Ouch! Be careful with sand paper. I wouldn't use sandpaper unless I had to remove deep scratches. Ouch! 4/4
Chris Ioakimedes http://www.fattiretrading.com
-----Original Message----- From: classicrendezvous-bounces@bikelist.org [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of Jan Heine Sent: Monday, January 24, 2005 8:06 PM To: classicrendezvous@bikelist.org Subject: Re: [CR]CR: Polishing/Buffing Oxidation on Alloy Crank Arms (David Allen)
Polishing aluminum isn't hard, it's just hard work. Don't ask me about the hours spent on my Herse tandem that had spent at least 15 years in an aviary! Especially high-strength alloys (such as 7000 series) oxidize readily and relatively deeply.
Here is how:
Sandpaper first. Start with 400, if that doesn't yield results, go coarser, all the way to 180 grit. Once all the oxidation is gone, you'll need to get it smooth again (remove the scratches from the sandpaper).
To do so, move in small steps toward finer grits, all the way to about 1500 or even 2000 (the finer ones are available in auto parts stores for rubbing down paint). Sand in one orientation with one grit, then 90 degrees to that with the next finer grit. This allows you to see whether you have removed all the previous scratches. (If you don't get them all, you have to start over, as there is no way you'll remove "320 grit" scratches with 1000 grit sandpaper.)
Once you are done with the sandpaper, it should look close to polished, but holding it against the light, you see the scratches. Then polish with whatever. 3M makes a product for cleaning aluminum boats that removes a lot of material, but you need to follow up with a finer compound.
Don't worry about strength, you'll take off not even 1/10 mm of material unless it's a lost cause.
If your cranks were anodized, the anodizing will be gone once you are
done. So I do this only with non-anodized parts.
--
Jan Heine, Seattle
Editor/Publisher
Vintage Bicycle Quarterly
c/o Il Vecchio Bicycles
140 Lakeside Ave, Ste. C
Seattle WA 98122
http://www.mindspring.com/
Listers and Listees,
Help ya'll!!! I know I'm going to get spanked down on this so let it rip......
I've got an alloy crank (Shimano 600 - relax, it's an 1981) that has oxidation staining on it (probably from putting it in my dishwasher...duh). What is the best way to get rid of this oxidation staining and get this crank all shiny and bright? Buffing with a jewelers compound??? The stains look sort of like water marks. I hope these aren't from the dishwashing detergent. Let me know please.
David Allen Marietta, Georgia near the Big Chicken
P.S. Japanese Bikes? Why not Super Mizutani ????? With the Akita on
the
brass headbadge!