Also be careful with edges (for example later Stronglight cranks) - they get rounded quickly! That is one of the advantages of sandpaper over buffing wheels - you can direct where you sand. (Most professional polishers use sandpaper if a part is very delicate.)
With the rougher grades of sandpaper, only do the flats, don't even get near the edges. Practice with a cheap bike boom crank or something to build experience and confidence.
The amount of material removed on flat sections is very little, as anybody who ever has tried to sand down an ITAL 22.2 mm stem to FR 22.0 mm diameter: Just taking off 0.1 mm takes a lot of time and effort. (In fact, it's more like 0.05 mm or less because the tolerances aren't that close and 22.1 probably fits fine in an FR steerer.)
Most parts aren't that far gone, and many were anodized anyhow. But when you are dealing with 50+ years of neglect on unprotected aluminum, it can look pretty sad! You get discoloration of the aluminum that goes pretty deep (by polishing standards, but rarely enough to cause structural concerns.)
Jan Heine, Seattle
>Don't forget to add a little dish soap when you wet sand boys.
>
>george argiris
>san diego, ca
>
>-----Original Message-----
>From: classicrendezvous-bounces@bikelist.org
>[mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of John
>Everett
>Sent: Tuesday, January 25, 2005 11:44 AM
>To: classicrendezvous@bikelist.org
>Subject: RE: [CR]CR: Polishing/Buffing Oxidation on Alloy Crank Arms
>(DavidAllen)
>
>
>On 24 Jan 2005 at 20:12, chris ioakimedes wrote:
>
>> Ouch!
>> Be careful with sand paper. I wouldn't use sandpaper unless I had to
>> remove deep scratches. Ouch!
>
>Agreed, I'd use only wet-or-dry paper, and sand wet. Once I get to
>1500 grit I go to the buffing wheel with jeweler's rouge. For that final
>
>touch I hand polish with Happich Simichrome (it's the best) and a
>soft cloth.
>
>Simichrome is sometimes hard to find. I bought my last tube in a
>motorcycle shop. :-)
>
>
>jeverett3@earthlink.net (John V. Everett)