Split cube in half

Question

I'm new to blender. I wanted to split a cube in half.

I found these three steps:

1. Go in edit mode by pressing 'Tab'

2. Press 'B' for choosing the area that you want to be cut

3. Press X to delete vertices/edges etc.

When I press X the whole cube is deleted (even I selected only the vertices to be deleted). Why?

Answer 1

B - it is a select tool, not a cut tool.

If you want to cut something with line try to use bisect

Answer 2

I'll suggest Loop Cut .
(For if you want exact half, see point 5)

1. Go in edit mode.
2. do "ctrl+R", go over the mesh, move a bit to get the right cut (you'll see what I mean by that).
3. now press "left click" to select the cut.
4. you can move the cut (by moving the mouse) to desired position.
5. press:
   "right click", for exact middle cut.
   or
   "left click", for the selected cut.
   
6. now select one side of the vertices and delete those.

Answer 3

Another (more precise imho) is using the knife tool, with "midpoint snap" option and "cut through" mode activated. Follow me:

here is your cube

now move to front (or side) view

now activate the knife K, and activate the "cut through" mode pressing Z, and remember to set the "midpoint snap" (keeping CTRL pressed) just before clicking left to start the cut.

keep an ey eon the "status bar", as highlighted below, to be sure of your knife operation mode:

if you are keeping CTRL pressed, the "start cut" green square preview will stick to the midpoint of that edge.

now drag to the bottom edge always keeping CTRL pressed, to set the "end cut" preview point. If unsure or made wrong steps, press esc to retry from the start. When perfect, press enter, and the cut will be made.

If you remembered to activate also "cut through" mode pressing Z at the beginning, you have this:

and selecting one side of vertices

you get a perfect (and easy) half cube shape

it's simpler than it seems, looking at it in action: