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How to polish a crank?(10 posts)

How to polish a crank?Brad S
Jan 24, 2003 11:13 AM
I am hoping I can get some good advice here.

I have an old pair of Dura-Ace 9 speed cranks that I have scuffed up pretty bad from my shoe rubbing them. The Dura-Ace logo is completely worn off (long time ago), and I have actually polished a small area were the logo was from my foot rubbing it. But it looks like crap around that area, kind of like some type of varnish, and of course there are a few minor scratches on the cranks. So I would like to polish the whole crank to a mirror like polish that resembles the rubbed area.

I have tried using some White Lightning Metal Brite, which is supposed to "Restore, Polish, Protect", but it really doesn't seem to make a difference no matter how long or how hard I rub it in.

Now I don't have any access to power tools, so I am going to have to do this by hand. But what type of polish cream or cloth/sand paper can I buy to polish these cranks to a mirror like finish?

thanks in advance for you suggestions.
re: How to polish a crank?scary slow
Jan 24, 2003 11:24 AM
try using Mothers Mag Wheel Polich. You can find it in the automotive section at Wal Mart or most automotive stores. I used it for an old set of cranks that I have...they truly look new again.
Ever-finer sandpaper followed by Simichrome?retro
Jan 24, 2003 11:25 AM
Personally, I wouldn't polish it--use the time riding the bike. If I wanted to polish it, though, I'd start with a fine wet-or-dry sandpaper (200 grit? Depends on the depth of the scratches), then work down through 400 and 600 until I had it as smooth as I wanted it. Then a good metal polish (Simichrome is one) should bring it to a mirror finish.
Any hardware store or fuzzy-dice car parts place should have the stuff you need.
skip the 200 gritTig
Jan 24, 2003 5:18 PM
I'd almost say to also skip the 400, but it might be fine to start from there. Follow up with the 600 and finish with emery cloth of ultra fine steel wool. Keep the sanding strokes long, even and all in the same direction.

As a finish carpenter and staining/varnishing pro at a door shop during my school days, I'd sometimes restore brass handles on doors. I'd start with 400, then 600, then fine steel wool. A clear coat kept them protected for about 1 year.
You sure you want to do this?AaronL
Jan 24, 2003 11:28 AM
Cranks are anodized and once you take it off, you'll forever be cleaning/polishing them.

What you've done is you've worn through the ano'and exposed the bare metal.

But, if you REALLY want to take it off, Easy Off oven cleaner will take of the ano pretty well.

If you are going to hand rub the cranks, use simichrome or jeweler's rouge. It's going to take you quite a bit of time, so be very patient.

One thing you may look into, and I've always wondered if it will work, is kits sold to the folks that polish the aluminum components on motorcycles, like the swingarms. There are DUI kits that allow you to coat the parts after they are rubbed out. Maybe someone else out here has experience with it.

I've polished several cranks in the past and although they look good initially, the upkeep is a royal pain.
Jan 24, 2003 11:32 AM
Wanted to say DIY, not DUI.

Whole different ball of wax!
OOPS!Woof the dog
Jan 24, 2003 6:19 PM

Funny guy!

woof the god
Aaron has a valid pointRickC5
Jan 24, 2003 1:04 PM
Anodizing is NOT a surface treatment like paint. Anodizing becomes part of the aluminum, and can ONLY be removed by a chemical process, OR by using a VERY high torque, high speed buffing wheel (like 12" in diameter). Removing the anodizing by hand will become a lifetime endeavor if you are determined to do it by hand.

My recommendation is to take the crank arms to a metal finishing shop and let them decide how best to remove the old anodizing and then have the arms re-anodized. I'll bet they will want to bead-blast, which is fine, but when they're done, the arms will have rather a dull look (but you could have them done in a cool color). Very durable, but maybe not what you want. I would estimate that bead-blasting and re-anodizing shouldn't cost more than $30-40.
very fine steel wool might work_rt_
Jan 24, 2003 12:10 PM
you can buy it at someplace like Home Depot or Lowes. i used it during a bike restoration project on the cranks and took them from this:

to this:

on the other hand, even very fine steelwool might scratch the cr@p out of DA cranks, so i'd suggest trying it out on a spot noone can see first.

DA ranks are clear coated not anodizedCarbonfiberone
Jan 24, 2003 3:03 PM
If there are no deep scratches then start with 320 grit wet/dry sand paper.After the clearcoat is removed move to 400 then 600 then 800 then polish with a metal polish to a high shine.If you have a drill you can buy a buffing pad for a few dollars that will speed up the final polishing.Good Luck