export to stl

[Gerrit18]

Today I drew some cilinders, combined and 3D-printed them. It worked very well!
But I also made a box, 35 x 96 x 3 mm and made some holes in it.
In FreeCAD it looked ok. Exported it to NETFABB basic. Also the same drawing with holes.
But in my slicing program (Slic3r) I didn't see holes and when I 3D-print the drawing, I see some printed cilinders in stead of holes. Any idea?
Thanks, Gerrit

[quick61]

Today I drew some cilinders, combined and 3D-printed them. It worked very well!
But I also made a box, 35 x 96 x 3 mm and made some holes in it.
In FreeCAD it looked ok. Exported it to NETFABB basic. Also the same drawing with holes.
But in my slicing program (Slic3r) I didn't see holes and when I 3D-print the drawing, I see some printed cilinders in stead of holes. Any idea?
Thanks, Gerrit

Hello Gerrit, and welcome,

It's more than likely you selected everything in the tree instead of just the last item. This happens with users new to FreeCAD. It would also help if you attached the file in question and provided your FreeCAD info - Help > About FreeCAD > Copy to clipboard and paste it in your post.

Like this -

OS: Ubuntu 13.10
Platform: 64-bit
Version: 0.14.2911 (Git)
Branch: master
Hash: a2cba17d3f2faf44188298eb16211f7b6bc45358
Python version: 2.7.5+
Qt version: 4.8.4
Coin version: 4.0.0a
SoQt version: 1.5.0
OCC version: 6.6.0

Here is a screenshot fo a tree from a simple part. Notice only the last feature is selected and everything else is grayed out (hidden). This can be selected from the tree, or by simply clicking on the part you wish to export. Nothing else should be selected.

Selection.png (20.51 KiB) Viewed 6725 times

Mark

[jmaustpc]

Hi Gerrit
welcome, I see Mark has posted while I have been typing my response , some of what I have said is still probably useful so here goes...

Please start by posting your FreeCAD "help about FreeCAD" data.

Secondly, if you attach a fcstd file showing an example of the problem, to your post, we would be more likely to give you a definite answer.

Did you model your shape first fully in Part and PartDesign workbenches, then select the final result and convert that to STL?

Is there any chance that you used the boolean tool in Mesh workbench? If so then don't. This is what happens under some circumstances if you use a boolean cut in Mesh workbench using meshes for the cut object and the cut tool.

Did you "import" a stl file at any point? Note that you can import a mesh as a mesh and keep it as a mesh (stl) or you could import and convert it to a solid. Generally importing stl files should be avoided where possible...in most circumstance because the format by its very nature looses a lot of information about your object. Round holes actually become regular polygons.

Here is a zipped up stl file as an example Please have a look at this and see if it works for you in your other software.

96_3_35_Box_with_holes.stl.zip

(5.72 KiB) Downloaded 62 times

here is the fcstd file which created it.

96_3_35_Box_with_holes.fcstd

(14.36 KiB) Downloaded 53 times

OS: Ubuntu 12.04.3 LTS
Platform: 64-bit
Version: 0.14.2867 (Git)
Branch: master
Hash: 32134f64f089afb4ead2bf169d393fb7294abbfa
Python version: 2.7.3
Qt version: 4.8.1
Coin version: 3.1.3
SoQt version: 1.5.0
OCC version: 6.5.0


Jim

[Gerrit18]

Dear Mark and Jim

Thanks for your quick responding.
In my request I forgot to tell, what system I'm using:

OS: Windows 8
Platform: 64-bit
Version: ?
Branch: ?
Hash: ?
Python version: 2.7.5+
FreeCAD: 0.13 1828
Slic3r: 1.0.0.RC1
Netfabb basic: 5.0.1
Pronterface

In FreeCAD I drew some boxes, combined them and made some cilinders / holes in them.
After some try-files I exported the drawning to STL
To control the file / drawning I opened it in Netfabb. It seemed correct. All the holes were present.
But when I wanted to slice the STL-file in Slic3r I didn't see the holes back.
So T tried some and stopped before printing it.
Today I loaded the file in my 3D-print program, Pronterface an at my surprice I could see and print the drawing that I wanted to print.

I added my drawing. Maybe, there's a better way to get the same, but for this first time I'm proud to get the result I wanted.

[quick61]

Good to here it worked out for you.

A few suggestions, take or leave them as you like.

First, if your going to be doing a lot of 3D printing of parts from FreeCAD, go into Edit > Preferences > Part Design > Shape view tab and there you will see a field next to "Maximum deviation depending on the model bounding box". Yours is, as of the saving of your model you posted, set to 0.50. If you change that to something smaller, (I have mine set to 0.025) you will get much better results in your circles and curves when the model is exported to .stl. Here is your model and the one I did with the Part Design Workbench exported to KISSlicer. Notice the way the holes look. That is the difference between the 0.5 and 0.025 setting. On small holes, like the ones you have, this won't make much of a difference, but the larger radius you have, the more pronounced that course mesh becomes. I'v found that 0.025 setting to be a good compromise between speed and appearance within FreeCAD... At least on my machine.

yourmodel.png (4.08 KiB) Viewed 6676 times

mymodel1.png (4.72 KiB) Viewed 6676 times

You might want to take a look at the model I attached. It should be the same dimensions as yours but was built with sketches in the Part Design Workbench. Please note, there is NOTHING wrong with your model or the way you made it. It all checks out and and works just fine exported to .stl. No errors. However, once you get a basic understanding of the sketcher in the Part Design Workbench you might find that it is a much faster way to produce a part.

Mark

[andre]

This is a great tip, thanks!

As a side note, I was getting some strange behavior with moving two cylinders together based on the center. I had them both coincident with each other, but as I zoomed in, I noticed one was still slightly off.

They were off in the X-axis. I used "Boundingbox.Center.x" for both cylinder faces (not the cylinder object), found the difference, then moved the second one. What was odd as that FreeCAD said both cylinder faces had identical "Boundbox.Center.x" after they were moved, but visually they were not coincident. I then looked at "CenterOfMass.x", and they were indeed off by a very slight amount. Something like .000124 or thereabouts.

I changed the setting on my system as I am anticipating doing some 3d prints as well.

[quick61]

This is a great tip, thanks!

As a side note, I was getting some strange behavior with moving two cylinders together based on the center. I had them both coincident with each other, but as I zoomed in, I noticed one was still slightly off.

They were off in the X-axis. I used "Boundingbox.Center.x" for both cylinder faces (not the cylinder object), found the difference, then moved the second one. What was odd as that FreeCAD said both cylinder faces had identical "Boundbox.Center.x" after they were moved, but visually they were not coincident. I then looked at "CenterOfMass.x", and they were indeed off by a very slight amount. Something like .000124 or thereabouts.

I changed the setting on my system as I am anticipating doing some 3d prints as well.

Shiny, happy to of been of some help. The one thing you will notice is that your Boolean operations, especially with spheres, will be a bit slower, but the end result is much better. Like I said, I'v found that 0.025 setting to be a happy middle.

All that fiddling around with cylinders and boxes, moving them into position, etc., can get a bit tedious. Even more so with more complex models. That's why I offered the example of the part built with sketches. If you have Graphviz installed, you can go to Tools > Dependency graph... and look at how the model is put together. Compare the model built with sketches to the one built with boxes, and cylinders.

Mark

[Gerrit18]

Thanks for the suggestions. I've set the preferences to 0,025 and I'll try to work with sketcher.
I looked before at it but could not find the right place to change the dimensions quick enough.
Maybe I have to look better, but I keep trying.
At this moment drawing and printing are going better all the time.

[quick61]

Thanks for the suggestions. I've set the preferences to 0,025 and I'll try to work with sketcher.
I looked before at it but could not find the right place to change the dimensions quick enough.
Maybe I have to look better, but I keep trying.
At this moment drawing and printing are going better all the time.

The dimensions are set when you apply the constraints. After the constraints are applied, any dimensional constraint can be changed by just double clicking on it in the 3D view or a single click in the constraint list in the combo view. Couldn't be easier.

If it would help, here is a video of the Part Workbench being used. There are many others, just picked this one at random.

Mark