I'm wondering if there's a snapping technique I could use to get a scaled edge ring to be exactly straight up and down? I can just scale and guess, by eye, that the edges that get scaled out are exactly upright, but I want to be exact, without having to set the location of each vertex manually. Thanks for any ideas.
While this is no general answer to how to solve the snapping problem and might not work for more complex shapes, in this particular instance I think it's easier to not rely on scaling but instead use Loop Cut and Slide, cut exactly at the bottom and then manually move the added edge loop upwards. For the upwards translation you could use exact numbers or vertex snapping (while restricting the movement to the Z axis) to end up at the height of your existing loop.
The slide method is given by binweg is better than scaling, because it's more general, but in this particular case, just out of interest:
- With the transform pivot set to the center in XY
- Set Snapping to 'Vertex' and 'Active',
- In Vertex Mode, select the edge loop to be scaled, making a convenient vertex active
- Scale in XY (SShiftZ) until the active vertex snaps to the one below it.