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  1. #1
    cab horn
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    Why does the campy bb facing tool also cut a chamfer?

    I'm talking about this tool here:



    Note that it will cut a chamfer into the bb - why exactly do we need this tool? Or is the description wrong? I only ask because the park facer is just a flat mill.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  2. #2
    nice idea, poor execution
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    That doesn't look like the original Campagnolo mill...

    Perhaps it's the mill that chamfers the shell for a Mavic bb?
    Kevin Duffy, Harris Cyclery, West Newton, MA.
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  3. #3
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    As a long-time machinist (started in '71), I can tell you that it is normal for all threads, external or internal to start with a 45 degree chamfer that is 1-2 thread pitches in depth. A straight surface leaves a weak partial thread that is of no value and makes it hard to get the mated parted started in straight.

    Most parts with internal threads define the thread chamfer to be slightly larger than the major diameter of the thread.

    I should add that the tool shown doesn't look like it would do both face and chamfer an ID, but I'd need to see the end of the cutter more closely.

    Also, most facing jobs should only require a small fraction of one thread to be removed.
    Last edited by DaveSSS; 01-06-10 at 07:25 AM.

  4. #4
    Senior Member Chombi's Avatar
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    What DaveSSS said makes sense, but that tool does look very much like Mavic's BB chamfering tool.
    the 80's/90's Mavic sealed cartridge BBs do not use the bike's BB threading to anchor itself to the frame. It does it with just pressure from 45 degree faced lockrings on both ends of the BB that will seat on to the chamfered faced BB provided by the Mavic tool. A nice idea that would have eliminated all need for trying to figure out what threading your BB is when it comes time to change your BB, but I suspect Mavic wasn't too generous with sharing the patent and technology for this with other companies and it "Betamaxed" itself out of existence, plus other better(?) BB designs came to be afterwards ......although,.......don't Phil Wood BBs kinda work the same way??

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    Last edited by Chombi; 01-05-10 at 05:00 PM.

  5. #5
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    Phils use conventional threads.

  6. #6
    Bianchi Goddess Bianchigirll's Avatar
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    I agree with Helomatic I do not think that is the "facing" tool. also what Dave and Chombi said are correct too if you are dealing with a Mavic cart BB (I think VO just came out with one)

    now to answer your question about the too. the 'facing' cutter should not chamfer the BB shell but it is designed to remove paint and "square" the sides of the BB to ensure they are parrallel. this aids in getting the fixed cup tightly into place as well and making the lockring lock tighter. 'facing' and 'chasing' was standard practice on all frame (build up in shops anyway) and I normally did it ( atleast facing) on overhauls. there is also a tool for 'facing' the headtube as well.
    Bianchis '87 Sport SX, '90 Proto (2), '91 Boarala 'cross, '93 Project 3, '88 Trofeo, '86 Volpe, '89 Axis, '79 Mixte, '99 Mega Pro XL Ti, '97 Ti Megatube, , '90 something Vento 603,

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  7. #7
    Senior Member
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    Just a slight correction. Facing makes the face of the BB shell perpendicular to the threads and insures that the face is truly flat, if the cutting is done carefully. I've never had it done to a frame in 25 years and over a dozen frames.

  8. #8
    bike whisperer Kimmo's Avatar
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    The cutting bit comes off, right? Maybe it's missing a flat one.

  9. #9
    Old fart JohnDThompson's Avatar
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    Quote Originally Posted by helicomatic View Post
    That doesn't look like the original Campagnolo mill...

    Perhaps it's the mill that chamfers the shell for a Mavic bb?
    I agree. That looks more like the Mavic cutter than the Campy. The one on my tool kit is not chamfered:



    Look for markings on the cutter; if it's actually a Campagnolo cutter, it should say so:


  10. #10
    Senior Member Chombi's Avatar
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    I'll be glad to get that useless Mavic BB tool out of your hands Pronto!

    Chombi

  11. #11
    Real Men Ride Ordinaries fuzz2050's Avatar
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    Quote Originally Posted by Bianchigirll View Post
    I agree with Helomatic I do not think that is the "facing" tool. also what Dave and Chombi said are correct too if you are dealing with a Mavic cart BB (I think VO just came out with one)
    Just a further off topic interjection, the VO BB fulfils the same niche as the Mavic (reviving frames with buggered up, or obsolete BBs) but does so in a way that doesn't involve cutting on the bike of any sort.

  12. #12
    Senior Member mechBgon's Avatar
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    Quote Originally Posted by Chombi View Post
    I'll be glad to get that useless Mavic BB tool out of your hands Pronto!

    Chombi
    Do you want a Mavic BB mill? We have a couple at work. I've never seen them used once. Tell me how much you want to pay and I'll see if they want to sell one.

  13. #13
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    Quote Originally Posted by chombi View Post
    ...but i suspect mavic wasn't too generous with sharing the patent and technology for this with other companies and it "betamaxed" itself out of existence...
    lol

  14. #14
    cab horn
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    Quote Originally Posted by DaveSSS View Post
    Just a slight correction. Facing makes the face of the BB shell perpendicular to the threads and insures that the face is truly flat, if the cutting is done carefully. I've never had it done to a frame in 25 years and over a dozen frames.
    I have.

    For example, modern bb's like phils and sugino 75's are very intolerant of shell face misalignment. I've seen a fresh steel frame so bad that a standard shimano square taper cart sat noticeably off because of facing issues with a bb.

    At any rate, I have that exact same cutter on that tool, that would be quite a coincidence if it is in fact the mavic tool.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  15. #15
    Senior Member Grand Bois's Avatar
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    How can a Phil BB be "very intolerant of shell face misalignment" when no part of it contacts the shell face?

  16. #16
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    What I do to check for the need to face a BB shell is install the cup and thread it in until it touches a .010 inch feeler gage. Then I use feelers in the .008-.012 inch range to search for high or low areas. If any area exceeds those limits, I'd face the shell. Always remove any paint from the face of the shell, first.

    Anyone installing a Campy UT crank should do this and then measure the BB shell width, which must be 67.2-68.8mm to work properly. A lot of failures result from failure to do one or both of these procedures.

  17. #17
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    Quote Originally Posted by Bianchigirll View Post
    the 'facing' cutter should not chamfer the BB shell but it is designed to remove paint and "square" the sides of the BB to ensure they are parrallel.......I normally did it ( atleast facing) on overhauls.
    I hope you don't do it for every overhaul of frame that has been faced properly once. Once a frame is properly faced, it should never need it again unless it is repainted and then only to clean up any overspray.

    All repeated facing accomplishes is to narrow the bottom bracket shell until the bottom bracket doesn't fit properly. Do it once (only if needed) and leave it alone after that.

    My experience mirrors DaveSSS's. I've built up three Litespeeds Ti frames and a Co-motion steel frame from scratch as well as bottom bracket replacements on several other bikes and none of them has needed facing.

  18. #18
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    Quote Originally Posted by HillRider View Post
    I hope you don't do it for every overhaul of frame that has been faced properly once. Once a frame is properly faced, it should never need it again unless it is repainted and then only to clean up any overspray.

    All repeated facing accomplishes is to narrow the bottom bracket shell until the bottom bracket doesn't fit properly. Do it once (only if needed) and leave it alone after that.

    My experience mirrors DaveSSS's. I've built up three Litespeeds Ti frames and a Co-motion steel frame from scratch as well as bottom bracket replacements on several other bikes and none of them has needed facing.
    I converted a 2001 Gary Fisher Hoo Koo E Koo to Shimano outboard bearing BB/crankset. I brought it to a very reputable bike shop to have it faced and they turned me away, saying it wasn't needed. I removed the paint with a single-edged razor blade and installed. No binding, premature bearing wear, works great. Similarly, I built up a 2001 Ti Spectrum this year with Chris King BB and simply removed the Imron paint with one of my wife's emery boards prior to install (I know that Merlin does a good job of facing BB shells, so I wasn't too worried) and all is well with that bike too. I like the feeler guage method of checking the facing, I'll definitely do that in the future.

  19. #19
    cab horn
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    Quote Originally Posted by Grand Bois View Post
    How can a Phil BB be "very intolerant of shell face misalignment" when no part of it contacts the shell face?


    K thx.
    Last edited by operator; 01-07-10 at 10:11 AM.
    Mes compaingnons cui j'amoie et cui j'aim,... Me di, chanson.

  20. #20
    Old fart JohnDThompson's Avatar
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    Quote Originally Posted by operator View Post
    At any rate, I have that exact same cutter on that tool, that would be quite a coincidence if it is in fact the mavic tool.
    Well, the tool you pictured looks like an amalgam of Campy and Mavic parts. Here's a page showing the Mavic cutter:



    The text describes it as "adaptable to Italian tool holders" by which it likely means "Campagnolo."

    You can see that it bears little resemblance to the Campagnolo #725 bottom bracket facing mill:



    But it does strongly resemble the cutter in your original picture.

  21. #21
    Senior Member vredstein's Avatar
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    Quote Originally Posted by Grand Bois View Post
    How can a Phil BB be "very intolerant of shell face misalignment" when no part of it contacts the shell face?
    He might be referring to Phil Wood external bottom brackets.
    "See, it's not that getting wet is a big deal. Really, it's what you're getting wet with.
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  22. #22
    Great State of Varmint Panthers007's Avatar
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    Regardless of the situation - facing the bottom-bracket is becoming essential with any frame - due to the external- BB's becoming more and more popular. But a notice should be with the bicycle to identify this task having been accomplished.

    I can just see Joe bringing his bike for help - and the BB-shell is 58mm......
    Quote Originally Posted by Cateye View Post
    Only panthers007 is stupid enough to believe that this is a good idea.

  23. #23
    nice idea, poor execution
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    Quote Originally Posted by Panthers007 View Post
    Regardless of the situation - facing the bottom-bracket is becoming essential with any frame - due to the external- BB's becoming more and more popular. But a notice should be with the bicycle to identify this task having been accomplished.
    A competent mechanic can find said notice on the bottom bracket shell itself. If they can't tell the difference between a properly faced bottom bracket shell, and one that needs facing, they shouldn't be anywhere near that tool.
    Kevin Duffy, Harris Cyclery, West Newton, MA.
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  24. #24
    Bianchi Goddess Bianchigirll's Avatar
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    HillRider wether I faced the BB on an overhaul depended on the bike of course. if it was one of our bikes and the faces were relativly clean I ight not. if it was an older mid to higher end bike and I was installing a new BB I certainly would.

    and yes facing is a very delicate operatin like turning brake rotors. actually in most cases very little if any frame material is removed.
    Bianchis '87 Sport SX, '90 Proto (2), '91 Boarala 'cross, '93 Project 3, '88 Trofeo, '86 Volpe, '89 Axis, '79 Mixte, '99 Mega Pro XL Ti, '97 Ti Megatube, , '90 something Vento 603,

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  25. #25
    Senior Member Grand Bois's Avatar
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    Facing a steel frame creates a great place for rust to get started and it can run right up under the paint on the BB shell.

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