Tools On Surface (extension) Arc tool


So I installed “Tools On Surface” extension to draw on a curved object.

The Arc tool in the extension produces odd results:

image 1

image 2

I tried making an Arc the same way as a 3-point arc: (I click 2 end points, then try to add curvature to it. Instead of a clean arc, it moves the end point and creates and oddly shaped curve.

What am I doing wrong? Can’t find a solution in any tutorial I found.

Thank for you in advance…

How about sharing your .skp file?


Hello mihai.s

Wow, you literally rebuilt the pyramid shape that took me 20 mins to make. Thank you!!!

When I draw the arc, I get the same result as you on the 1st try. I don’t understand what you do differently on the 2nd (successful) try. Do I need to hold down a key?

with SketchUp Make 2017

No. Just try to see if it’s work for you.

Thanks. It didn’t work with the Arc. On your animation, I can not see what you do differently between the 1st time and the 2nd time you do the arc.

I’m just drawing the arc, like the first time.


or use the basic tools from SketchUp (line, arc, pushpull, intersect faces, erase)

Thanks mate. Drawing the arc fails every time I try it, I keeps showing me this:


I will check you other method tomorrow morning :slight_smile:

Only difference I see is the camera angle. Sometimes it helps to orbit to a different view to make the tool do what you want.
Rectangle tool if you want it upright for instance, or dimensions…
See if it helps…

I see, I tried countless times and the Tools On Surface Arc tool did not work as expected. For no reason the end point moves away from where it originally was.

The second method (intersect faces) worked, but it is a lot more work than simply drawing an arc on a surface. It is unfortunate that the tool did not work as intended.

Thank you all for your kind help!

The name of the tool gives you a big clue to how you need to use it.
On Surface.
It will follow any surface you move the cursor over, so you need to keep your cursor on the surface you want it to create the arc on.
See in the gif how as soon as I cross the line of the corner it changes shape, but move back onto the surface and it does as needed.
On surface

Hello Box,

Thanks a lot for your help. I have been trying the exact same thing, but with no luck. I wan’t able to get a clean arc even one single time. See video:

Attach your model.

arc on curve error.skp (317.7 KB)
Ok, attached.

There are limitations in all tools.
You’d probably find it easier to get the shape you want by intersecting a curved face.
For example.
GIF 24-03-2022 9-06-01 PM


different ways on different faces


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Got it, thank you all for your helpful input.

The arc on curve tool is finnicky, but I guess it is not ideal for creating an arc which is near tangent to an edge.