The pictures (particularly in iFixit's own tear-down) show a brushed finish, which would hide any machining marks. In any case, it's definitely a machined pattern, whether done directly on the finished part or along the way to make the die-cast mold.
It's crazy to think that they would apply a brushed finished to the inside of a machined part. Even crazier to think that they would incur the cost of a machined cover (expensive) instead of a die-cast part (cheap). Also, the item submitted for testing to the FCC has to be representative of the final product, especially in regards to anything that affects EMI/EMC performance.
I work in engineering for the #1 manufacturer/supplier of tactical radios in the US, and I'm telling you that is a die-cast part. The obvious reason for the stepping on the inside (vs a smooth contour, like on the outside surface) is to provide flat surfaces for the mounting of PWBs and other components inside the unit.
Of course, if you want to send me a sample to view up-close, we could put this to bed for good. :-/
I'm pretty sure Kenny Irwin died in July 2000 in a crash during Winston Cup practice at New Hampshire Motor Speedway.
It's crazy to think that they would apply a brushed finished to the inside of a machined part. Even crazier to think that they would incur the cost of a machined cover (expensive) instead of a die-cast part (cheap). Also, the item submitted for testing to the FCC has to be representative of the final product, especially in regards to anything that affects EMI/EMC performance.
I work in engineering for the #1 manufacturer/supplier of tactical radios in the US, and I'm telling you that is a die-cast part. The obvious reason for the stepping on the inside (vs a smooth contour, like on the outside surface) is to provide flat surfaces for the mounting of PWBs and other components inside the unit.
Of course, if you want to send me a sample to view up-close, we could put this to bed for good. :-/
The picture shows a die-cast rear cover. Just because it is stepped /= machined. There are no machining marks on the inside.