Selecting/Measuring the Center Point of a Circle/Arc

[Zero__]

Hey guys -

What is the best way to select the center point of a circle in Fusion? I have a sketch concerning a number of concentric circles/arcs and I'm worried that one of my construction circles used to locate a hole pattern may have become slightly "off-concentric" from a nearby arc. Though I could go to town with Concentric constraints, I need to know if this has happened.

What I would have done in NX is go to Measure, click and hold down on one circle and select the "Center Point" from the menu that would have shown up (similar to the "Depth" menu that shows when you click and hold on a feature in Fusion360. Useful for one multiple things overlap and you're trying to select just one). I would have repeated this with the other arc, and seen if the distance was 0.000 or if they'd come slightly misaligned. Barring that, I would have gone to Point, selected "center point". I would have clicked both arcs, creating a center point of both, then measured the distance between to two to make sure it was perfectly zero.

Neither of these methods seems to work in Fusion360. I haven't figured out how to make a Point at the center of an arc, and when I click and hold down on a circle or arc, selecting its center point isn't an option. So what's the best way to do this in F360?

Thanks!

[jeff_strater]

same basic method.

Invoke Measure, go over the points you are interested in, press and hold the left mouse button to get Select Other, choose one point, then do the same thing again.  You will notice that there are fewer items in the Select Other list because the first point is automatically prevented from selection.

Screencast:

Actually, you don't even really need to use Select Other, because of the selection filtering.  In the above case, you can just click and click again, and the second will be a different point than the first.  But, I like to use Select Other, so that I can see exactly what is going on - how many stacked geometries there might be at that location.

Jeff Strater (Fusion development)

[Zero__]

Hi Jeff - thanks for the screencast! As you can see from my sketch, I have a LOT of circles/circle arcs all at (supposedly) the same point. So what I have to be able to do is invoke measure, Select Other on the arc/circle, and have the central point of that arc as an option.

The problem with Select Other on the central point is I just get a looong list of "Sketch Point" but there's no indication of which arc they belong to. If there was some highlighting, this might work, but as you roll over the different sketch points their corresponding circles don't seem to light up.

A painful workaround I just figured out is to exit the sketch, go to Construct > Point at Center of Shere/Circle/Torus, create two Work Points based off the different arcs, and then measure the distance between those two work points. When I did that I found that my two arcs had indeed become nonconcentric by several microns. But having to exit the sketch to do this really slows down your workflow. If the Sketch>Point tool had options for you to select what type of Point you wanted to make (intersection point, bisecting point, arc/circle center point, etc) it would be much more useful.

[martinHTJH9]

I had the same problem coming from KeyCreator wich automatically highlights the center, midpoint or end of an entity. Why does F360 not make this type of thing easier to do - its should be logical! F360 team you must do a better job of this?

[TheCADWhisperer]

@martinHTJH9 

This is an ancient thread and all wrong today.

Can you File>Export your *.f3d file to your local drive and then Attach it here to a Reply?

I will demonstrate the correct technique to use in 2025.

[martinHTJH9]

Thanks I appreciat that but could not find anything better. Unfortunately the file I am working on is propriotary. But this is a general question. In most CAD software there are automatic was to snap to the end or center of an entity wheter it be a solid model or a sketch. I do find that the snap does seem to mostly work if you have a sketch but not if you are referencing solid part.

[TheCADWhisperer]

@martinHTJH9 

Simply create a dummy file that exhibits the behavior without revealing any of your proprietary information.

I have taught multiple CAD softwares over the last 30 years - they all use exactly the same logic, because geometry is geometry.