For a good polishing of aluminium parts, you will need buffing wheels with different hardness.
I bought this form an classic car show. The are available for drilling machine, as well as for buffing motors.
This is my buffing motor.
It is a standard AC motor with 1500rpm.
Its better to get one with speed regualtion, but my one is working also.
Also you need buffing compound with different grains.
As starting basis i used a guiding tube.
At first i grind the aluminium until there are no scratch in the surface. I used a sandpaper with 180 grain.
And here the polished guiding tube.
For buffing i needed approximately 2 hours.
Advice:
The first step to polish the aluminium parts is, to grind the aluminium until there are no scratch in the surface. The left side is grinded, the right side is roughly polished.
This is the result after completely polishing.