Saving STL's with Negative Volume WITHOUT the Negative Volume ?  

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

That is what it is. It does not save stl with negative parts. The best you can save is the project as an 3mf file. 
to get an stl like you want you have to use other software, like a CAD program, blender. 

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

I think it depends on model geometry. I have examples of models modified with negative volumes that saved fine. Why it is that some do, others don't, no idea.

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

A STL file is just a pile of triangles. It doesn't support any distinction between positive and negative volumes, or any actual notion of volumes. Generating a new mesh with the negative volumes removed requires doing boolean operations on meshes, which is very complex and something that I'm entirely unsurprised that they don't want to mess with. The same operation can be done much more easily in 2D during slicing, but the output is of course not a mesh.

If you need a modified STL, you are better off using an actual mesh editing program to do the job, not a slicer.

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

Thank You for your response.  I honestly don't even know what I'm asking is even possible because I really don't even know HOW to ask what I want to ask...   Hahahahaha

As an example imagine a square , I want to create a negative space ON the square removing some of the square itself , and then save the file as what's left of the " edited " square...

SADan

Posted by: @sadan

I've been trying to work out an issue and didn't know it it's something that could be done in the first place so I didn't report it as a bug.

I've used a file and have edited it using the Negative Volume to take out things I didn't want in it.

When trying to save / Export the STL  Export Plate as STL/OBJ I get the Error below :

ERROR:Unable to preform boolean operation on model meshes. Only positive parts will be exported.

It does save the STL , however ALL of the Negative Volume areas are removed and it's like I never added any in the first place.

Am I doing something wrong or is there a way to save a file as an STL with all the Negative Volume areas removed.

Thank You for You Time ,

 

Respectfully ,

 

Dan

 

 

 bcbebe7b-error-unable-to-preform-boolean-3-both-images-.jpg

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

Thank You for your response.   And I too have 100% No Idea on how this works.

The file I'm working with , I've already printed it a few times.  I'm bracketing it to get the size correct.  And when I print it , I load the STL , it shows the STL ( of course ) but it also still has all the negative volume areas in it.  I'd like to have a way to save the STL with the the negative volume areas removed from the STL itself.

Still working on it by trying other programs but that is where I also get the boolean issue...

SADan

Posted by: @fuchsr

I think it depends on model geometry. I have examples of models modified with negative volumes that saved fine. Why it is that some do, others don't, no idea.

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

I tried to add the STL but wasn't able to.

SADan

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

STL's Must be ZIP COMPRESSED before you can add them to the forum pages

regards Joan

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

Thank You...  

DONE !

SADan

NegativeVolume

Posted by: @joantabb

STL's Must be ZIP COMPRESSED before you can add them to the forum pages

regards Joan

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

As far as I know, the only way to (kind of) work with negative parts of objects, is when the cut tool is used. These can be exported. I did not see any working examples (as said by fuchsr) yet. Would be interesting to study such examples to understand what makes them work. 

So what I did (to help you a bit further): 
- In prusaslicer: 
1. Turned all the negative objects into positive objects. 
2. Split the part into objects
3. Merged all the "Generic_***" objects into an stl
4. Same for all the non "Generic" objects (your original stl) into an stl
Exported both as stl (what is easy because both are positive parts now)

Imported them into Blender (but also possible in Freecad and many other apps)
- boolean operation
- where the "negative" stl is subtracted from the "original" stl. 
- apply
- delete "negative" stl
- export "result" stl. 

All included in attached zipfile. 
PS: Looking at it, you are probably not satisfied "yet". 
Suggestion is to learn a 3d drawing program (like freecad, thinkercad and many others). 
Import the original stl; turn it into a solid; and use this as starter for your own drawing. 
(that is not faster, but more easy to modify if needed, and you learn how to do this for other projects" 🙂 

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

Sometimes a THANK YOU just simply isn't enough...

For me , THIS is one of those times...

Please let me buy you a cup of coffee or something along those lines.  Charity donation in Your Name , anything I can do , REALLY !

I'm a bit older so if I say you just taught me how to fish , it means more to me than you think.  Like you said , I can use what you taught me on other projects !!!

I did also notice that had I printed this one as I WAS gonna do , it would not have had a strong enough area at the cut out circled areas to maintain the strength it needed...   BUT , with what I THINK ( grin ) I know now , I can do this myself...

Honestly ,

THANK YOU for your TIME and patience with me.

Respectfully ,

SADan

- Please pm me to let me know how to send anything.  

Please.

Posted by: @eef

As far as I know, the only way to (kind of) work with negative parts of objects, is when the cut tool is used. These can be exported. I did not see any working examples (as said by fuchsr) yet. Would be interesting to study such examples to understand what makes them work. 

So what I did (to help you a bit further): 
- In prusaslicer: 
1. Turned all the negative objects into positive objects. 
2. Split the part into objects
3. Merged all the "Generic_***" objects into an stl
4. Same for all the non "Generic" objects (your original stl) into an stl
Exported both as stl (what is easy because both are positive parts now)

Imported them into Blender (but also possible in Freecad and many other apps)
- boolean operation
- where the "negative" stl is subtracted from the "original" stl. 
- apply
- delete "negative" stl
- export "result" stl. 

All included in attached zipfile. 
PS: Looking at it, you are probably not satisfied "yet". 
Suggestion is to learn a 3d drawing program (like freecad, thinkercad and many others). 
Import the original stl; turn it into a solid; and use this as starter for your own drawing. 
(that is not faster, but more easy to modify if needed, and you learn how to do this for other projects" 🙂 

 

 1a76fa00-result.zip

RE:

Imported them into Blender (but also possible in Freecad and many other apps)
- boolean operation

BTW: There is also a way to do this in PrusaSlicer: 
- Turn all negatives into positives (see above)
- Create a "negative" stl by merging these objects. 
- Export that stl
And then the new step:
- In Prusaslicer go to add object, scroll down, choose gallery, import the stl into the gallery. 
Now you can use the stl as negative part
Maybe you have to move it a bit around to get it on the right position. 

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

Posted by: @eef

I did not see any working examples (as said by fuchsr) yet.

Trivial example: Add a box to the plate. Add a cylinder as a negative volume. Reposition it so it cuts a piece of the box. This you can export as an STL and reload it. It works for trivial stuff like this but not for more complex geometries.

RE: Saving STL's with Negative Volume WITHOUT the Negative Volume ?

Posted by: @fuchsr

Trivial example: Add a box to the plate. Add a cylinder as a negative volume. Reposition it so it cuts a piece of the box. This you can export as an STL and reload it. It works for trivial stuff like this but not for more complex geometries.

Tried it. And yes it is possible. But also right on: trivial stuff. I could not do anything functional this way. So for daily practice not usefull at all.