Joining two meshes smooths them?

Hi there - I’m working on an keychain for 3d printing, which I have made through a different software, and now I’m just trying to add the bail ring in the top so that it can have a place for the little loop to put your keys on. I imported my keychain design, added a simple torus mesh, and positioned it at the top of the keychain through the top of the mesh. However, when I use ctrl-J to join the two into one object so that I can export it for 3d printing, this action smooths out my keychain object - it has sharp details on it, which you need for clear/clean 3d printing, and it loses a bunch of detail when I do this; can’t really have that. Is there some setting I can adjust, or some other way I can join these two objects together so that it doesn’t affect the geometry of my keychain object?

Thanks!

Modifiers on anything prior to the join? That’s where I’d look. Could just be something like joining A to B, where B has a subdiv modifier. Once A is part of B (same object), then B’s modifier stack is now applied.

When joining two meshes, whatever traits the active object has will end up in the joined mesh. I’m guessing here, but very likely you smoothed the torus so it would look right and the second mesh, when joined, took on that smoothness.

If you bevel the edges that you want ‘sharp’ (very small bevels) you should end up with the final product you’re hoping for.

You cant mix smooth objects with flat ones. If you do that, the one who has a subd modifier will transmit that to the other one. Instead, you need to group em, not to join em.



I’ve done this before and I did have it 3D printed. I boolean unioned the torus to the skull model and then used Dyntopo sculpting to smooth the area where the two meshes come together. It gives for a much better result for 3D printing.

And why the hell do you need dyntopo if you can do the exactly the same thing within blender?? lol… some of you guys are amazing.

Ummm, mine was all done in Blender. I used Dyntopo to smooth the conjoined meshes to make it stronger and remove the intersecting faces created from the union while retaining my detail. I use Blender exclusively for 3D printing. I did not understand the OP’s original problem but I thought I might offer a real world solution to his/her problem.