removing finish from xtr cranks?- Mtbr.com
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  1. #1
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    removing finish from xtr cranks?

    no one on the general board responded...

    anyone have experience removing finish from xtr cranks? the mega 9 gunmetal grey variety?

    thnx.N
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  2. #2
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    Steel wool?

    Quote Originally Posted by ncj01
    no one on the general board responded...

    anyone have experience removing finish from xtr cranks? the mega 9 gunmetal grey variety?

    thnx.N
    I removed some paint/anodizing with steel wool on the weekend. Perhaps that will work?
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  3. #3
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    I did some LX cranks

    Started with a semi rough sandpaper flapper wheel then worked my way down to very fine sandpaper and finished up with soft buffer and polish. Maybe 15 steps before I was finished. Took forever but they looked pretty cool. A guy down the street does custom motorcycle stuff and he helped me get started. Said the key is to be very light and even with the flapper wheel when you first start or you will get waves and they show up when you polish.

  4. #4
    Witty McWitterson
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    Why? That's the best finish that shemano has come out with!
    Just a regular guy.

  5. #5
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    I've had really good luck using the side of my shoe, although admittedly it was only localized. 3M makes scotchbrite sanding discs in different grades (grits?), might want to experiment with those. I've used them on both stainless steel and aluminum and they leave a nice finish. You have to be careful with the amount of pressure you use though, 'cause those pads will take some metal off if you press too hard...

  6. #6
    jl
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  7. #7
    EPO
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    No good A SMALL LESSON ON Al SURFACE TREATMENTS.

    I would not purpusely do this unless it is anodized PURPLE! but seriously this will kill the life of the crank set.

    Anodizing raises the hardness~(strength) on the surface to a certain case depth. Sturcturally speaking this is mainly done for wear purposes(think abrasion). You wear througth the naked 6061 T6 or 7075 T6 faster than butter if you expose more of it, as anodization increase the hardess 150%. Increased wear may cause possible stress consentration(s) at the surface, that cracks like to grow in.

    Other than anodization being removed, you may remove the shot peen surface treatment.The stress levels in a bending canilever(crank) are the greatest at the surface, this is one reason why manufactures shot peen. Shot peening also increases the surface hardness, but by the cold working the grain structure of the cystal structure, and making an crystal structure which will retard fatigue crack propagation. I believe the XTR crank set is shot peened, so if you remove the anodization from the surface without knowing how deep you are going, you may buff below the shot peen case depth. Creating more paths at molecular and marco scale for surface cracks to start from and GROW.

    If you do this though, I would recomend you to try to bring back drilling holes in your crankset with a beer in hand, 70 style. That would look cool too, but do nothing in the functionality dept.


  8. #8
    EPO
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    Caution;  Merge;  Workers Ahead! You Can't be Serious!!!!!!!!

    Read the bottom of the first thread....lol.

    Dude DO NOT PUT THEM IN THE OVEN under any curcumstances if you plan to ride them! Greeze, the heat treatment will be gone faster than a raped date. Sorry, but heat treatment of 6000 series takes place at temperaures at less than oven cleaning temps ~900°F... and the melting temp is near 1500°F. Don't quote me on the temps, most of us are not Material Engineers, but that is the most oblivious thing I have heard in a while.

    Ahhhh...check that I'm opening my own heat treatment services as soon as I can jam my bike frame into my oven...any takers?


  9. #9
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    Quote Originally Posted by EPO
    I would not purpusely do this unless it is anodized PURPLE! but seriously this will kill the life of the crank set.

    Anodizing raises the hardness~(strength) on the surface to a certain case depth. Sturcturally speaking this is mainly done for wear purposes(think abrasion). You wear througth the naked 6061 T6 or 7075 T6 faster than butter if you expose more of it, as anodization increase the hardess 150%. Increased wear may cause possible stress consentration(s) at the surface, that cracks like to grow in.
    Anodizing raises the hardness on the surface but decreases the ductility, reducing the fatigue life of the part. The hard surface provides a place for fatigue cracks to initiate, and in fact, is riddled with microcracks like a desert floor even when new. As Jobst Brandt often points out, it acts like a scab on your elbow or knee, it cracks when you bend it, and it can reopen the healing skin below.

    In other industries, anodizing is used for cosmetic reasons and for resistance to oxidation, but only in the bicycle industry do people believe that it increases fatigue resistance.

  10. #10
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    When I was a BMX'er back in the 80's, I went through lots of color combinations (red, blue, checkerboards, etc). I finally decided I wanted my bike black and chrome/silver. I can vouch for the oven cleaner - it worked for me. This is not a joke...make sure it's Easy Off Heavy Duty - none of the non-toxic stuff either. We tried several brands and that was the one that worked. Spray the parts and let them soak. The anodizing will start to come off. It may take several coats. Once you have removed it completely, hit the parts with some Hapich Simichrome or Mothers wheel polish. This too will take several applications. A buffing wheel on a drill press or grinder really helps. Avoid sandpaper, steel wool, or anything abrasive as you will scratch the aluminum and getting a smooth chrome finish will be harder. Don't know why more manufacturers don't produce cranks with a non-anodized polished finish (the silver cranks you see have a silver anodized coating). I have a set of Cook Bros E2's that are polished. They're great, anytime they start to look dull, I take out the metal polish and 15 minutes later they look like new.

  11. #11
    EPO
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    You are correct in a Lab situation, but out in the mud is different.

    Quote Originally Posted by slim_pickens
    Anodizing raises the hardness on the surface but decreases the ductility, reducing the fatigue life of the part. The hard surface provides a place for fatigue cracks to initiate, and in fact, is riddled with microcracks like a desert floor even when new. As Jobst Brandt often points out, it acts like a scab on your elbow or knee, it cracks when you bend it, and it can reopen the healing skin below.

    In other industries, anodizing is used for cosmetic reasons and for resistance to oxidation, but only in the bicycle industry do people believe that it increases fatigue resistance.
    I'm not claiming anodization increases fatigue life, but wear life. I totaly agree with what you are saying: the desert like appearance of anodization, and reducing the fatigue life of the part. You are correct in a clean lab situation, but out in the mud is different. I have seen my buddies wear some serious grooves into the side of their cranks even with this suraface treatment on. Kinda like the Doors' song "Break on through to the other side", where the aluminum is soft. This is the reason why designers call this out on mountain bike cranks, you do not see it on road cranks do you? No mud, no ano. Depending of the stress levels seen on the surface, anodization maybe out of the question. Another thing being a large company, Shimano would not release any produce that would result in a reduction in life, for a little oxidation prevention. Ano is good when applied correctly, and it is on the cranks.

    Happy polishing and don't huff to much oven cleaner guys, your ideas are allready shaky as going back to 26in wheels.

    -EPO


  12. #12
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    Quote Originally Posted by EPO
    I'm not claiming anodization increases fatigue life, but wear life. I totaly agree with what you are saying: the desert like appearance of anodization, and reducing the fatigue life of the part. You are correct in a clean lab situation, but out in the mud is different. I have seen my buddies wear some serious grooves into the side of their cranks even with this suraface treatment on. Kinda like the Doors' song "Break on through to the other side", where the aluminum is soft. This is the reason why designers call this out on mountain bike cranks, you do not see it on road cranks do you? No mud, no ano. Depending of the stress levels seen on the surface, anodization maybe out of the question. Another thing being a large company, Shimano would not release any produce that would result in a reduction in life, for a little oxidation prevention. Ano is good when applied correctly, and it is on the cranks.
    The anodization on cranks and rims is very thin and wears off with a little abrasion. The brakes wear the ano off rim sidewalls in one wet ride or a couple of dry ones, while the rims wear on for thousands of miles. My 2002 black ano cranks had bare aluminum shoe marks in a month. It's clear to me that neither application of anodization appreciably extends the wear life of the part.

    As far as Shimano's specifications go, you don't have to look hard to find an example of a bike company trading fatigue life for appearance. In most cases, the designers don't even recognize they are making a trade off. In the case of anodized cranks, very few will be used long enough to fail, so they're durable enough from Shimano's point of view.

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