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3D Printing problem Help!

ZBrush Usage Questions
#1

Hello all, I am new to Z-Brush and am thus far delighted at its capabilities.
I am trying to print some character models on a Dimension printer from Stratasys.
I have tried everything to prevent unwanted internal surfaces in the .STL files.
Merging Sub Tools, and Decimation Master all seem to work well but the stl file still contains the origina sub tool boundries within my models. If for instance I mask a figure and extract to produce a clothing sub tool then I can see three distinct surfaces within the STL file: The Character’s skin, The outer visible part of the clothing and an inner (hidden) surface of the clothing.
These boundries play havoc with tool paths and reult in support material being trapped within the printed model spoiling the surface. I need to be able to export only the merged visible outer skin of he model.
Is there some way to trim out this internal geometry??

Many thanks

John

#2

Do you have some pictures or files as an example of what you’re talking about?

Also it doesn’t always matter if you have support material trapped inside and usually this is done on purpose to save on material costs, e.g., making a big model hollow. However as far as I’m aware you to actually create a hollow model with a pinhole at the bottom or else the printer will just close it off even with faces inside. This may or may not be the case with your printer and the software it uses.

I use both 3DS and Objet printers and that’s been the case. However I have not done multiple tools. If I needed to I would merge the tools into one.

#3

My experience with printing has also involved hollowing out the model (zcorp/3ds, this wasn’t needed with plastic-based printers), and using multiple tools/polygon islands pushed into each other.

As for doing only the outer surface, remesh and dynamesh should both let you achieve a single, solid mesh. Just use the highest resolution you can to capture the detail you need, then run Decimation Master afterwards to cut the filesize back down.

#4

Even merging subtools and dynameshing will leave artifacts that don’t show up in zbrush. I have been using dynamesh to boolean all of my subtools into one closed volume for a few months now, and it is awesome, and frees one from having to merge numerous shells in an app like Magics. There will still be ghost/noise shells and inverted normals and other minor issues which still must be cleaned up. I have been using the free version of Nettfabb lately, and it works fairly well. It is still not as easy as Magics, but Magics is 8 grand! Give Nettfabb a spin. Also, make sure all of your meshes are inner penetrating before you do the dynamesh join. Some service bureaus will say that multiple shells are ok, but I say better safe than sorry. I try to merge as much as possible, and for me, that is one shell. If it needs to be multiple parts, and was not modeled that way, with tabs and slots and all that, I merge it all, then cut it up and add registration pins (though usually in another program…definitely a Magics job. It has the best boolean functions I have seen.)

Some one needs to come up with the “STL CLEANER” pluggin. Then it can all be done natively in Zbrush:D Surely one of our brainy members can tackle that!

#5

Almost all printers can handle inner penetration of geometry. Most just read it as independent volumes until printing actually starts and then it figures out that you can’t fill the same space 2x…damn physics :). Anyway, 3d printing software is reading volumes of all manifold objects.

If you really want to remove extra stuff from a .stl the easiest way I have found is to actually export out your highres mesh to 3dcoat…or any other voxel based program. These work with volumes so it’s very easy to shell an object with a set depth (2mm or so) as well as remove any unwanted small errors that appear in a mesh as you can hide objects by volume which will reveal all of those little errors inside of your mesh.

It’s also very nice because it is working with volumes which is basically the same output you’re going to get when you print anyway. I don’t find 3dcoats tools to be as robust as Zbrush in some instances, but it stops zbrush in regards to retopo and 3d painting. Hopefully the new Qmesher will remove at least one function of my pipeline out of 3Dcoat. Now they just need to work on letting me paint on my damn UVs.