Thanks for the comment.

We create detailed drawings and determine the holes pre-fabrication. We are able to dimension the cross-braces individually and specify each hole location. Then it's in the hands of our skilled team on the shop floor. You can drill perpendicular to the surface and create a pocket, and then go in on the angle. Depending on your slope, you can also start in perpendicular and then slowly angle your bit out. Where you start your holes with either of these methods will depend on your layout (centerline vs edge, etc.).

Drilling these angles is not easy. Another reason this is one of our top-of-the line railing designs! Best of luck on your project.