Calculated Volume Bug?

The reason why I chose to go with a Form 2 instead of the alternatives (including building my own SLA printer) is I thought Formlabs had the most professional software.

But the first thing I want to print shows the volume to be only 34.02 mL. There is no way this can be correct.

Calculating the volume accurately is an important aspect of having a pro workflow, so this is a serious issue to me. Is this where we file bugs?

I am using PreForm 2.5.0 but the same issue was apparent with 2.4.1.

Your mesh does not look like it’s solid, though it’s hard to tell.

According to other software it is a watertight solid model. Despite that, PreForm asked me if I wanted to repair the model. I choose yes, and no errors were reported.

It actually has numerous shells, but I think having manifold bodies inside manifold bodies should be valid printable geometry.

I guess what is most alarming, is PreForm didn’t report any errors and clearly something is not correct.

The mesh might be too far gone for it to fix, but it’s really hard to tell-like I said it’s really complex so I can’t tell what it actually looks like. There’s some shading which could be an issue with flipped faces or it could be z-fighting with the faces too close together.

Can you take a screen shot with the layer slice around 500 - 700. This will show us what the inside of your model looks like and how thick the wall is (assuming it is hollow).

Here you are.

Based upon your picture, your model is not a single solid. I believe each separate piece is being seen as a solid (maybe). If you post up (if you are willing to share) the .stl, some of us can take a closer look.
Another test to prove my theory, generate supports for the part. I believe the model will be littered with internal supports.

Re-reading your post, I think your problem is “It actually has numerous shells, but I think having manifold bodies inside manifold bodies should be valid printable geometry” You want 1 solid model or 1 solid shelled model. Not many manifold bodies. From my experience, you will not be able to print this part as it stands. It is not a problem with PreForm but a geometry issue.
I understand you think it should be valid printable geometry, I believe you are incorrect.

So you are suggesting it isn’t possible to print a part within a part?

For instance, one could not print a chain link on the form? Or a printable ball bearing? Those are parts with more than one valid shell.

Also, my issue is that it doesn’t report its not a valid geometry and instead reports a incorrect volume. It acts like it “fixed” it and is ready to print. How do I know for other parts that the volume reported is in-fact correct and not due to some unsupported geometry?

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Yes, a chain can be printed. Maybe a ball bearing. I think someone here tried it. I do not know if it was successful. Your model is not a chain or a ball bearing. I should have been more thorough with my response.

What does your cad software say the volume of the part is? If you feel the part should be printable, give it a try. I would not print it as I do not believe it would be successful based upon the 2 images you provided.

I would open a support ticket and send FL the file. They can tell you more about the embedded repair tool and how it is configured to repair models.

Of course my model isn’t a chain or a ball bearing. My point is those types of geometries have more than one shell - that aren’t connected which is the same as this part.

It was not created with CAD software so I couldn’t tell you. I guess it is about a liter though.

Thanks I guess I will do as you suggest. Again - my concern is how do I know when to trust the volume or not and if it is a valid geometry or not if PreForm reports that everything is fine. Seems like cause for concern.

Something is wrong with that geometry. The light blue chunk in the back and the dark blue chunk in the front indicate that something is amiss. I suspect that as you flip through the layers you will find that fill line jump around. I agree it probably should be something PreForm should catch.

Yeah - the blue does flip around.

I thought this model was a solid, but I actually loaded the wrong version (I have many of them). Meshmixer is able to repair this geometry and then it comes into PreForm fine. I hate having to rely on free unsupported software however, and I still am concerned PreForm didn’t report any issues. Just let me know if you might like me to test or beta test anything of if I can do anything to help.

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