Multiple faces: invisible but not suitable for 3d printing!
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I noticed that sometimes, in complex models, if I join two points by a segment ending in creating a triangle, automatically the triangle is filled... but rather than by one face, it's filled with multilple faces: more often "just" 3 or 4 faces, but in a specific situation I kept deleting and deleting and deleting the face until I counted 10 of them!
They are totally invisible in normal view, but they are barely visible in X-Ray view as they appear in different color (lighter or darker, depending on.. who knows?).
Is there any plugin capable of automatically removing all of these spurious faces?
They are also visible by importing the STL into Netfabb, but it's quite uncomfortable if you have dozens of multiple faces... -
Do you have an example file with those multiple faces?
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Thomthom's "Solid Inspector" will show up the problem faces.
My "SolidSolver" might fix such issues.
The problem with fixing these kinds of thing 'automatically' is that one false step/assumption early on and then what you end up with might be a solid... BUT with massive lumps missing !
You can be try an see what happens...
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See attached file.
I higlighted faces with different colors, but they are usually all same color and then invisible until you delete them.
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No they are not.
Fine for me...
Perhaps you have a graphics-card issue try different settings in the SketchUp Preferences > OpenGL dialog...
View > Hidden Geometry ON to see surface smoothing edges.
Incidentally, the SKP you posted is a single thickness 'surface' skin, with no 3d volume, so it is unsuited to 3d printing without some additional work
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Tig, if I delete the yellow face a blue face appears behind it.
If that doesn't happen on your system then there is certainly something different happening here. -
OK I didn't get to that face...
Indeed the form does have some overlaid faces, which is an issue that has been reported before.
Two coplanar faces with exactly matching edges shouldn't be able to occupy the same space - but sometimes they do.
The object is very small and facetted.
Try scaling up to do such fine work.
Very small geometry can cause issues...
Viewing in Xray mode might also reveal the overlapping faces.
Try doing a select all, group and immediately explode the group - that jogs it into seeing sense.
Removing duplicated faces.
An alternative way is to make the group and then copy it snapping exactly onto the original.
Now edit one of the groups, select all and context-menu 'intersect with model'.
This will also jolt the geometry in the group you are editing - with the four duplicate faces will merge...Incidentally, a Statistics > Fix does nothing
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So by this discussion should I assume that one needs to be modeling with solids to output to 3D printing?
I'm modeling large scale locomotive models to be outputted to 3D printing and laser cutting.
Should I be modeling with solids? Which I assume also means upgrading to Pro?
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I only posted a small part of my model, just to let you see the multifaces issue.
I know how to fix them by hand, but after fixing the 100th face I'm a bit tired... and every time I make a little change to the model, faces mess up and get duplicated!
I'm now experimenting with the suggested plugin.Jaxcoffee, Sketchup Free is perfectly suitable to create printable models, I already created and printed a dozen of models; most printing services require STL format, so you need an STL export plugin,but Sculpteo accepts .skp files.
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The suggested plugin works quite well, but it does not detect all defects detected by netfabb (it misses some holes).
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Another plugin I have used to help making solid objects is CleanUp; it gets rid of any extra geometry or duplicated faces.
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The geometry in the model you attached is quite small, scaling up would certainly help with fixing problems caused by tiny faces.
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@box said:
The geometry in the model you attached is quite small, scaling up would certainly help with fixing problems caused by tiny faces.
I already read about this, but I don't unserstand why SU cares about dimensions; but I just discovered the option to set precision down to 1/1000th mm, maybe it depends on this?
Anyway I found another weird behaviour: i was trying to copy&paste a part of my model, because it has a lot of multiple faces which both Solid Inspector and CleanUp can't manage, to post it to the forum.... but once I pasted the part to a new file, multiple faces disappeared!!
And that's not all: CleanUp actually works, but it's not aware of it! I mean, if i select the area containing the multiple faces and I start CleanUp, it ends with the statistics dialog which says that nothing has been fixed, but that's not true: multiple faces have actually been removed!Finally, I am not even able to paint each face in different color to better show them to you, as they don't get any color, they just remain white.
Maybe it's better if I upload the full model...
I had to remove most part of the model because I have upload limits from office: to prevent "mysterious auto-fix" I deleted useless parts rather than copy&pasting useful parts into a new model.
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@jumpjack said:
I already read about this, but I don't unserstand why SU cares about dimensions; but I just discovered the option to set precision down to 1/1000th mm, maybe it depends on this?
If I scale your model up with factor 100, all double faces are gone...
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Sketchup doesn't like creating tiny or huge faces. They can exist but it has problems creating them. Your model is Tiny, scale it up and your problems will go away. Scale it back down when you are finished. Or work in meters then scale it down to millimeters when you have finished.
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The tiny facets failing to form issue is down to SketchUp's built-in tolerance.
Every modeling application must have such settings, because calculating the numbers used for points will inevitably result in some numbers that are not exactly identical BUT ought to be considered identical. Otherwise you'd snap to a vertex and the application would recognize the existing vertex point and the snapped point as being almost identical, but not quite, if there even a zillionth of an inch difference in one value from the Maths...
So the tolerance used is a thousandth of an inch.
SketchUp works in inches even when the Model Units are say mm.
The 'displayed units' are just for user's convenience.
Edges less that ~0.25mm will therefore often fail to form as the two vertices forming the tiny edge's ends are deemed to be coincident, and you can't make a 0 length line ! Without the missing edge a face can't get made because it needs a continuous loop and the tiny gap thwarts that !
I expect that 1/1000" was chosen because SketchUp is intended for modeling buildings and their parts, furniture etc, and 1/1000" is far more accurate that you'll ever need.
With the advent of 3d printing and related solid-modeling many parts are smaller, and/or modeled to an accuracy that was never originally envisaged when SketchUp was first developed.
Therefore, if you model at x100 or x1000 you should avoid the tiny face issue.
Set your Model Units to meters, at 3dp without any length snapping or unit display set.
Now model.... typing in 10 as if it were mm, when it's actually 10m...
Never add a units suffix to your input.
When your modeling is finished and saved, draw a line 10 long, then use the tapemeasure tool and pick the two ends of that line, the VCB says 10.000, immediately type 10mm [note the units suffix mm]... and answer Yes when asked if you want to scale the model. It now shrinks by 1/1000 - Change your Model Units to mm. All really tiny facets will continue to exist; as was said they can exist it's their initial creation that is the issue.
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