Finding the top-center of a cylindrical-hole using the Dimensioning-tool

If I create a simple rectangular board and then create a cylindrical hole through the board, I can use the “Dimensioning Tool” to; first touch the outer circumference, then move to select the center, and move again to the edge to label the dimension of the center of the hole to the edge. So far no problem. However, if I recall and older, similar drawing an try to do the same thing, this time when I use the “Dimensioning Tool” it is not able to touch on the circumference of the cylinder top - only the end points of each segment comprising the circle and therefore it can’t find the center. Why has the older drawing lost the connected segments comprising the circle and how to I reconnect them? I’ve tried selecting all segments and then creating a “Group” but that has not worked. I’m currently using SketchUp 2015.

So if you select the edge of the hole with the select tool, do you only get one edge segment highlighted? If that’s the case, there’s no circle anymore so there’s no center for Inferencing to find. Combining the edges into a group doesn’t make a circle.

The way SketchUp handles circles and circular arcs is a bit funky. There is no “circle” geometry object as such. Rather, there is a sequence of welded-together edges and some non-geometry metadata that remembers the center and radius. If you select one of the edges, SketchUp notices the metadata and knows to treat the arc/circle as a unit with the saved center and radius. But during some kinds of editing of the model, the arc ceases to be welded together and SketchUp drops the metadata. Thereafter, the inference engine can no longer find the center or radius and if you click on one of the edges you will get just that single edge, not the full arc or circle.

There are plugins that can weld the edges together again and that can (attempt to) place a construction point at the center, but redrawing is the only way to get a circle again.

It would seem that this a major flaw in SketchUp that Google needs to correct if they truly want SketchUp to be a professional tool like Aspire. Thanks to all the Posters for their replys :slightly_smiling:

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Just FYI, Google hasn’t owned SketchUp for more than three years! They sold it to Trimble.

Thanks for the Info; that’s a pity. I was always wondering what the references to “Trimble” were about. Then it’s all on Trimble to correct the flaws.

A pity? You must be joking. SketchUp would have languished with no development or perhaps been allowed to die as a number of other products did after Google decided they had no use for them. Since Trimble bought it there has been a great deal of development that never would have happened under Google.

I’m curious about how you could have SketchUp 2015 and not notice it didn’t come from Google.


I’m glad Google no longer owns it. I played with it for a couple days years ago. Back then i always felt there was the possibility that I put a lot of time into learning Sketchup only to have google drop it like some of there other product. This time around when I was looking for 3D software I was so happy to find out Sketchup was no longer owned by Google.

There’s a free plugin on Smustard called Midpoint. It places a guide point halfway between any other two points. Since an exploded circle is just a regular polygonal shape made of individual segments, you can use the plugin to drop a point between two opposing vertices of the polygon, a pretty accurate approximation of the center of the “circle.”


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Thanks for the suggestion Gully, but I think I’m going to switch to Aspire by Vectric. A friend and I are doing some CNC work; he already owns the pro-version and I can use the free version for edits. I think SketchUp has great potential, but when what should be simple edits require third-party plug-ins to correct, means to me that it’s not ready for prime-time.

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I’m really baffled by Google’s poor reputation hereabouts. I’ve always been a Google fan–so much so that I bought some of their stock in around 2004 when it was $186 per share and sold it for $486 a couple years later when I needed some cash to start work on my new property, nearly tripling my investment. During this same period, Google created the free version of SU and started giving it away just when I was getting serious about developing plans for my new house, something @Last probably would not have done.

I’ve got a Nexus 5 phone and a Nexus 7 tablet, both excellent, competitively priced devices loaded with free Google apps.

It seems to me that Google has, by and large, been pretty faithful to their motto, “Don’t be evil.” As for selling SU, that was simply an evolutionary development of their development strategy–just business. (The company I worked for was sold twice while I was there as our niche business (liquid fueled rocket engines) struggled to find a good corporate fit in a contracting business environment.) Why are they held in such low esteem?


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I don’t hate google and use many of there products too. Some of them I even pay for.

So you wish Google would have kept Sketchup?

I wasn’t slamming Google at all. They made it clear that SketchUp no longer served their needs when they started using other technologies to populate Google Earth with 3D buildings. They had no intention of investing money into continued development of SketchUp. Fortunately they sold it to Trimble who has invested a great deal in development. At least they didn’t do what they’ve done with some other applications and toss it into a closet somewhere.

I hold Google in high esteem. Business is business and they made a good business choice with SketchUp.

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I too like many things Google is doing, and, selling away SketchUp is perhaps one of them. As an AEC professional I hope that SU needs more and better features for the AEC community, and now it is in the hands of a company that belongs to that realm.


Finding the diametrically opposed vertices on a circle that has been turned into segments is a matter of eyeballing and hoping you get it right. The inability to identify such fundamental geometry as a circle is a bizarre failing for a 3d modeling software.

There is a “find Center” tool/plugin that I have as context click that finds centers of arcs and circles and places a useful construction point there, often this is handy when the inference method proves difficult.

Unlike a lot of other software, Sketchup’s MO seems to be to provide a simple but powerful 3D drawing base which has a lot of functionality but for which many of us have come to rely on plugins and extensions written by 3rd parties to to both streamline that functionality and provide additional tools to achieve results that would otherwise be very difficult if not impossible without. There has been some lively discussion on this forum as to the wisdom of this approach. There are some esoteric tools that very few people might use that might not be wanted in a default set of tools…so as not to “bloat” the software, but there are numerous 3rd party tools that are clearly improvements on some of Sketchup’s basic toolset (Fredo’s tools come to mind, if only the scaling functionality and the push/pull options !) which could easily be incorporated into the core tools of Sketchup. It may not be apparent to the buyer, having seen results from Sketchup, that you are investing in a foundation set of tools and then adding extensions for your own needs and thus creating a bespoke setup. Other drawing programs have the ability to add plugins (like photoshop, after effects etc.) but they have tended to incorporate what were once plugins into their core toolsets with each release. Sketchup doesn’t roll that way. The closest program that feels like/rivals sketchup with a toolset equivalent to a mass of 3rd party plugins is FormZ.
The only consolation to all this is that many of these plugins are free, but managing them is a chore when a new relaese comes out, but granted that this has been made more bearable with recent plugin management tools.

Emphasis added to the key point that Gully was describing - an exploded circle is no longer a circle. As long as a circle or arc is not exploded (even if it’s chopped into pieces where only a single segment remains) SketchUp can tell you where is the center. The “Find Center” function on the right-click (Context) menu (referenced by @whiterabbitdesigncompany above) is a native part of SketchUp.

There is also a plugin, Lines to Arcs that will reform an exploded circle and make SU recognise it as a circle and not just a welded curve.

When an arc is exploded there is the Chris Fulmer tool that will find an arc’s center based on two segments. This is a handy tool as I’ve otherwise had to manually draw perpendicular lines from the center of segments to find that point again. This would be preferable to do with guides and maybe there’s a key command to help, but whenever referencing from the centerpoint of a segment the tapemeasure tool will want to draw a parallel line and not a line to a construction point. It only seems to want to do that from an endpoint?

Whenever I’ve needed to find the center of an exploded arc (or similar situation), I do what you described: use the Protractor tool to draw two guide lines that are perpendicular to two chosen edges. The resulting guide lines are “first class” guide lines, same as those created by the Tape Measure tool.