Cutting Objects in Cura

[jollyro 0]

Gi Guys, it seems to me that for what I do Cura is the best slicer for my printer. I use a Anicubic Mega S. But what I look for is a Add-On or feature in Cura that could cut the object into pieces.  I saw that in some other Slicer Software, but it did not slice well for my printer and I forgot which one that is. 

This would make some Prints so much easier without the hassle to bring it into some other 3D Software, rearrange it and bring it back.

Imaging, you have a Figurine, cut it in Half or cut off the raised arm, lay it down on the bed and print it without these nasty supports all and everywhere. Lot of Material saved. 

If some smart one could do this, that would be awesome.  I have no idea, if this is a impossible task or not. I am a little over 60, I started with a VC 20, programmed a shitload of things in my younger years, but nothing with 3D and now I am to old for that anyways nor do I have the tools for it.  I used to be a chef, chefs do normally not need any programming skills....

[ahoeben 1,948]

Cutting objects at an arbitrary cutting plane is surprisingly more complex than you might think. It is not just a matter of removing all points on one side of the plane; it is very likely that the plane cuts halfway through a lot of faces. New vertices need to be added and connected into new faces, and the model needs to be kept "watertight" by adding caps to all now open areas and then still manual repairs might be necessary. It is a task that really needs to be done in an application with a much firmer grasp on the geometry than the Cura frontend has.

[spauliszyn 0]

Maybe 'cutting' the model is the wrong concept.  It may be easier to subtract or crop.  Cura already has an option to subtract supports using an overlapping object.  It can also even change print settings for a volume defined by an overlapping object.  Why not have a "do not print" or "only print within" options?  Then you could import a 1cm cube, stretch it as required and use it to define a volume to print or volume to crop?

 

You have to realize that most 3D files available are stl files which are not as easy to modify as solid geometry models.  But most of the time I only want to take an stl from Thingiverse (or elsewhere) and crop parts that I don't need or split them up if they are too big.  This option would seem like a very basic yet versatile tool. 

 

And you can't say that it is too complex--not for the brainiacs at Ultimaker that are already making this kind of software.  😉

 

 

[GregValiant 1,251]

"I used to be a chef, chefs do normally not need any programming skills....".

I beg to differ.  You had to flip over the little glass thingy with the sand in it to program it for 3 minutes.  I would consider that analog programming.  The oven controller had to be programmed for temperature and start time/end time.  That's digital programming.  I think you're selling yourself short.

 

The support blockers can be used as mesh modifiers.  Drag one over, resize it, set it to "Cutting Mesh" and enter the appropriate settings to keep anything in the overlap from printing.  Typically setting the Wall Thickness, Top Layers, Bottom Layers, and Infill Density to zero for the overlap will do the trick.

[dougeldridge01 0]

@GregValiant but how do you then remove the blocker post slicing so that you can have a viable model to add supports to in the gap you have created? If I leave it there it will prevent supports. I have watched 3 guides and no one ever comments on this. I want to create a cube gap in my model to insert a cube weight. 

[GregValiant 1,251]

I typed this earlier and then walked away without submitting it.  Sorry.

 

If I understand correctly -

Typically your insert becomes the support.  Whether its a nut (a problem because of the hole) or a magnet, you know it's thickness so make your "Mesh Modifier" block that thickness.  Set a Pause at Height at the proper layer, insert the weight and then allow the print to resume.  It will simply print over the weight and put a roof on the cavity.  It will be messy for a couple of layers.  You could put a piece of painters tape on the weight to make it more "bed like" so the extrusion would stick.  If you do that you have to account for the added height so the nozzle doesn't whack it.

[dougeldridge01 0]

@GregValiant Thank you so much for taking some time to respond, no problem.

 

So ideally I would not like to stop the print and add the weight for various reasons. I would like to take the model as you see it here post cut and rotate it 180 degrees so that the cut square opening is on the bottom of the model. Once in that orientation I would like to print it, the reason being there are chains on the other side that could get scarred by supports. 

 

But if I rotate it 180, it will need supports in the cut out square area. Because the blocker is there it wont print supports on the interior of that square opening. I just don't understand how to remove the blocker post cut so I can get supports in there. 

[GregValiant 1,251]

This is starting to sound like one of those things where the model you are giving Cura to slice isn't really the  model you want.

If you are on Windows you can download "MS 3D Builder" from the Microsoft App Store.  It's not an intuitive program but if you open your model in it you can bring in a cube, size it and move it where you want, and then subtract the cube from the model.  You get a model with a cavity and it should get supports.

 

[dougeldridge01 0]

@GregValiant Well I guess it would be more succinct to say that I am trying to use Cura to cut a shape out of a model before I slice it. I only use the slice method to cut because I see no other way to do it. So its 2 slices, 1 to cut out the cube, and a second to apply supports but they are blocked by the blocker. 

 

I don't understand why i can't remove the blocker after the slice to leave the finished product I need so I can slice it a second time with supports. I just hate to reimport an STL out of another application because I find there  can sometimes be issues. 

Edited March 2, 2023 by dougeldridge01

[GregValiant 1,251]

Cura is not a CAD program.  The block does not "cut" the  model, it just tells the slicing engine that anything inside the block is to be treated differently.  The model itself is not changed.

 

Load the model in Cura and use the "File | Save Project" command and post the resultant 3mf file here.  If you have a model with the weight in place and can pass that file along as well that would give me a better idea of what you are shooting for.

[dougeldridge01 0]

And thats a fair statement. 

 

WeightTesting1 is the master file.

 

Weighttest4 is the block to remove.

 

PI3MK3M_Master-Scaleup-Multiple-Scaledown-WeightTesting1.3mf PI3MK3M_Master-Scaleup-Multiple-Scaledown-Block-Weightcut4.3mf

[GregValiant 1,251]

I'm guessing over here.

Box with a cavity.stl

[dougeldridge01 0]

@GregValiant That's exactly it! How did you remove the blocker?

[GregValiant 1,251]

I didn't.  That's your first model without the blocker.  I measured the cavity you wanted, opened the model file in MS 3D Builder, brought in a cube, sized it, located it, and subtracted it.  It's the sort of thing you need to do to give Cura the model you want rather than "this is almost it except..." which rarely works out well.

 

Cura is good when changes you want to make are in regards to slicing.  It's poor when you ask it to do CAD work.  It's just not what it was built to do.  I like MS 3D Builder.  It's good at modifying STL files but as I said, it's not very intuitive so some things take a bit of trial and error.  Actually, in some cases things take a LOT of trial and error.  I struggle mightily when I want to put sunken lettering on a model and it's something I've done a number of times.

[dougeldridge01 0]

hmm

Edited March 3, 2023 by dougeldridge01

[dougeldridge01 0]

@GregValiant Thanks for the tips Greg, I am trying the MS3d way. Question, when I place a cube and resize it, how do I then delete? When I place my model in another model to make a hole, subtract is greyed out. 

meshtest.stl

Edited March 31, 2023 by dougeldridge01
add image

[GregValiant 1,251]

It may be because of that red square around your model.  That is the MS3D indicator that the model has errors.  When you open the STL in Builder and then use the Insert tool, a dialog should come up (in the lower right) to inform you of errors.  Clicking on the dialog will start the repair tool.  It worked on your model.

MS3D Builder doesn't tell you what or where the errors are.  Here is the model in Mesh Mixer.  The magenta and red balls indicate the errors in the model.  Mesh Mixer also has a repair tool but I've found it to give "unexpected results" so I prefer MS3D Builder for repairs.

 

Here is the repaired model with that window removed.  The "Subtract" tool was available with the repaired model.

[dougeldridge01 0]

Thanks Greg, during my TS I figured as much. Ultimately, I found MS 3d Builder to not really have enough of a community/support so I went with blender and this tutorial. I wanted to take one last moment to thank you for your help, you helped me to think differently and I appreciate it very much man. 

 . 

[GregValiant 1,251]

Whatever software you choose is fine.  There is always a learning curve.

I've been sticking with Builder because I have confidence that the edits I make result in a "watertight" model.  If Builder had "fillet" and "chamfer" tools it would be better (but probably still non-intuitive).

[dougeldridge01 0]

Yea one tool never really seems to have everything. If you are into 3d modeling it seems you just need to get experience with a few tools. Slicer + Modeler. 

 

Again, thanks for your help. Have a good one bud.