I've had my own polishing system for a fair number of years now and in fact just tossed out 3 burnt out motors which are essentially grinders with polishing components fitted. I've learnt that a polisher motor must have lots and lots of grunt. I have 2 motors set up with various pads from course wide discs to a calico flop. My favourite for alloy is sisal pads and I use different grit polish for different jobs. There are a couple of things I've learnt and that is different pads for different materials ie: chrome, stainless, alloy etc., and different grits for different results. I've never used a scourer pad not because I don't like them but because I know nothing about them. The pads I use are cotton, sisal, calico/linen. Various diameters are used depending on the job. For a tappet cover I would use a 1/2" wide x 2.5" diameter cotton or sisal disc to get into the tight spots. I would use a larger diameter pad on the flat areas. Narrow discs move more easily so a sprocket cover I would use a 1/2 to 1" x 6" diameter disc as this follows curves very nicely. The really tight spots have to be done by hand. A mission cover is relatively easy to do with a 1" or 2" sisal disc using a combination of medium and fine polish
Anyway, I telling this because I've done what Wayne has and that is I've stripped parts of the clear and what's generally underneath to my mind is a highly polished surface. These finishes vary because of the person polishing the part and the materials used to polish. Take the rear sprocket flange Wayne pictured You will notice that some areas are smooth and some are rough from the casting process. The smooth areas to my mind are as a result of polishing (that's an astounding deduction KP
) If I had an original casting I could render the rough finish to a smooth result in about a minute using a course high cut polish and sisal disc.Dead f'n easy
A major point to consider is that we have some parts which are cast from nearly pure aluminium whereas some are diecast and contain a lot of zinc and aluminium in combination. Some parts you can polish until the cows come home and they won't come up like original. A good example is the material used to make carb bodies. What you see is what came out of the mould. Same for the cases. The smooth finish on these parts is to my mind not polished. Some chain and mission covers are sandcast and polish up like chrome but the cast type tend to be a little duller unless a different polish is used.
Having done a fair bit of polishing I have found that leaving the finish in a raw state after polishing tends to bling the job up so if I'm not doing a clear coat I tend to employ med/fine grit on sisal discs and this gives that semi gloss finish. If bling is the order of the day then fine grit and red rouge on a large calico flop will make alloy look like chrome. If you use a clear coat on this gloss finish you then tend to get a factory type finish. Each coat takes a little of the dull off. I have also used an alloy cleaner on a highly polished part and that tends to dull off the finish surprisingly. My understanding is that Steven V gets excellent results using grit paper and others such as Mark employ plastic scourer discs and pads. I'm just not experienced with these materials so I've tended to stick with electric discs. The only negative is it's dirty work and the parts get very hot.
Anyway, there are probably others in the club who have more knowledge than I on this subject but I thought I would share some of what I've learnt. Essentially my take is to polish to a 90% gloss and then clear coat the job and I believe this is as close to original as I've seen.
Oh! Another thing is to work with the grain of the material. Fork legs spring to mind which seem to have a grain which I think may be from the factory finishing I canna be sure about any of that though. KP