Pulling my hair out trying to split a model

[lucchij1]

Hello. I've been trying to 3D print a model of the Hawkmoon Moonglow from Destiny 1 (picture attached). I have a Bambu X1C. I found a great model online broken up into parts, and even got everything printed nicely, except the barrel. I am trying my hardest to do it entirely printed, no paint. Multicolor prints of the barrel takes an insane amount of time and (wasted) filament and are not an option with my current printer. I've managed to get the feathers isolated to facegroups(file attached), but am struggling with where to go. I did managed to extract, thicken, and then realign the feathers to get a preview of the multicolor print (feathers attached). My next thought was print a barrel with inset holes where I could then insert separately printed feathers, but any of my attempts to cut in holes for the feathers have failed, either through various means in meshmixer or using those thickened feathers to subtract from the barrel I would really appreciate any advice or help that can be given.

[hfcandrew]

Edit > Generate Complex > Edit > Split Complex

https://help.autodesk.com/view/MSHMXR/2019/ENU/?guid=GUID-9B841401-44A5-4CDE-915C-BCE1FB3561BB

https://help.autodesk.com/view/MSHMXR/2019/ENU/?guid=GUID-DD510C7D-9F39-4141-81CD-E0EE625C3BFD

https://www.youtube.com/watch?v=PCgP8VLFaz4

[lucchij1]

Hello. Thank you for the input. I thought generate complex would be the way to go, but I had two main struggles.

1. I was only able to get 3 of the 6 feathers to give me valid facegroup boundaries (and of course not on the same side). I actually had 1 before, but I managed to fix 2 of them by deleting the facegroup and separating shells to find small hidden triangles. However, even with no shells being generated at this point, the other feathers still do not show as black borders.

2. When I select the valid feathers during generate complex and then split complex, the inner surface of the barrel and backside of the feather have terrible geometries. I guess the tool doesn't know I want a flat interface. Is there anyway to clean this up or prevent this?

[hfcandrew]

Sorry I didn't look at your attached models.

You did not attach the barrel model, and also your feather models are non-manifold and will cause the MM tools to behave unexpectedly. The feathers have 6 objects that contain over lapping walls, zero thickness walls, intersecting  triangles. This an object that cannot exist is real life. It was not a model designed with 3D printing in mind. It will take a lot of clean work to make it work.

To use complex you need to first use stamp to apply a custom facegroup of your feathers and apply it to the barrel. The generate complex and split.

Otherwise you could also make the models manifold and solid, then boolean subtract them from the barrel.

Also I think your attempt to thicken the feathers is what maybe made the feathers non-manifold. If you attach the original model I could take a look. I fixed one for you for an example. took like 30 mins though, so I'm tapping out from here, but see attached.

[lucchij1]

My bad, I attached the grip I was working on instead of the barrel...I've attached the barrel with my Facegroups made and the most basic form of the barrel I have. The barrel already has the feather detailing it in, and I had to do some selection work to isolate them as facegroups.

Yeah, I thought the feathers had errors, though inspect never popped anything up but it was not my main focus of troubleshooting. I agree, the feathers I extracted are not ideal, but I thought it could be helpful.

I thought about stamp but I'm not sure it makes sense since the feather detail is already baked into the barrel model?

I tried boolean subtraction but it took about 5 minutes to process and just gave garbage. Not a surprise with what I gave it.

I definitely agree I messed them up. From the facegroups, I extracted then extruded but the extrusion gave me artifacts, obviously. That cleaned up feather looks a lot better, but I think it will be even easier starting from the original model and doing it properly.

[hfcandrew · Accepted solution]

Yep that certainly does make it easier.

Okay so complex will fail on this model for many reasons, but you can 'generate you own 'complex' manually.

See a previous post here with the same issue: https://forums.autodesk.com/t5/meshmixer/when-i-generate-a-complex-it-fills-in-a-section-i-want-empt...

[lucchij1]

Ok, ok, I think that figured it out!

I first had to remove the inside edge of the feathers from the facegroup. I knew that would mess up later steps. This is a problem for the other 2(4) feathers, but I think I can modify the geometry to fix it. Then I pretty much followed exactly as you did in the video, with one important difference.

1. Select feather facegroup.

2. Separate.

3. EXTRUDE to flat with enough negative offset to not get fold over triangles (or whatever the proper term is...) but also not intersect barrel hole.

4. Duplicate result, select original section, and delete.

5. Flip normals of resulting shell.

6. Combine with barrel and weld boundaries.

I have yet to print this, but I did slice it and it sliced fine. I'm not sure what the artifacts in the bottom of the hole are (picture 2)...I did try it with inspector/erase&fill, but the geometries never worked out nicely and gave much worse results (picture 1). I also sliced the feather from the extrusion method and it came out fine.

It's going to take me sometime to fix the geometries and do the same to the other feathers, plus print a barrel and 6 feathers. But for now I believe my problems are solved?

[hfcandrew]

Those artifacts might be the back faces of other triangles, some sort of a noisy double wall. But if it slices, then it doesn't matter.

[lucchij1]

Andrew you are a lifesaver and a wizard at Meshmixer. I ended up not having to do much to the other 4 feathers, printed them all and a barrel, and they came out great!

[hfcandrew]

Oh very nice! Glad to help.

Did you have to end up adding like a 0.3mm offset or anything for some wiggle room so it could fit into place?

[lucchij1]

Thankfully not! I've printed similar fits with this printer before and 0 tolerance has worked. It was a tight fit, but I used a soft, small hammer to tap them in.