Is it a problem that a circle/arc gets segmented on a model?

Hi everybody.

I’d like to know if it suposses some problem to get a circle or an arc segmented after intersecting it with a line or another shape because I think it’s good to make corrections when the model is still simple before it goes further.

Once it’s get segmented it’s hard to select the part you want, you finish sooner if you select all and deselect what you don’t want into the selection, that’s why I tried to avoid it and so far I’ve been redrawing some circles that get segmented after drawing some lines that intersect or touch the circle/arc.

But now working on 3D I get the same problem.

Thanks in advance.

This is something like my workaround, but not always work as I expect, as you can see in the video for the second circle it keeps still segmented.

It isn’t normally a problem but you could use TIG Weld or another of several plugins to weld the edges together. If you don’t want to use a plugin, you can use a different method to draw the part and skip using the Solid Tools.

What is the radius of circle?

1 Like

I noticed while I was doing this model:

Now I only have the final result: Solido09.skp (145.6 KB)

But I can also propose an example with 15 as radius.
Untitled.skp (35.0 KB)

If it creates a problem for you, use a different method. I drew it without the use of any Solid Tools and no Intersect Faces, either.

Thank you DaveR.

I get the idea of drawing it without using solid tools nor intersecting faces.

My real care is to know if a circle or an arc divided on segments means that the model has a poor design.
I keep with your first reply in mind, “it shouldn’t be a problem”.

You can do it this way too. Segment does not occur.


Good point ecati.

But if I’d finish a model with arcs and circles divided on segments would mean it’s a poor design?

Are models from people who make a living using SU free of arcs and circles divided on segments?


PS: would it affect to a 3d model printed?

The short answer is “No.” If you are exporting to STL for 3D printing, the circles and arcs will be converted to segments anyway. However, what looks very smooth in SketchUp may look very faceted when printed. To minimize the faceting, you need to use about 64 segments for a 20mm radius … the 5mm radius hole would need about half as many (i.e., 32 segments). You can use a higher number of segments, but the printed result will not be noticeably different due to the resolution of the printers.

1 Like

Thank you jimhami42

Do you know if it’s usual to find arcs and circles converted to segments in models made by people who make a living from the 3D design using SketchUP?

It’s not just SketchUp … STL reduces everything to triangles. No curves. This picture from WIkipedia shows the effect of the approximation:


1 Like

There are several ways of making the form so all arcs/circles are kept, some ways were already demonstrated.
Another would be to make the two end full cylinders, divide an inner face, then pushpull it onto the other cylinder, then erase the unwanted arc on the surface which in the process also removes the inner partition, this way all arcs.circles are kept intact.

1 Like

TIG, your explanations are great as usual.

It’s good to know several ways I can approach that result, but in this case was only an example.

My worry is if I should always to find the way to prevent my circles and arcs get segmented.
Does a final model with arcs and circles segmented means it’s a poor design that belongs to a bad designer?

I use SketchUP as a hobbiest, I’m not looking further, but who knows?, I prefer to know the right way to work with this program to avoid problems in a future, because if I get used to do it in certain way and I’m wrong, I will have to get used to do it in different way from scratch.

It’s a problem only if you later need to do something that relies on SketchUp recognizing the segments as belonging to a single thing . Circles, arcs, and curves are always series of edges in SketchUp. What’s happening is just that it has lost the metadata that remembers that the series represents an arc , circle, or curve. The geometry of the model is itself not changed.

Yeah, but for example, when it gets segmented I think it’s hard to find the center (in a circle should be easy with tape measure and dividing the diameter by 2). And you maybe want to know what radius has an arc, with dimensions tool you can know it, but if it’s segmented you cannot.

That’s the kind of thing @slbaumgartner was talking about. The segmenting is only a problem when you need SketchUp to recognize the series of segments as a circle or an arc. SketchUp won’t recognize there is a center if the curve is not an arc or circle.

That said, there are easy ways to find the center or an exploded arc or circle if you need to do that. And there are nearly always ways to create your model without exploding arcs or circles.

Thank you all, sorry for bothering so much :slight_smile:
I guess we can consider this topic over.

This topic was automatically closed 91 days after the last reply. New replies are no longer allowed.