!
Ron,
You keep adding gotchas that were not in your original questions, lol!
So lets get things explained in order.
1. You said “I understand that I need to have internal surfaces eliminated in the areas that overlap”
This is not the case. If you overlap, they will print fine. OK thats out of the way.
2. Next, you say you cannot move the items where you want them, which is new information. However, I am still going to stick to my original answer for now, as I believe you think this is true, but it probably is not
Mastercartman explained the issue. STLs don’t have coordinate information. Only triangular descriptions of how the model is shaped. He made the assumption you do not have access to the original CAD files, or that you cannot get them. IS THAT THE CASE?
If so, then you have to proceed with what you have.
Here is what you need to know: The printer extruder prints within certain tolerances, that is, the print has only a certain, imperfect resolution within certain tolerances. On most FDM printers, the tolerances can be with some factor, such as .1mm or something. So that is how close you have to get it.
This being the case, you only need to get it that close. Since my proposed Tinkercad solution allows you to move the model in any xyz plane using arrow keys set at movement of .1mm, you should be able to get it within that tolerance. Unless you don’t actually know how they fit together, in which case you have a real issue.
Is there any way you can post the models here so we can give it a try?
If not, post them to my hub and I will try it.
3D_Ron
8
Sorry I didn’t include the coordinate system issue in the initial question. And yes, I can provide sample files.
When I open these STL files in my STL viewer, they are positioned exactly as they should be against each other. However, when I open them in MeshMixer, they are in a completely different orientation and position relative to each other.
I will try to post the STL fiels to your “HUB” (I am new at this … can you tell?) along with some screen shots from my viewer showing how they should be oriented.
Click here.
https://www.3dhubs.com/cleveland/hubs/perry/3dprint
Click the Big green NEXT button
Type a comment.
Click the Big green NEXT button.
Attach the files.
I will take it from there…
You don’t have to choose me as your 3d printer if I can get this working, you know.
you can try PRINSOW, it’s a freeware, good for merging and spliting STL files, but also for ASCII/BINARY conversion.
https://www.youtube.com/watch?v=O-iDrrr_l_c
