cut edge precisely?

[raincole]

As far as I know there are two tools I can use to cut an edge: knife and subdivide.

But knife can only cut at midpoint(0.5) or a free point(not precise). And subdivide can only divide edge into some equal parts.

How can I cut at a certain point? For example, I wanna divide an edge into two edges whose ratio is 3:7.

[Fred2_]

You could also create an edge and use the tiny cad tools to create verts where 2 edges intersect. You might have to fill in some faces, delete a few extra verts and edges, but is precise, especially useful if a new transform axis is created for that edge

[ridix]

You can key in exact coordinate for the cut point; easiest if and edge is on axis.

[encn]

On the spot I'd use one of the following wonky workarounds.
A) might be impossible depending on the geometry B) really isn't as messy as it sounds, C) I'd seldom use.

A)
Edge Slide allows numerical input, and plays well with n-gons and weird non-manifolds. But you'll have to work the math out from the midpoint.

B)
1. subdivide the edge once
2. activate Active Element as Pivot Mode
3. Select the new vert, then one of the edge end-points
4. "slide" the vert numerically precise by hitting S, then the number.

I might snap the new vert into one of the endpoints and scale it towards the other, if the more straightforward 0-1 scaling math is worth it.
Also, only selecting new vertices between operations, the value-scaling is repeatable with shift+r.

C)
1. Subdivide the edge into 10 segments
2. Dissolve the verts I don't want.

[ajm]

If loop cut is an option, activate that and enter .428 as the edge slide value.

[jray]

On the spot I'd use one of the following wonky workarounds.
A) might be impossible depending on the geometry B) really isn't as messy as it sounds, C) I'd seldom use.

A)
Edge Slide allows numerical input, and plays well with n-gons and weird non-manifolds. But you'll have to work the math out from the midpoint.

B)
1. subdivide the edge once
2. activate Active Element as Pivot Mode
3. Select the new vert, then one of the edge end-points
4. "slide" the vert numerically precise by hitting S, then the number.

I might snap the new vert into one of the endpoints and scale it towards the other, if the more straightforward 0-1 scaling math is worth it.
Also, only selecting new vertices between operations, the value-scaling is repeatable with shift+r.

C)
1. Subdivide the edge into 10 segments
2. Dissolve the verts I don't want.

Thanks Cecn

[raincole]

Thank you @encn. B) is so clever. I'm wondering why I haven't thought of it.