buffing campy crank arms
 

i,ve been shopping around for a campy crankset and have noticed a majority of them have the original finsish rubbed off in places and are scratched up. has anyone tried to buff these out, if so what kind of result did you get. thanks

A friend did a pair years ago on my buffing wheel. You can make them look like chrome. First you need to remove the anodizing. Naval Jelly (rust remover) will do it, but you need to be careful, it will eat into the aluminum too if left too long. We used to put the part into a plastic food bag with a Zip Lock, add enough Naval Jelly to cover then massage it around every 10 minutes for a few hours.

Honestly, after my friend finished he said he'd never do that again. Took a couple days to clean and polish everything. I have a set of 151s in rough shape I'll probably go that route on.

Buffing out a crank does take a lot of elbow grease and time as there are so many nooks and crannies you hae to hit. You can do a mirror, chrome-like finish on them , but I think a satiny finish with directional grain looks so much better. Trick is to get it as polished as close to mirror finish as you can, then you hit it carefully with gentle directional swipes with fine Scothbrite pads. If you will look at NOS cranks, this finish will match it very closely and sometimes even look better as you are in control of how you apply the "grain".
BTW, If you do buff a crank out, Make sure you do not create any stress risers by grinding and polishing the material down too much and creating very thin edged corners anywhere on the crank where stress cracks can start propagating. Buffing/polishing the crank will also give you the ooportunity to knock down stress risers edges and corners that the factory originally left on the crank.

Chombi

Interesting Chombi. Any other stress danger areas other than the usual web where the arms meet the spider?

I'm often tempted to do a little filing to smooth things out when cleaning up an old part. Wish I could get "How Not to Create Stress Risers 101" with examples.

assuming anodized surface is all gone anyhow,

would simple steps of:
1. steel wool + scotchbrite rub
2. hand held rotary tool + polishing felt tip + a bit of polishing compound
work? or is it just dangerous for this particular part "crank arm"?

thanks for the replies, i have a buffer and have buffed a lot of things, but i didnt know about the naval jelly dissolving the original finish. thanks again.

Along that line. If you are going to buff, you might as well do some shaping before hand to provide stress relief at the crank arm/spider area where the Record cranks tend to fail. I used to have before and after pics but cannot find them.

It's interesting that the OP did mention Campagnolo cranks for possible buffing out, as Super Record cranks are notorious for cracking at the spider and arm junctures. Some early Mavic cranksets (the fluted non-starfish ones) supposedly had similar problems. Most attribute it to sharp corners at the crank and spider arms juncture that could have been rounded or "eased out" during manufacturing to avoid any stress riser situations.
Other than that, the only areas I've heard of cracking on some cranks is right at the middle of the main arms when a nick or gouge on the surface supposedly propagated right through and across the arm, causing them to break suddenly as most owners never see the crack or most of it was developing under the surface of the crank arm. Some also suspect that these mgiht have been also caused by bad casting/forging at the factory but both theories have not been disproven so far.

Chombi

Use this to remove the anodizing:

http://www.jestcoproducts.com/index....d&productId=37

Any other methods are not going to work anywhere near as well, and will waste tons of time and effort.

Prepping for polish should eliminate stress risers not create them. You want to concentrate on the two little valleys where the inner most spiders join to the arm. That's where they always crack. You want to file the sharp web out and roll that edge over nicely without under-cutting into the arm.

Then dress all the edges front and back of the spiders and smooth the edges between the spinders:

http://farm7.staticflickr.com/6077/6...d278e076_b.jpg

A word of caution. The driveside Record crank is one of those parts you REALLY have to pay attention to when using a buffing wheel. There are many hard to get spots, and spots that put the edges of the spiders in a very dangerous position to get grabbed. Be careful.

1st gen C Record i polished up, they had typical shoe and toe strap wear with scraps on the arm ends....

http://i495.photobucket.com/albums/r...3/DSC01588.jpg
http://i495.photobucket.com/albums/r...3/DSC01596.jpg
http://i495.photobucket.com/albums/r...3/DSC01589.jpg
http://i495.photobucket.com/albums/r...3/DSC01591.jpg

Nice C Record crank there. Definitely a jewel-like result! I have an identical looking crank, that needs a polish job too, but I'm wondering about the Campagnolo logo on it. IIRC, the one I have has the same looking but what looks like silkscreened logos. so they might go away if I do the polish job. Is it even a C record then?

Chombi

not sure if C Record came with screened logo, but in my knowledge the signifier of C Record was whether the arm itself is one of the spiders or not—meaning one leg of the spiders is actually hidden behind the arm. in Chorus, Croce d'Aune or Athena group, the arm is pulled from inbetween 2 spiders, making slightly more complicated shape than C Record. no?

Yup, the arm on my crank coubles as a spider arm. One of the ring mounts is behind the arm.......it also has the same self extractor(?) spindle mounting bolt as shown on the pics from miamijim.

Chombi

I just finished a pair of those C-Record cranks today for a customer. The anodizing was like paint, and revealed lots of pitting once removed. These were not well finished before being anodized like the earlier Record cranks. I was able to get most of the pits out but had to leave some on the back. It was twice as much sanding as I do on a Record.

http://farm8.staticflickr.com/7013/6...297b981e_b.jpg

Damn Otis, that is gorgeous! The milling looks incredible on that, I never would have thought to do that to a C-Record.