Is there a way to manipulate the co-ordinate system in sketchup? I want to place the co-ordinates on an arc tangent and draw in the x - z plane.

I’m not sure I understand ‘I want to place the co-ordinates on an arc tangent and draw in the x - z plane.’

Do you mean you want to rotate the axes so one of them is tangent to an arc at some point on it?

You can reposition the axes wherever you want, but internally, SU will still record things in the original ‘World’ coordinate system. However, it will make the transformations to things you subsequently draw so they stay in the same position wherever you subsequently put the axes.

To do what I think you meant, R-click on any of the visible axes, choose Move, and reposition and align them where you want on the arc. If you want to make the x-z plane in your new location different from the ‘world’ x-z plane, you can. but you may find it very confusing.

‘Tangent’ will here be taken as ‘along a segment of the arc, at either the midpoint or endpoint of a segment’

Thanks, John. That is what i want to do. I appreciate your reply.

Thank you, Dan. That helps. - steve