Number of segments in arc or circles



I use Sketchup to make drawings that I export as a dxf-file for a CNC machine. These drawings contain multiple arcs in various radiuses from 2mm to 30mm.
In Sketchup pro 2015 I can have 100 segments in a 90 arc with 2 mm radius no problem, but in Sketchup 2017 I can only use 9 segments else I get” number of segments is too large for given angle and radius sketchup”. When I use these drawings in the CNC each segment becomes visible instead of making a smooth arc and it’s very frustrating.
Is Sketchup 2017 limited in the arc and circle segment numbers? Can I do anything to make Sketchup 2017 accept more segments?


Export as 3d dxf and you will get perfect circles.


I have the same problem. :neutral_face:


Then use Box’s instruction.


Two details I want to point out:

  • SketchUp’s segmented circles will export as true circles in 3D dxf/dwg provided they have not been edited in a way that causes SketchUp to abandon the metadata about the original circle. You can tell whether this is the case by clicking the circle/arc with the selection tool and seeing whether entity info says you have selected a circle/arc or just selected an edge.

  • Your model does not have to have depth to export it as 3D; you can draw on a plane (2D) and it will export as a planar shape the same as it was in SketchUp.


Problem whit 3D export is that all the layers from the Sketchup model will export as well, and if there is some tiny error in the drawing showing up in the CNC program I cannot rectify them in the CNC program.

The CNC program cannot deal whit multiple layers even if they are hidden. When you use the 2D export only the visible layers are exported and everything works, except that there are too few segments in the arcs and circles.

I realize that I can save one layer in a different model before 3D export but that will double my already overwhelming number of models.

But honestly… Why should Shetchup be so sensitive about the numbers of segments in 2017 and not at all in 2015? there must be some way of telling Sketchup 2017 not to be so sensitive. I mean its super annoying to try to find the maximum numbers of segments allowed in each different arc or circle. Especially when trying whit to many segments results in the arc disappearing at once.


The intent is to head off the problems people created for themselves by making segments too short. Simple example: Run Follow Me to create a sphere in the attached file.
Sphere.skp (26.0 KB)


This was a change in su2017 as noted by Dave, The changes are :slight_smile:
“Fixed an issue with the Circle/Polygon tools in which they could snap to axis inferences that didn’t exist when off axis.
Fixed an issue with the Circle/Polygon tools in which they seemed to disappear during drawing and couldn’t be completed when the radius was aligned with the axis normal to the circle/polygon.
Added error checking when entering number of segments in the VCB (Measurements toolbar) for Arcs/Circles/Polygons.”


I, too, have been frustrated by this change. I’m designing micro-scale models for export to COLLADA or STL for 3D printing. Currently, I’m working on a 1/87 Swedish CV90 armored vehicle for a museum in Switzerland and I have to be able to make small curved segments (.25mm). I never had problems doing this using the Arc tool in any previous version of SU, which I’ve been using since 2011, but with this new change, I now have no way of creating new segments.

Now, it’s true that I can make the model 5x or 10x larger and then reduce it, but then I’m having to do running mental tallies of various objects to ensure the model can still meet the 3D printer’s minimum resolution. I’m curious why what used to be possible is no longer allowed? Was this a solution in search of a problem? It would be nice if the devs could provide some transparency around the types of problems people were experiencing.


If you had spent as many hours as the Sages have here helping people understand why they were getting holes and missing edge segments in their small models, you would welcome this change. Yes, in older versions you could draw small arcs and circles with large numbers of segments but more often than not those tiny little segments created issues that resulted in groups and components not being watertight.

Even if you could still use larger number of sides on arcs and circles, you’d have to scale up at some point to avoid the gaps, anyway. There’s no change to that.


I’m sure your experience here has been such. But your supposition about my point of view is deeply flawed. Why would I welcome a change that removed entirely a feature that worked just fine for me for the last five years, and without which my job becomes just that much more difficult?

From my perspective, here is what happened in this version of SU:

  • There was a function that worked fine for me for years.
  • Some people had troubles with that function, or it messed up their designs.
  • Trimble didn’t fix the function; they just took it away.
  • Now I have to waste my time with a workaround.

Yep. This is the kind of thing I feared would happen when Google sold SU to Trimble. First, they eliminated the ability to dock the large toolbar to the bottom of the screen for no explicable reason. Now they’re starting to trim away functions rather than improve the software. I see a pattern of Timble’s designers putting their convenience over the end-users’ needs. It feels more and more like I need to look for a different design suite.


Yes but it would not be a problem at all if I could CHOSE if I wanted these simple arcs when I’m using the follow me tool. or if I wanted to use ahellofalot of segments when I need to. I mean it could just be an ignore button in the error message or some way of shutting it of in a menu somewhere. It seems very bad to cut the usability of a program this severely.


This depends on how you look at it.
You’ll now have to go through SketchUp’s “warning sysrem”.
It seems too many people lost (chunks of) geometry in the past with ‘Follow Me’ and some other operations, getting confused what happened with their model.
You can still create small geometry in the range of edges of 0.05mm (just did) including creating faces. In the end it can even be raw geometry.
Like in the past, components and scaling up/down are involved.
The confusion for new users might now be: can SketchUp create small 3D printable objects with “smooth” surfaces. Yes, like in previous versions.


Have tried various choices in the options menu, and STILL get segments, as well as taking a minute or two or 5-10 minutes depending on size to bring the file into enroute 5. Part of the file is on the layout sheet at 0/0, the rest is up to a couple hundred feet off to the right. Actually, after this last test of a normal sized file of some counter tops and cabinet pieces, it is still trying to be brought into enroute. So far appr 25 minutes. NOT a useable way to bring files in so I can set them up for cutting.
It will also cause the radiuses to disconnect and move from its corner and rotate 90 degrees so that the top of the arc is now at the bottom connection point, at least at the lower left corner, the rest do similar for their location.
Now if I do do a standard circle and a line, arc, line, box they will smooth if left in 2d, but once you push/pull, it will now come thru smoothed, but with little triangles at all the segment points.
Really wish had left it as an option so that the person drawing could make the choice to keep it as 2016 version instead of completely taking it out and causing more headaches and problems for quite a few people from what am seeing here. And you also have to wonder how many are not, or cannot say anything because not logged in here.
It still goes back to the real pain and time loss of having to guess how many arcs can be put into an arc or circle depending on the situation, because it can take multiple attempts to get the number that will fit.


An update on importing the 3D export from sketchup 2017 to enroute 5.1. I am not sure exactly how ling it took to complete the import process, but I do know it was over 30 minutes for this file.
As you can notice in the one photo, the dotted lines run from the selected counter top all the way over to the cabinet at 0/0. In the other photo, you can also see how far it is displaced from the original plate at 0/0. Yes it looks like it takes the segments out, but still have a lot of cleanup work to do before usable. At this point it is easier and less time consuming to bring in the segmented file in 2d and clean up in Enroute.
This is a fairly small file to what might normally have. With this test it shows that importing in 3D mode would be too time consuming and not worth doing. Taking out the feature of having the capability to specify the number of segments has limited quite a few people I suspect and made it harder to use.


This is the other file mentioned in previous reply.