Join closed polysurfaces

Hi everyone,

I am new to 3D modeling and aparently started with a project that is over my head. I need to turn the helmet into one piece so I can proceed to prototyping. I have tried boolean union but it does not work. Any idea what might be the problem or other command I could use?

Thank you in advance!

versão final capacete de soldar.3dm (11.1 MB)

Hello - start by removing (ExtractSrf) all if the internal ‘fins’,


then Join the remaining parts - see how far that gets you.


Hi Pascal,

Thank you for your help. But it did not work. I think I did it correctly. It resulted in open polysurfaces. I need closed polysurfaces.

versão final capacete de soldar_FORUM.3dm (9.8 MB)

Right well, ‘didn’t work’ is a bit extreme - what it means is you’re not done yet.

Some surfaces do not join - meaning, normally that the edges are out of tolerance - visibly so if you look:

So you’ll need to tune these up and then move on to the next problem, if any. MatchSrf should help you here.
There are a lot of problems to deal with here - may surfaces have edges out of tolerance and/or twisted … I’d rethink how you got here, it might be less work to build it cleanly from scratch.

Sorry didn’t mean to sound rude or anything, I am still learning and these “details” are all new to me.
Well, I have been modelling it for a month now more and less… this is a school project and I have to deliver it soon. Unfortunately I kind of need to learn this on my own so I just tried my best. I will try however to rebuilt it. Do you have any advise on how I can achieve this shape with this curvatures without doing the errors I made?

Hello - my guess is you got here by making surfaces and then OffsetSrf, with Solid=Yes. I would first make sure the outer ‘skin’ of surfaces joins up nicely - Join them and then fix any naked edges (ShowEdges >Naked) and then do your offset of the entire polysurface at once. Note you may still run intto problems where the curvature of your surfaces is very high - you’ll just have to see. I would also guess that you may have trouble joining the outer surfaces - you might not, but it looks a little complex so you might. Do your best and then post the result (outer only for now).



here is the outer. everything joins up nicely right?
re-making.3dm (1.6 MB)

I tried the offsetsrf all at once, but it comes up with the same problems I had before. Some that I had fixed others aparently not. and the final result comes up with naked edges. When I did it I fixed the naked edges by deleting the surface with the naked edges and re-doing it using the surface from 2,3 or 4edge curves.

Yep, you’ll need to clean up a bit but not nearly as much - at least here with an offset of .2.


So, to have only closed polysurfaces, hopefully just one, I just have to correct the naked edges (do you think I can fix them like I said in the previous reply and it will work well?) and join everything?

Thank you very very much for your help! I have already learned two new commands with you!

Hello - yes - but it may be a bit painful - depends on the situation. Overall, once you get it sorted out for your class, I’d try figure out a way to make the thing much simpler and cleaner to begin with, then you’ll have a good start in surfacing.


I will try to do my best. For now I don’t need it to be perfect, it is my first 3D model by myself. I just need to be able to prototype it.
But yes, will follow your advice! thanks again!
Have a good night!


Hi, Sorry to bother you again… this is the best I could come up with, however there is still some naked edges that I can’t seem to find. Any suggestion on how to turn this helmet into one closed polysurface?

Thank you!
re-making 30-05-19.3dm (6.7 MB)