Issue converting Meshes to Solids

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rwhproductions
Posts: 1
Joined: Mon Aug 08, 2016 9:49 pm

Issue converting Meshes to Solids

Postby rwhproductions » Mon Aug 08, 2016 10:02 pm

Hello, this is my first time visiting the FreeCAD forum, and as such I feel it is proper to express my gratitude for FreeCAD and those who have created/support it. I have a problem with converting Meshes from .stl files I have downloaded into solids so that I can edit them before 3D printing them. I have been using FreeCAD for two years or so, but I've only dealt with the creation of primitives and Boolean operations and have rarely found cause to leave the relative safety of the Parts tab.
What I'm trying to do is create parts for multi-component optical lenses I have designed; the total lens has about 10 elements and each element requires its own unique thread. I have tried to convert meshes with metric threads into solids so I can scale them and combine them with other parts, but every time I attempt to do so, the program ends up freezing and/or crashing, first showing the usual processing icon (the four-quadrant black and white circle), then the Mac processing icon (the multi color swirly circle) and then there is no response (I have left it on for up to 5 hours to see if anything happened, but alas, no response).
I'm not sure if this is due to the amount of faces/ points on the mesh (around 29,000) or if there is something wrong with my computer/software, as I recently updated my Mac to OS X El Capitan. I have followed all of the directions in the FreeCAD documentation (analyzing and repairing the mesh before conversion via parts), but to no avail. I have also uninstalled and reinstalled FreeCAD multiple times, however this has had no effect either. I also tried to convert meshes to solids on an older version of FreeCAD (0.13), but there was no difference in reaction compared to the newer version.
I have resigned myself to try to make threads out of primitives, which seems a rather daunting task, but my inability to convert meshes downloaded from the Internet into editable solids is a severe detriment to my future prospective projects. I've spent a long time searching the Internet for a problem/solution similar to mine, but I've come up dry.
Also, to be honest, I have no programming knowledge, and have no clue about the framework and Python that runs FreeCAD, apart from entering commands I find online into terminal to try to fix my problems (which usually doesn't work). My apologies for sounding like an insufferable fool, but unfortunately my knowledge in this regard is limited to basic functions. 
Thank you very much for reading my post, I would be eternally grateful for any help or advice.

Here is information about my Mac and the version of FreeCAD I have, Thanks again!;
OS: Mac OS X
Word size of OS: 64-bit
Word size of FreeCAD: 64-bit
Version: 0.16.6705 (Git)
Build type: Release
Branch: (detached from acfe417)
Hash: acfe41706cc916a92ca0c366021e4339fb699057
Python version: 2.7.11
Qt version: 4.8.7
Coin version: 3.1.3
OCC version: 6.8.0.oce-0.17

OS X El Capitan
Version 10.11.4 (15E65)
MacBook Pro (15-inch, Late 2011)
Processor 2.4 GHz Intel Core i7
Memory 8 GB 1333 MHz DDR3
Graphics Intel HD Graphics 3000 512 MB
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quick61
Posts: 3673
Joined: Sat Aug 24, 2013 2:49 am
Location: u.S.A.

Re: Issue converting Meshes to Solids

Postby quick61 » Mon Aug 08, 2016 11:35 pm

Hi rwhproductions, Welcome to FreeCAD and the forum.

First off, any optical component that is represented as a mesh is for all real world application, basically invalid. A mesh can never be as accurate as a B-REP solid. Just the nature of the beast, a mesh had no round surface, just a series of tessellated flat faces.

Second off, FreeCAD is not a mesh modeler. Yes, there are some mesh tools in FreeCAD to complement the solid molder, but most of the mesh tools are designed for dealing with a meshed output from FreeCAD. If you really need to do extensive modifications to a mesh model, a program like Blender would be far more appropriate than trying to get FreeCAD to handle things that are not it's primary focus.

Maybe someday we will get a Mesh Design Workbench that rivals Blender in mesh editing quality, but that, if ever, is a LOOooooOONG way off.
points on the mesh (around 29,000)
Trying to convert that many mesh points to a solid is very, very taxing on FreeCAD, and you may very well never see an outcome of a solid if conflicts/errors exist within the mesh that confuses the math used to convert. Trying to convert that complex of a mesh to a solid is like trying to polish a turd, never works as well as you might hope. ;)

Mark
This post made with 0.0% Micro$oft products - GOT LINUX?
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bejant
Posts: 5126
Joined: Thu Jul 11, 2013 3:06 pm

Re: Issue converting Meshes to Solids

Postby bejant » Tue Aug 09, 2016 10:00 am

rwhproductions wrote:Hello, this is my first time visiting the FreeCAD forum
Hi, and I'll echo Mark by welcoming you here.
rwhproductions wrote:I have tried to convert meshes with metric threads into solids so I can scale them and combine them with other parts, but every time I attempt to do so, the program ends up freezing and/or crashing, first showing the usual processing icon (the four-quadrant black and white circle), then the Mac processing icon (the multi color swirly circle) and then there is no response (I have left it on for up to 5 hours to see if anything happened, but alas, no response).
5 hours might not be long enough - you might want to let it process overnight to see if it completes. But even if you aree successful in converting your .stl meshes into solids, I suspect that each modification of a solid with so many faces will take so long to process that you won't want to work with them. My suggestion is that you learn how to model threads because it isn't very difficult, once you know how to do it (and no programming is needed). You'll have to venture into the Part Design / Sketcher WorkBenches to create a Sketch of your thread profile, then go back to the Part WB to create a helix and then Sweep the Sketch along it. Be sure to tick the "Frenet" and "Make Solid" tickboxes to True, or change the properties later if you forget. I have better success cutting a thread from a solid instead of adding a thread onto a solid, so try that way first.

A collection of tips is here:
http://www.freecadweb.org/wiki/index.ph ... w_Tutorial

If you're using standard metric threads pay special attention to the ScrewMaker macro and to BOLTS. You might be able to use them to create threaded solids that you can add / subtract / union to or from your model, or as a starting point.

I know my reply isn't quite what you asked so post back if you need more help or info. If you can post the metric thread type you're trying to model, we can help you get started, and a link to a .stl file would help us know about the mesh you're dealing with.