In the attached model, I have a curved tube running down the back. It has an opening on the front/top and at the bottom. Shapeways doesn't have a problem with the STL of this, except it seals the bottom opening (see below). Any ideas why and how I can keep it open?

Your object is not a manifold solid. It is a joined surface. Shapeways probably fixed the non-manifold issue by closing off that hole.

Do you remember seeing anything about non-manifold or "fixing" when you uploaded your model?

Here's a video where I make your object a solid. If you do this it should print fine.



So just to be clear, I selected only that surface. Then I ran SelectNakedEdges and chose loft (Without Caps), then joined the 2 parts to a solid.

Thanks loads for making this video, BurrMan! Unfortunately, we may be on different versions of MoI as I have a Browser, but not a Scene Browser (plus my command icons are grayscale while yours are in color, and I don't have anything after History under my Edit command, among other UI differences). I'm on 3.0, 9-18-14. Anyway, I try to follow along but I still end up with a joined surface instead of a solid. I've included the updated model (Shapeways didn't indicate there was a problem when I uploaded it, though it can't produce it in every material), but if you can give me some pointers on how to locate areas that prevent a model from being a manifold solid I'll try to fix it myself.

PS - Sorry for the delayed reply. Even though I subscribe to this and other threads, I never receive notifications of other posts.

Hi Involute, the main way to find out where your object is open is to set up a shortcut key which will select naked edges, see here:
http://moi3d.com/forum/index.php?webtag=MOI&msg=6051.2

If you do that on your model you should see 2 edges highlight down here:


There isn't any "side wall" for the hole there you'll need to build one. A quick way to do that is with the 2 edges selected run Construct > Loft and uncheck the "Cap ends" option before you finish the Loft command. That will build a cylinder surface between the edges, select that and your main object and use Edit > Join and you should then have a closed solid.

- Michael

Hi Involute,
"""""We're on different versions""""""

No. Pay no attention to that stuff. They are just ui customizations. Nothing needed on your part, except the "SelectNakedEdges" script. Michael posted about it and where to get it and set it up.

If you run into issues after that, post back and can get more detailed.

That fixed it. Thanks, Michael (and, again, Burr Man).

I spoke too soon. After initially accepting the STL Shapeways later identified some thin walls. Some I was able to fix but not the ones in FilletProblem.jpg (below). I tried the fillet tool but it never stops calculating (using a variety of radii). I've tried subtracting and merging things from/with these edges, but that just creates other problems. Suggestions?



On a possibly related note (related to the initial question of this thread), I'd like to make a tunnel between the two rectangles in LoftProblem.jpg (below), on the top and bottom of the plate they're on, but when I loft between them there's no opening created (though the outlines of the loft are visible inside the solid being lofted through). I try selecting the interior of each rectangle to delete it, but it's not isolated from the plate. Since they're offset, loft seemed like the easiest (only?) way to do it. What am I doing wrong? Thanks for all your help.

Hi Involute, for your second part:

> On a possibly related note (related to the initial question of this thread), I'd like to make a tunnel
> between the two rectangles in LoftProblem.jpg (below), on the top and bottom of the plate they're
> on, but when I loft between them there's no opening created <....>

That's because Loft does not make openings, it makes surfaces or solids. To make an opening you'll need to use boolean difference after doing the loft.

Select your main object by itself first then run boolean difference then the tricky part is to select the lofted solid as the cutting object.

There are a couple of different ways to do that, you can do it with a click if you get the click right on a zone where the loft happens to be showing over top of the main object, or a couple of less finicky ways are to use Window select (click in empty space and drag a rectangle, preferably starting from left and going towards the right to get a "only contained inside" selection rectangle, also it's a good idea to have deleted your rectangles after building the loft so you don't accidentally select those as well since 2D curves can also be used as cutting objects but they will cut straight through), or another thing you can do is in boolean difference when it is asking you to select the cutting object you can push the Edit > Hide button right then without the command exiting and it will hide the main object so you can more easily see and click on the lofted result.

Also with the window selection method if there is not any good empty spot to click on to begin the window drag you can hold down shift+ctrl when you click that will force a selection window to happen right away.

Let me know if any of this is unclear and I can make a demo video.

- Michael

I should have said I tried boolean difference, but couldn't figure out how to select the loft. I got the Windows select to work, though, so that's solved. Thanks.

What about the fillet? ;-)

For your too-thin-wall problem, just to make sure I understand is it this area here that is too thin? :





For putting in a fillet there, it seems to work ok for me but note that this length here is only 0.007 units:




So only a quite small fillet will fit in there, here's an example filleting both longer edges using a radius of 0.003 :



Is that going to be enough to solve it though or do you really need something like moving this entire face inwards a ways:



If so then by what distance? The length on the bottom part here is only about 0.045 long:



so there isn't a whole lot of space to move back by but maybe some?

- Michael

And for the "move face" part, that was accidentally a diagonal line I measured by, there's more like 0.025 straight distance available there.

- Michael

That's the right face. I tried the fillet and got it to work (didn't think to try one so small (feature request: find largest possible fillet)), but Shapeways is still rejecting those edges. They require .028" minimum wall thickness, but it's hard to translate a corner into a wall thickness. I'm happy to push the face back .025" (based on their render that looks like it may be enough), or as far as it needs to go.

Hi Involute, so I pushed it back this far (as seen from the Top view), so that it wouldn't leave any really tiny piece sticking out. That's a distance of about 0.0219 units:



3DM file is attached. The process of pushing it back doesn't take long but there are a few tricks to do it quickly - I first drew in a line in the top view for the new end position. Then I selected the top face and 3 side wall faces and use boolean difference to cut them. You can do a boolean with face sub-objects selected and that causes the boolean to only cut those selected faces ignoring all others. That cut the object up as needed and left some excess faces to be deleted. Then to cut the new vertical wall I had to extract out the large grounding face below it and do an "untrim" on it (select all of its edges by selecting 1 and doing Ctrl+A for select all then using delete), then I trimmed the new vertical wall with that, joined the vertical wall to the others, and then retrimmed the ground against all naked edges then rejoined, repeat that for each side. Let me know if you want more details on this.

The new face is 0.0278 units wide, hopefully it's enough since it is a corner type area and expands from there, not exactly a wall thickness.

- Michael

Thanks for doing all this, Michael; I know you're busy and I really appreciate it. Hopefully I'll become self-sufficient soon. ;-) I uploaded your model to Shapeways and it passes now. In the meantime, I'd like to learn how to do this myself, but I only got as far as, "repeat that for each side." Not sure how to do that. I'm still left with the triangular hole in the ground surface.

Hi Involute, you're welcome and I'm glad it passes now!

Later tonight I'll send some more details on how to fill the triangular area, but real quick for now the key thing is that it is done using an "untrim" followed by an Edit > Trim. There is some info on untrim here: http://moi3d.com/forum/index.php?webtag=MOI&msg=444.4 and also in the object repair tutorial here: http://www.moi3d.com/forum/index.php?webtag=MOI&msg=446.17

You have to use Edit > Separate on the "ground" face first to break it off into an individual surface, after that you can do the untrim by selecting all of its edges (quick way to select all edges of a surface is to select one edge to start with and then use Ctrl+A for "Select All") and hitting Delete. That will remove the trim boundaries and recover the full original "underlying surface" of the face which is a big sphere. Then it has to be retrimmed.

Also one other quick note for now - it looks like you put in a line here to make the new vertical plane:


That won't be quite right because the "ground" face is curved, so instead you want that new vertical plane to initially stick downwards a ways so it pushes through the ground then use Edit > Trim on it using the ground as the cutting object. Once you have trimmed that vertical plane with the ground you'll then have all the edges to retrim the ground sphere, there are 19 edges that the sphere needs to be trimmed against but they are all naked edges so in the Edit > Trim command you can use the "Select naked edges" shortcut key to select all the needed ones rather than going around and selecting them with individual clicks. Once the "ground" sphere is retrimmed you then use Edit > Join to glue it back in place.

I can give you some images later tonight to explain it better.

- Michael

Thanks for the additional details, Michael. I was able to follow your instructions, push the faces back, and get a solid acceptable to Shapeways.

Sounds good Involute! Please let me know if you would like any more details on any of those steps.

- Michael

Impressive how you figured out the problem and gave a very detailed instruction! I wouldn't have been able to sort that out