Using array in a local coordinate system

So, I have a chair to array along a theatre floor.
I selected a face on the chair base and created a local UCS.
But when I make an array, the chair duplicates in the global coordinate system instead of using the orientation I wanted…
What am I missing? How to I use the local coordinate system I created?
Thanks

Custom Transform Orientations are not Local User Coordinates Spaces.
There is no User Coordinates Space in Blender.

They are just orientations that can be used by operators. Transform (rotate, move, scale) or Edit Mode operators (Extrude, Spin, etc…)
But that will not be used by modifiers.

Modifiers are just relative to object axis. If you want a modifier to use axis different than object’s local axis, you have to use another object as reference (generally an empty or a bone).
Here, you would have to enable Object Offset and precise name of object under the checkbox.

I’ll try that. Thanks

Still a bit mind puzzling but I think I got it! Thanks :smiley:

But now, I wanted to use the same empty to array the chairs in different rows. When I try to do that, the array gets messed up because it’s using the relative position of the empty towards the chair. It works for the fisrt row but not for the others.
Do I need a new empty for each row?

You just need a second array modifier with a second empty.

You need one modifier to define how many chairs per row and another one to define how many rows.
For each modifier, you need a proper empty unless you are satisfied by use of XYZ offset values.

Ok. that makes sense. thanks Zeauro.