Spheres and cilinders

Hello everyone,


This is my first post. I've been following Shapeways awesome technology for some time and I'd like to try a project of my own. Please bear in mind that I am very new to this.

I'm using Sketchup to create a model connecting spheres together using cilinders. But the model does not make a solid object. I use a nice little plugin called Solid Inspector that shows some problems with the model, but I don't know how to solve them reliably.

I think the spheres and the cilinders are not really wireframe objects (does that make sense?). Does anyone know a tutorial that shows how to transform a curved object into wireframe so that I can fix faces? I seem to be able to fix some faces of the spheres by drawing vertices, but then when I look at the object as a whole, there are a number of lines drawn onto the surface of the spheres and cilinders. It doesn't look right and it doesn't solve all the problems Solid Inspector points out.

I did look for tutorials and threads concerning spheres, on this forum, on Google and on YouTube, but without succes. Since I see quite a lot of people developing beautiful curved objects on this site, I thought this might be a classic beginner issue. Can someone help?


Thanks in advance. Best regards,

X

What exactly you mean by saying "wireframe objects"? I can think of the following by now:
1. You have a 3d model in Sketchup and you don't know how to view it in wireframe mode. (most 3D software offer the ability to view the same model in wireframe mode, solid mode and texture mode)
2. Your 3D model's structure looks like it is consisted of a many solid wires, but it is not printable yet.

Do you have a screenshot?

Hey TF, thanks for your reply.


It's none of your suggestions. It's as if I can see that some of the spheres are not a single unit. Some discoloration shows that the sphere is probably not in one piece. If I double-click it, it shows a wireframe-like structure. But I think those dotted lines are only an aproximation of the smooth object.

I created all the spheres the same way: using a vertical arc and the follow-me tool on a horizontal circle. I deleted the circle afterwards. Those lines "happened" later, when some of the cilinders intersected with the spheres. What is strange, is that not all the spheres have the same amount of sections. Some have none at all.

I should have thought of that.

This image shows a difference between the bottom sphere, that is completely smooth, and the right sphere where several grey shades suggest that it is made out of different pieces. (I hope you can see that) :

View attachment Broken spheres.bmp

Someone PMed me and suggested to select some of the objects and use the <intersect with model> command. This was the result:

View attachment Intersections.bmp

(No worries, I saved different stages of the project, so I can go back to the previous states).

When I use the <Solid Inspect> plugin command, it still shows problems. And some of them at the lines visible in screenshot 2.

When I'll send in my project, I'd like the cilinders and the spheres to be full solid. And connected of course.

Try using this plugin. https://extensions.sketchup.com/en/content/cleanup³
It looks like you have faces on top of each other

If you have finished with your design you can do the following:
1. Export your model as an .obj file and import it to MeshLab (it is free)
2. Once your model is loaded in MeshLab, export it as .stl and import it to netfabb (it is also free, you will need to wait 10 sec before it starts. Otherwise you can buy it so to start immediately)
3. Repair the model in netfaab.
4. Export the model as .stl again and you 're done.

As you first draw a shape in Sketchup, you have the option of setting the number of facets (sides) around the circle. The default is often eight facets/circle, which is not near good enough for 3d printing. Unfortunately, you must set that for each circle/cylinder/sphere, and you must set it before you draw the object, not after. You only have the one chance to change it.

Select one of the tools circle/cylinder/sphere and look at the bottom right corner of the screen. There, you can set the number of "Sides".

Thanks to everyone for replying so quickly. I tried all your suggestions, but I ran in more problems than solutions. :-7

I installed the plugin, and it fixed a number of errors. However I still have the partial domes.

I searched for a .obj exporter, but none worked (for my model) to be able to import into Meshlab. However, I found a .stl exporter for SketchUp and used that instead. I loaded it into netfabb and tried the analyse and repair commands. The analyse found errors, but I often get an Access Violation error. After I aplied the repairs, my model was gone. I tried several times and each time I lost it. I don't understand.

The default in Sketchup 13 seems to be 24 facets, but a blog somewhere suggested to set it to 96. When I tried it, my spheres had a hole in the top and the bottom. Another google search tought me that SketchUp doesn't draw vertices when they are too close to each other. Apparently for a model of about 10cm high, 24 should be good.

Another blog about 3D printing suggest to design my model in larger scale and then downscaling it to the right size. It is actually something I did unbeknownst, since my project is a scale model of a 102m tall building. I'm not sure, but I think my problem started after the downscaling. Is this an indication?

I don't mind starting over the entire project, but I need to learn as much as possible before I start again. Any suggestion would be really appreciated.

Thanks again for all your input.

X

If you want something 10cm in size to be truly "round", you need a LOT more facets than just 24.
For the FUD material at 10mm, I use 128 facets if not 256.. you'd want "a few more", like 1024.
But, you also have to be wary of the million triangle limit.

Read this: https://stonysmith.com/wired/scaling.asp

==
Since I'm doing miniatures, I personally design my models to decimal feet.. that way I can take a tape measure out and actually measure the physical object. Then, as a last step before uploading to Shapeways, I multiply by a factor to get the model to the right (printer) size and upload the file as millimeters.
Most of my models are at 1:220 scale, so I use a factor of 1.385.

(feet * 12) * 25.4 / 220 gives 1.385

I built this little calculator:
https://www.stonysmith.com/wired/ScaleFactors.asp

Well, the entire model is 10cm tall, but each of the nine spheres is perhaps about 1cm in diameter. And in fact the circle I use to guide the follow-me tool has 24 facets. The arc has 12. So in total each sphere has 576 facets.

However, I tried setting them to 32 and 16 respectively, and SketchUp seems to accept it.

I did. Very interesting, thanks.

One more question, if you don't mind: on your Grant 4-4-0 Locomotive, how did you connect the chimney to the fuselage? If you didn't use SketchUp, how would you do it if you had to?

Have you tried the 'Outer Shell' command?
Make sure that each sphere and cylinder are either a group or a component.
Then under Tools - Outer Shell - Pick a shape the cursor should show (1) a small pop up will appear saying 'Solid Group' pick another shape, this will show (2). So long as they are overlapping each other the two shapes will be joined as one. Creating a proper intersection and deleting all of the internal geometry.
If the shapes are not solid a warning circle will appear with a pop up saying 'Not a Solid'
I have shown hidden lines in the image to see the facets of the model. This is under View - Hidden Geometry.

To solve this problem, double click the sphere to edit it, draw a line across the hole. A face will be created, delete the line just drawn. Do the same for the other hole. It will now be solid.

I followed your guidelines as to the facets and rescaling, stonysmith.
I used the Outer Shell tool as you suggested, JACANT.

And it worked! Woohoo!

I double checked with Cleanup, uploaded the model to Shapeways and it passed all checks with flying colors! (or at least with flying monochrome grey). ;-)

Ok, I'm about to order the part in White Polished Strong & Flexible Plastic. Any last minute tips before I give the go?