How to scale dimensions of a model while keeping the other dimensions proportional ?? I want to make my model "4cm" in order to be able to 3D print the model. I've applied the scale of my model, and I am trying to change the dimensions of the Y-AXIS from 11.817 m to 4cm, while the other X and Z axis scale proportionally. 
But, I the X and Z dimensions don't scale to their proportional sizes to the Y-Axis of 4cm, and turn into X:0 and Z:0 .
Is there anything im doing wrong? or another way?
Here are the steps you could follow:


Select your model in Object mode, Hit CtrlA
Hit S and start scaling.
Scale close to the value you want, and then hold the Shift to fine tune the scaling as you move your mouse.
LMB to complete the scaling operation.