[pippin88]

Fix the area I've put a red line on. This bit was better in your original images.

Are you mounting rails directly to aluminium profiles?

Aluminium profiles are not precise or stiff.

They are good enough for a wood router. They are popular because they can easily be made as a kit for DIY assembly.

For a milling they are a poor choice.

[aphocks]

I appreciate you response, I recognize that 8030 is not ideal, but if you reference my original post I chose them because they give me needed flexibility. I intend to fill the frame with concrete so that the stiffness of the extrusions is not really important; as the concrete reinforced by the extrusions bears the cutting forces. I will look into improving the are you mentioned.