I realize this was not the question, but many CR-correct aluminum parts were not originally mirror polished, so "restoring" them in this way is not an act of restoration but of artistic license. Examples: the Campy Nuovo Record parts. Some,like the seatposts, were sand-cast and have retained the sand-cast texture. The clamp area of the seatpost retains its sand-cast texture. The shafts are very finely finished, but it was a very high-quality machined finish, probably lathe-turned. Not mirror polished.
Similarly brake calipers and crank arms/spiders had a matt finish that is similar to an anodized surface, but were not anodized. I don't know how the finish was achieved: simply a fine casting finish, or a tooled operation that did not leave tool marks, or perhaps a bead-blast of some sort. There was some luster, but not a mirror finish. It's not right to mirror polish them.
It is (imo) right to perform certain filing operations that should reduce cracking and crankset failure. Had I known of this problem back in the day I'd have radiused the sensitive areas, so I feel it is plausibly correct to do so now, to enhance the durability of my bike.
On Fri, Nov 13, 2009 at 11:34 AM, Kurt Sperry <email@example.com> wrote:
> Polishing unanodized aluminum to a mirror finish doesn't require a lot
> of sanding steps. You can quickly sand out any pitting or scratches
> with 220 grit dry then go straight to the buffing wheel. Start with
> bobbing compound on a cotton wheel and follow that with Fabuluster.
> Use two different wheels, the polishing compounds are available
> through any large jewelry supply house. You can get a less bright but
> shinier than satin finish by stopping after the bobbing step. I
> always cringe when I read people describing how they went through
> multiple hand sanding steps over hours to get what is probably not as
> good a polish as I can get in a few minutes. Careful with the buffing
> wheel though, it's dangerous.
> Kurt Sperry
> ms , hubs etc. For the most part I leave anodized parts alone. For non
> anodized parts I wet sand with grits up to 2500 and buff with Tripoli
> compound and white rouge. What I'm wondering is there any equivalency scale
> to correlate the various abrasive media. Is Tripoli finer than 2500 grit
> paper, where do the steel wool grades "0", "00" etc fit in.
> > It would be helpful to know the equivalency in order to know when to
> stop the tedious sanding and move on to the easier to apply buffing
> compounds. Does such a correlation scale exist? For those of you who also
> polish parts what have you learned? What do you use for a mirror finish? For
> a satin finish? Opinions welcome.
> > Norm Lafleur
> > Ashfield, Massachusetts
> > USA
> > _______________________________________________
Ann Arbor, MI USA