Hi Bravlin, it sounds like you're looking for an object snap that would automatically project the y axis onto the sphere. Unfortunately there isn't any built in snap that does that, the only snap that goes on the interior of a surface is either the "on surface" snap from a view direction rayfire, or the "cen" snap on a planar face bounded by line edges like the face of a box. The reason for that is because of performance - there is a lot more computation involved on projection and intersection calculations on surfaces instead of curves. It wouldn't really be a problem on your sphere case but it's also possible to have stuff like a surface with 5,000 x 5,000 control points in it and it would not be good to try and calculate a projection or intersection on a surface like that right in the middle of drawing.

Usually surfaces have a lot more edges to work with and you can target snaps on the edges to get what you need. The sphere happens to be the most sparse type of surface when it comes to edges since it has only a single edge on it.

But you could still make use of that edge if you rotate your sphere into a good position for your pick. You can use the Transform > Rotate command for that or a quick shortcut is to use the "wheel mode" of the edit frame. That's when you click and release on the rotation grip instead of dragging on it. That turns on the rotation wheels and in your case 2 drags would get it to the right position. That looks like this:




So other methods would be that when there is not a built in snap that will automatically give you what you need, you can build some helper curves or points which will have the needed snaps. There are numerous ways you could do this, like draw a line along the y axis and cut the sphere into 2 halves using boolean difference, or draw a y axis line and use Construct > Curve > Project to project it onto the sphere making a great circle on the sphere that you can then snap on to, or draw a line along the z axis that pierces the sphere at your desired spot and use Construct > Curve > Isect to intersect it with the sphere to get a point object to target.

A lot of times some strategic use of construction lines can also get you the needed snap point. In your case here it's possible by making a construction line from the center of the sphere to the end of its edge and reorienting the construction line endpoint to point in your desired direction. The thing that's nice about construction lines is that you can use them when you're in the middle of the orient command and they go away when you're done so you don't need to run any other commands or do any clean up steps. That looks like this:



Let me know if you need more detailed information about any of these methods.

- Michael