Path Generation freezes

Here's the place for discussion related to CAM/CNC and the development of the Path module.
coogle
Posts: 6
Joined: Sun Aug 02, 2020 5:34 pm

Path Generation freezes

Postby coogle » Sun Aug 02, 2020 5:51 pm

Hello,

I'm a new FreeCAD user and recently downloaded it to try to find a new FOSS tool for doing my CNC tool paths. At first going through tutorials things looked pretty great, but when I tried to do something "real" I've hit a wall. I can attach my project file if necessary but to give some context it's roughly 250 MB in size..

Basically, I'm trying to surface a piece of stock and then 3D pocket out a spoon (followed by a contour with tabs). For this I have a spoon STL that I imported using the Mesh workspace, then converted to a solid part as so:

- Import into mesh
- Convert to Part
- Convert to solid
- Refine Part to remove extra faces

This process took *a long* time. I then created a Draft Clone of the part to scale it on the Y axis a bit. The scaled version is the one I want to mill.

When I go into the path workspace I'm able to create my facing path using an 8mm end mill without too much trouble. But when I try to create the 3D pocket (4mm, 80% overlap value) it hangs, apparently forever (I left it running overnight on my 2.9GHz Intel with 32GB of RAM). I finally forced FreeCAD to close after 12 hours of unresponsiveness (I'm on macOS 10.15.5)

Is FreeCAD really just this slow, or am I doing something wrong? Is there anything I can do to try to reduce the complexity of this spoon in order to speed things up?

John
Attachments
Screen Shot 2020-08-02 at 1.49.35 PM.png
The project
Screen Shot 2020-08-02 at 1.49.35 PM.png (289.41 KiB) Viewed 191 times
jmaustpc
Posts: 9851
Joined: Tue Jul 26, 2011 6:28 am
Location: Australia

Re: Path Generation freezes

Postby jmaustpc » Sun Aug 02, 2020 6:04 pm

Your first post, welcome to FreeCAD.

I can't answer you question specifically but I can offer some tips.
coogle wrote:
Sun Aug 02, 2020 5:51 pm
I can attach my project file if necessary but to give some context it's roughly 250 MB in size..
Sounds like it was a complex STL mesh. STL is best to avoid if at all possible, its a lossy format and with complex shapes it can end up with a lot of faces when converted to a solid.

Its unlikely that Refine would make much difference since I imagine that the spoon would have few flat surfaces , and Refine is only going to remove extra unwanted edges on flat surfaces.

Another tip, I see in your screen shot that you are using FreeCAD 0.18, if you want to do much with Path WB you really need to use a FreeCAD 0.19 snapshot release since Path WB is currently in development so there are many bug fixes and new features in the newer FreeCAD.

Jim
chrisb
Posts: 25699
Joined: Tue Mar 17, 2015 9:14 am

Re: Path Generation freezes

Postby chrisb » Sun Aug 02, 2020 6:08 pm

FreeCAD is not optimized to work with meshes. They are a degraded file format which may serve for output but it is not well suited for input. How many faces does the mesh have? Werner mentioned here a limit of approximately 100000 without even working with Path workbench.
It would probably be sensible if you remodel the spoon from scratch, although I have to admit that it's daring for a newbie.
etrombly
Posts: 114
Joined: Thu Dec 05, 2019 6:50 pm

Re: Path Generation freezes

Postby etrombly » Mon Aug 03, 2020 3:06 pm

What version of freecad are you using? There was a bug in 3D surface and pocket that was recently fixed. It was causing an infinite loop, so it would never finish.
coogle
Posts: 6
Joined: Sun Aug 02, 2020 5:34 pm

Re: Path Generation freezes

Postby coogle » Mon Aug 03, 2020 7:07 pm

Thanks for the welcome!

Per the advice, I upgraded to 0.19-dev using conda (macOS 10.15) and I was able to make some headway with 3D Surfacing... although I posted a problem I had making that work as well (see https://forum.freecadweb.org/viewtopic.php?p=421374).

Unfortunately when it comes to models I can appreciate why STL sort of sucks, but it's everywhere. In this case, I was able to use some tools to reduce the number of faces of the spoon to something more reasonable and that speed things up considerably.