aluminium machining

[Jonathan]

I wasn't really sure the best way to machine this piece, I do actually have a lathe, but I wouldn't really know where to start with getting the piece center...

Presumably your lathe is big enough and you've got a 4-jaw chuck and dial indicator? If so then you can just do what m_c said, as that's how I'd do it (or I might line bore it). If you buy the bearings first then you can use them to help with the machining - when it's close take very small cuts and keep trying the bearing to see if it fits. If you set the compound slide to an acute angle you can use it to advance the tool in small increments more accuratel than using the cross slide.

Edit: This thread has more information: http://www.mycncuk.com/forums/steppe...-steppers.html