>Steel is relatively easy to machine Aluminum can be even easier. Mechanical engineer here. This depends heavily on the alloy you're dealing with. Many Alumi

>Steel is relatively easy to machine Aluminum can be even easier. Mechanical engineer here. This depends heavily on the alloy you're dealing with. Many Aluminum alloys are so soft that they'll actually melt and subsequently bond to the tool surface when they're being cut/ground/sanded/etc. Also Aluminum tends to have a very low shear strength which means it won't hold a thread the way most steels will - this is why you typically see rivets in aircraft skin.