Trouble With Splitting Surface

zach_morris

I'm trying to build a helmet and extrude only portion of a surface. I have one version of the helmet where it's working, but I'm trying to do it on a second version and I can't understand why it is not working on the new version of the helmet. I received some help on the working version, and I've been going through step-by-step to learn each step of the process, but I'm stumped on "Thicken Main > Thicken 2" I believe it is because I did not split the part properly in "Details - Split 2".

Working Version: https://cad.onshape.com/documents/41920c30e9f890601cf20077/v/14b1858737143a04153a8794/e/a2ea85f24e0895fbd801b36c?renderMode=0&uiState=656cc169bab90e5ee83ba382

Broken Version: https://cad.onshape.com/documents/41920c30e9f890601cf20077/w/bc36e17f21b596ca3cddd4a3/e/a2ea85f24e0895fbd801b36c?renderMode=0&uiState=656cc0eabab90e5ee83ba24c

afalzate13

One tip could be to make split a part with a surface making sure you don't have any intersecting surfaces to avoid a non-manifold condition. You can extrude a surface: 
and then split the part using this surface, if it goes red, there move the vertex corners a little in the sketch or move the surface to avoid the non manifold condition. Then thicken the split shape and reboolean. 

zach_morris

@afalzate13
This does work, but it messes up the aesthetic of the helmet.

afalzate13

This is the solution to the issue, you seem talented enough to solve it once you see what the issue was. Just avoid the nonmanifold issue. I'm sure you can tweak the sketch or create the split surface any number of way to accomplish the aesthetic you want. 

afalzate13

@zach_morris

https://cad.onshape.com/documents/c309a7442a891bceede06252/w/003737301dfaec087bbc0241/e/15b1b5e15828cfb786c4b2ad?renderMode=0&uiState=6576160136fe8f106f09b31f