Finding the center of a circle when it has been exploded then regrouped

This problem is not really like
“How to find the center of the circle.”
When a shape is drawn, it keeps all the features to connect to handles and when you hover, many handles appear. That I know.

I went to 3D WareHouse and found pipes.
Once I move to copy them and they are out of their frame,
when I double click on it, every items that constitute the shape are separated.

Some side of the circle (cylinders) are larger than others so it is pretty hard to select an endpoint that is exactly at 180 degrees on the other side of the circle.
When I select the whole shape (which is a group) I can see the cubic form around the shape but it is a group, so I cannot select something that I can trust as to be exactly at the center of the circle.

I will try to leave you a picture.
Because, even if I deleted all other 20 pipes size, the file keeps saving at 38Mb.
Even for a single 6inch pipe.

So I need you guys to find a way because it is not the first time that I have that problem.

Assuming their are vertices across the center from each other you could put in a couple of guidelines between them that intersect at the center. There is a plugin available from Sketchucation called Exploded Arc Lines to Arc that will convert an exploded circle back to a circle. There are some other plugins that will find the centers of exploded acrs, too.

How about sharing the .skp file. I tried searching on the name you gave but didn’t find it.


I’ve tried to attach it to the post and I kept getting error messages.

The file is 36 054 Kb and even in Outlook, it tells me that the file is too big to send.

If you l;ook for : 1 inch Steel Sch 40 Nipple NPT Fittings

In 3D Warehouse, and click Models, you’ll see it

I used the plugin I linked to to convert the inner edge back to a circle. Then found the center.

Here I selected two neighboring edge segments and used Arc Centerpoint Finder by Chris Fullmer which is available in the Extension Warehouse. It doesn’t recrate the circle but it does find the center.

How are you using these pipe components? Seems like they are kind of heavy to use in a plumbing model.

I really like the idea Mihai, Thanks

Nice, Thanks.

I’m on it.

You’re welcome!


I downloaded it.

Thanks Eric.

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This suggests to me that there are component definitions in the model for which there are no instances arranged in the model’s 3D space. When you import or download a component into the model, this actually adds two things: the component definition, and an instance (a “living, breathing copy”) of the component. Deleting the instance (the visible copy in the 3D model space) does not delete the definition - it remains in the file (and consumes most of the space related to the component). There is a Purge Unused function on the Components window which will cause SketchUp to remove all component definitions for which there are no actual instances in the model.

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Pipe Nipple.skp (556.6 KB)

Reduced to a single component as per @TDahl.

It’s still kind of bloated for a larger project and it’s not especially clean. Missing faces and other issues.

Another tool that would reconvert exploded circles back to circles is Eneroth Autoweld. It’ll weld any edges that can’t be welded.

I love the plug ins but a very simple way to find the centre is to use chords, Any chord, a straight line through the circumference of the circle with a line drawn at 90° from the its’ centre will pass through the circle’s centre. Select at least 2 chords and draw the lines at 90° from their centre point and the intersection will give the circle centre, alternatively if the circle is still complete, right click on it and select ‘find centre’ sorry “center” - I’m British.

As shown in two replies above by @mihai.s . :slight_smile:

Missed that! No words with the GIF and didn’t watch it.

The very nature of sketchup geometry and the inference engine helps you with this.
Assuming the original circle has been drawn with an equal number of segments you can just draw an edge between any two opposite vertices. Here I have deliberately drawn the circle off axis and exploded the curve.
So join the dots and use the midpoint of the edge.
Circle centre

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Draw perpendicular lines from the midpoint of two edges of the arc or circle. Their intersection is the center point of the arc or circle. Very quick to do and no plugin needed.

This true if the circle is made with an even number of segments. With an odd number of segments, it won’t work.

Which is why the sentence you quote starts with…

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