# how to change a dimension on one side (of that dimension) only

How can I change one dimension of say a cube so that the change (say the width) is made to one side (of the width) instead of (half the change) on each side. Hope I make sense. Here is an image of a dock I want to create. I created a 'bent' rectangle as the bridge deck, copied it and placed it above the deck which I want to use as the handrails keeping one side perpendicular to the edge of the deck. I will then add the girders between the deck and handrails. Just want to make it easy to have the handrails perpendicular to the sides. Imagery will never be viewed closer than 10 metres away so accuracy in detail not required. The image also contains in image of the actual bridge.

• The change is done proportionally from the object's origin. It's the only fixed point when you change the scale of an object (in object mode at least) You can think of it like a balloon, when you blow air into it, it expands proportionally in all directions, because its origin point is at the barycenter of its geometry. But if you somehow glue one part of the balloon to a wall, and try to blow air into it, it will expand outwards from the fixed part. Or you can change the dimensions in edit mode like suggested in the answer which is easier and less error prone Commented Jul 16, 2021 at 7:24
• i updated my answer Commented Jul 17, 2021 at 5:14

1st method

Select your cube, press TAB to enter edit mode, select "Face select", select the face and move it with G (or G G)

2nd method

Select your cube, go with TAB in edit mode, select all with "A" and move the mesh to the right with "G" -> "X" so that the origin changes to the left face.

If you then scale e.g. the cube with S -> X only one side will be affected.

3rd method

Just for the crazy ones.

Face select the right side of your cube in edit mode. Shift-S -> Cursor to selected -> Add empty

Be aware: i made this for the default cube, you might have to adapt it for other dimensions.

Add driver for x location of cube like this:

add driver of scale x of cube like this:

BEST METHOD (just the private opinion of me)

Use geometry nodes like this:

UPDATE:

2nd method explained on this object:

Go in edit mode, select the left edge and press Shift-S -> Cursor to selection. Then back to object mode: object -> set origin -> to 3D Cursor. If you then scale, it is hopefully what you want. Try scaling S->X or S->Y or S->Z.

• Thanks for the fast reply however how do change one of those dimensions TO a particular value. If the start cube is 2m x 2m x 2m and I want to end up with 2m x 2m x 0.2m EXACTLY how do I do that. The dimensions displayed top left don't seem to indicate what the end size is. Commented Jul 16, 2021 at 7:41
• use method 2. Then type S-> X -> .1 or enter .2 in dimensions [1]: i.sstatic.net/yNJJb.png Commented Jul 16, 2021 at 7:50
• Thanks. Something else I have now learned. Commented Jul 16, 2021 at 8:20
• you are welcome. That's good!!! ;) i am still learning every day ;) Commented Jul 16, 2021 at 8:23
• Well I can't work out out to apply any of these methods for my model. Firstly the scenario. I am wanted to create a small bridge which will eventually have girders on the sides between the bridge and the hand rails. I created a simple rectangle (Y 10 X 2 Z 0.2) and 'bent it' in the middle so that the middle of the bridge is slightly higher than the ends. I then duplicated the original bent rectangle and moved the duplicate above which I want to reduce in width to form one of the handrails which will be perpendicular to the side of the bridge which I will then duplicate for the other side. Commented Jul 17, 2021 at 4:35