Proportional Scaling


Im building a 3d printable beam structure based on tetrahedrons. I ran into quite some symmetry problems every time a part of the mesh is not parallel to one of the major XYZ axis.
Now I want to take the basic structure and make from it a superstructure one order of magnitude higher.

The problem I´m running into now is that I would like to keep the proportions on the whole part while scaling only one axis.

For example: I want to keep the proportions of the big triangle and scale it on the z axis to the height of my beam.
I was able to narrow it down to 9,008m (the beam itself is 9m) by scaling all axis until the z value is almost 9m, but I would like to be able to lock the proportion (or the two other axis) and the be able to scale without deforming the whole symmetry

As another example I snapped the top point of the beam to the superstructure and I would like to grab the lower part and snap it also to the corresponding part on the superstructure and still keep the proportions.

As stated this seems contradictory: to keep the proportions necessarily requires scaling by the same factor in all directions. Can you explain more clearly (or illustrate) what you really want to happen?

Best wishes,

Let me try with a Photoshop analogy.

Here I did the exact same movement for both version of the Bill Murray. I select the whole oriniginal Image and snap it to the top of the workspace. Then I grab the lower edge of the pic and move it up.
For the left version I just pushed it up the x-axis and pic got squeezed and lost its aspectratio/proportion.
For the right one I enabled the “lock aspect ration” button (round red cricle) and I could again grab only the lower edge and move it on the x-axis but this time the proportion is kept.

This I want to do with a mesh. I want to snap one part to a certain fixed position, lock two axis and proportionally move the other one.

Like in the first pic, I can scale the z-axis of the triangle and snap it to the exact height of my beam but then i loose the angles because the x and y axis do not move with it.

Or in the 2nd pic even if the beam were parallel to the z-axis, I would only be able to scale the height and the whole beam would be deformed flat. (Ideally here I could just grab the top and the lowest point and the whole mesh would follow not only the next vertext.)

Ok, this makes much more sense. You need first to rotate and then to scale your girder.
Put the 3D cursor at the end that you have already located correctly, and set the pivot point to be the cursor. Set the snapping tool to snap ‘Active’ instead of ‘Closest’, and make the vertex at the other end the active one (keeping the whole girder selected). 'R’otate, snapping to the target point on the superstructure, and then 'S’cale, snapping in the same way.

Edit: In general, you will need to rotate twice, about orthogonal axes, to get the alignment correct.

Best wishes,

Ok thanks. I managed the first part. My scaling operation has now the the pivotpoint as a source and Im scaling correctly in the right direction without the top part moving. But i cant get the lower point to be active and have the mesh selected at the same time. How do I do that?


Select the whole girder. Shift-select the end point, to deselect it. Shift-select it again, to reselect it and make it active.


Select the end point, making it active. Box select everything else, which doesn’t change the active point.

Best wishes,

Ahh perfect, now I got it thank a lot!