Corner gets skewed by subdivision surface First of all I'd like to specify that I'm new to Blender and I can do only very basic stuff.
That said, I'm trying to model a sink and I need it to have corners with a given radius.
I started by creating only a quarter of the final model so that I can then use the mirror modifier.
I modeled the profile of the sink and then added some loop cuts to round up the mesh using the subdivision surface modifier.
I placed two loop cuts near the corner, placing them at a specific distance from the edge so that they have the same distance from that edge, thinking that in this way the subdivision surface will generate an arc with a radius of that specific distance.
This is what I have so far:

This is what I get after adding mirror and subdivision surface modifiers:

As you can see the corner loop cuts near the corner have moved and now the mesh is not forming a perfect arc on the corner but it is somewhat skewed. I think this is due to the subdivision surface changing those loop cuts' positions.
I tried toying around with the modifier's settings but nothing changed.
How can I achieve what I'm looking for?
This effect is a natural consequence of the Catmull-Clark algorithm, because the centers of adjacent faces,(and their sizes,) are used to calculate new edge-points.

If you're relying on Catmull-Clark to create your curve, and you want it to remain symmetrical about the corner, you will have not only to put in holding-loops for the corner itself, but at least one more loop to ensure the centers of the next faces along are also at an equal distance from the corner.