Loop Cut Coordination technique

Question

A while ago I following a tutorial which demonstrates how to position loop cuts in specific places using loop cut, Grab X-Y-Z and giving a specific numeric so the lop cut can relocate to the desired position.

I'm trying to use the same technique on this mesh, I have added one loop cut on one of the triangular faces. Which I then used the factor to designate the position. But when I try to use the technique as the instructor, instead of the loop cut moving, the whole face moves and deforms. In this case, should I just use the factor after doing a loop cut on each individual face, or am I complicating things trying to do what the video instructor is doing?

Thank you.

https://www.youtube.com/watch?v=WSR6bVFe5LM

Answer 1

In the tutorial, the side 'rails' down which the edge is moving are parallel, so a translation (GY, for example) is equivalent to a slide (GG). On a triangle, that's not the case.

You can make a numerical entry for the distance of a translation, because all affected components move by the same amount. But you can't, by distance, for a slide, because vertices in a sliding loop will move different distances, depending on the location of adjacent vertices on the rails.

Instead, a numerical entry for a slide represents the fraction of the distance to adjacent vertices, where 0 is the current position, and distances to adjacent vertices are mapped to 1 and -1.

You might be able to use that fraction, with a bit of mental arithmetic, but usually, for accuracy, I find myself G translating single vertices down edges using Custom Orientations derived from them where necessary, and as far as possible thinking like a carpenter.. finding ways to transfer measurements from one part of a model to another.