Oh the hells of buffing, where to start?
First thing is I would most certainly get a designated buffer motor with long shafts and the right wheels. Buffing on the lathe is a pita and I find it takes 10x longer than using a buffer with the right compounds.
I polish parts a lot and what it comes down to is simple.
Initial surface finish. If you start with a grooved piece of aluminum and try to buff the groves out to a mirror with just the finish rouge you will be there all day. I am always trying to get things done as economically as possible and have found that a DA or orbital sander first works best. anything off the lathe I will hit with 320+ as it shouldn't need more than that. I then switch to a hard bar for aluminum (its red) or stainless (its grey) on a stiff but soft wheel. Once finished buffing the entire surface I move to the other side of the buffing motor which is set up with a large dia. soft wheel with much less plys (sewn rings which add the stiffness to the wheel) Here I use one rouge only, a hard white bar for finishing.
What it comes down to is pressure, process and the correct equipment i.e. wheels and rouges.
Before I discovered the secret of the DA I would use soft bars of different grit and slowly work up 80, 120, 220, hard bar, finish bar. Now I save a ton of time DAing 120,220,320, hard bar, finish bar. It goes so much faster and there is a lot less cleaning wheels and applying new rouge.
This is getting lengthy but there is a good bit of info learned through experience. I find if I'm not getting good results which just means black gunk is building up on the part the wheel is out of rouge, add more. If your bad results means its not polishing up to a mirror you need to go back get some 220, sand it and keep sanding until all deep scratches are removed. Sometimes its hard to tell if they are all out on a dull piece of aluminum but you will know as soon as you try to polish and the scratches appear.
As far as rpm goes 1750 is fine. Buffing motors are $ but you could get lucky, search CL thats where I found my Baldor...$25 I used the rest of the money I had planned on spending to buy wheels and rouge.
Baldor Buffers, Merit Abrasives, Specialty Buffs, Seymour Paints, Sand and Bead Blasters, Metal Working tools and more - Tarheelparts
This guy is very knowledgeable and will take time to answer any more questions you have.
Finally, last nights work. It still looks like I'm wearing eye liner, did I mention buffing makes a HELL of a MESS, wear a respirator!