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Bike skop faced bb shell

Old 07-01-08, 05:08 PM
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perfex
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Bike skop faced bb shell

Well I needed a new BB for my cyclo cross bike cause of a creak ,

Anyway I did alot of the work my self since I been going there along time, well the threads needed to be chased so he took out that 400$ park tool chased them, that came out nice, but then he wanted to face it, well the aftermath of it was variable chizel type marks on the shell outer surface, I have never done it my self but it does not seem right, I would think it would have a smooth finish on it.

Anyone done this type of thing to know howit would be done, or if it was done wrong?
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Old 07-01-08, 05:20 PM
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It should be smooth, with no indentations. Sounds like his tool is dull or he just doesn't know what he's doing, if you don't apply the right amount of pressure or try to do it dry you can get gouges like that.
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Old 07-01-08, 05:27 PM
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He was putting massive amounts of pressure on it. He did use cutting oil though

whats your take on it, will it hurt the functionality ?

Should it be faced again to make it smooth?

Last edited by perfex; 07-01-08 at 05:30 PM.
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Old 07-01-08, 08:08 PM
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Originally Posted by perfex View Post
He was putting massive amounts of pressure on it. He did use cutting oil though

whats your take on it, will it hurt the functionality ?

Should it be faced again to make it smooth?
It should be smooth. I'd be worried about taking too much material off at this point to make it smooth. Does your mechanic know what he's doing?
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Old 07-01-08, 09:16 PM
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Yeah, he pushed too hard so that where he stopped the teeth were dug in and left pits. Pits aren't a huge deal, you just want a flat surface with no points that are too high, so pits that are a little too low are no biggie. If there are high points where it dug up a burr I would go after those with a whetstone or a file.
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Old 07-02-08, 03:31 AM
  #6  
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It's actually not pits, but rather a jagged surface that goes up and down, kinda like saw-teeth. Yeah, he was pushing way too hard. This caused the tool to dig deeper into the metal than necessary. Then it would actually break off a piece rather than shave it off and the tool would skip. This leads to the chiseled marks you see. Find a better shop with people who actually know how to use their tools.
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Old 07-02-08, 05:16 AM
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A smooth finish is not necessarily so.

Quoting from Barnett's Manual on BB facing:

"Facing-tool chatter is the tendency of the facing tool to bite and jump at rapid frequency. This tendency leaves
a series of radial lines in the face of the bottom-bracket shell. These radial lines are a cosmetic flaw, not a mechanical flaw. To some degree the chatter marks are preventable, but circumstances outside the control of the mechanic make (sic, should be "may") make chatter marks unavoidable at times. Proper facing techinque can reduce the likelihood of chatter occuring, but if the type and hardness of the bottom bracket shell material is not compatible with the design of the facing tool, then chatter cannot be prevented."

And further:

"Fine modulations of the cutting pressure and slower cutting speed should be used to prevent or reduce a phenomenon called chatter. Chatter is the tendency of the tool to bite and jump at a rapid frequency, resulting in a chattering feeling and noise from the tool as it cuts. For every metal there is an optimum pressure; try reducing or increasing the pressure to eliminate chatter. If chattering occurs it will leave a series of radial lines....

"Chatter cannot always be prevented, but it can be minimized by modulating the cutting pressure and speed. In addition to pressure and speed being factors, the design of the facer teeth has to be suitable to the particular hardness of metal being cut. When the design of the facer teeth is too aggressive for the hardness of the metal being cut, then some chatter is inevitable and must be lived with."

I'd say live with it.
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Old 07-02-08, 05:27 AM
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Originally Posted by perfex View Post
Well I needed a new BB for my cyclo cross bike cause of a creak ,

Anyway I did alot of the work my self since I been going there along time, well the threads needed to be chased so he took out that 400$ park tool chased them, that came out nice, but then he wanted to face it, well the aftermath of it was variable chizel type marks on the shell outer surface, I have never done it my self but it does not seem right, I would think it would have a smooth finish on it.

Anyone done this type of thing to know howit would be done, or if it was done wrong?
If the marks are a lot of smallish radial lines, then it is called "chatter marks". The facing tool bites into the metal and then jumps causing the chatter marks. Barnett's Bicycle manual calls chatter marks cosmetic flaws, not mechanical flaws. It also says, that while chatter marks usually can be prevented, there are some circumstances were it is unavoidable that the facing tool causes chatter marks.

So don't worry about it and don't take it as a sure sign that your LBS is incompetent.

--
Regards
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Old 07-02-08, 05:02 PM
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If you could post a photo of the shell and marks, the experts would be able to opine on whether the marks are just chatter marks or an actual functional/competence problem.
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Old 07-11-08, 07:35 PM
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Sorry for the late response had to order the tool as I didn't have it, I will try to upload some more






File it down, get it refaced ?

Last edited by perfex; 07-11-08 at 08:11 PM.
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Old 07-11-08, 07:52 PM
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Oh man.
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Old 07-11-08, 08:02 PM
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indeed
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Old 07-11-08, 10:15 PM
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Yikes!
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Old 07-11-08, 10:20 PM
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Originally Posted by perfex View Post
Well I needed a new BB for my cyclo cross bike cause of a creak ,

Anyway I did alot of the work my self since I been going there along time, well the threads needed to be chased so he took out that 400$ park tool chased them, that came out nice, but then he wanted to face it, well the aftermath of it was variable chizel type marks on the shell outer surface, I have never done it my self but it does not seem right, I would think it would have a smooth finish on it.

Anyone done this type of thing to know howit would be done, or if it was done wrong?
Looks like more than "chatter" with the appearent depth of those marks. Should be able to get those marks out with a sharp tool and taking their time. Looks like the shop has some explaining to do. They should have put the new BB in without facing the BB the old "facing" was mainly to remove any paint from the BB face and not much metal.

Last edited by Deanster04; 07-11-08 at 10:26 PM.
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Old 07-11-08, 10:34 PM
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Sharp tool?
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Old 07-11-08, 10:41 PM
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Originally Posted by perfex View Post
Sharp tool?
as in teeth...looks more like there was an attempt to take too much material off too fast. Honestly I have only steel bikes and have never used the tool on anything but steel however, there may be different facing bits for different materials. I have had my tool for a very long time...actually pre-aluminum.
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Old 07-11-08, 10:43 PM
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the frame is scandium/carbon

I was thinking of using a fine file, just want to keep the surface level, would like to find a file as wide as the shell, but if I cant think a cross method would work , still keeping the surface level?

I am also unsure if it affects anything, I did ride it didnt seem to be any problems that I know of, but its there even though I cant see it bothers the hell out of me
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Old 07-11-08, 10:59 PM
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Originally Posted by perfex View Post
the frame is scandium/carbon

I was thinking of using a fine file, just want to keep the surface level, would like to find a file as wide as the shell, but if I cant think a cross method would work , still keeping the surface level?

I am also unsure if it affects anything, I did ride it didnt seem to be any problems that I know of, but its there even though I cant see it bothers the hell out of me
DEFINITELY NOT!!!! If anything take it to a local bike builder and have them try. Anything you do will compound the problem unless you use the tools that will ensure a parallel face. Good luck. I would talk to the shop owner and get a second opinion from other competant shop owners. Don't bad mouth the guy that did the damage it won't help.
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Old 07-11-08, 11:28 PM
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I'd be speaking to the manager of that shop!
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Old 07-12-08, 02:11 AM
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Originally Posted by perfex View Post
the frame is scandium/carbon

I was thinking of using a fine file, just want to keep the surface level, would like to find a file as wide as the shell, but if I cant think a cross method would work , still keeping the surface level?

I am also unsure if it affects anything, I did ride it didnt seem to be any problems that I know of, but its there even though I cant see it bothers the hell out of me
If it were me I would want a new frame. That is the worst facing job I have ever seen.

If it is torqued to spec, just see how it goes. I would not do anything else to the frame. How much under-size is your frame? Maybe you can get store credit and make it win-win.
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Old 07-12-08, 03:46 AM
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Not only is it a really bad job, I think the tool must be broken. It appears that the surface is also beveled slightly in a convex shape in addition to the aggressive bite marks.
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Old 07-12-08, 03:47 AM
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Well not sure if the shop would go for the new frame, I cant find this frame anymore anyway, its a 59 cm Bianchi Cross Veloce, 2008 didn't even sell the frames, I have heard 2009 is an all carbon frame (from guy @ Bianchi USA)

Do I need a new frame? will it have adverse affects on the bottom bracket? or is it merely a cosmetic problem? I am not sure
suggestions on fixing the problem would be nice, there is only one shop where I live, and they did this.

Would refacing fix the problem, or would it take off too much metal ( if it were done right that is )

I am sure If I would go back since I have been going there for along time, they would let me use the tool my self or even redo it or is it unfix able?

Last edited by perfex; 07-12-08 at 03:51 AM.
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Old 07-12-08, 04:54 AM
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It does look worse than normal chatter.

However, the reason for facing is to ensure the opposite sides of the BB are parallel to each other. As suggested, if the bearings face up to it and the axle runs truly and freely, you might get away without having to do any extra work. You might need to check the torque on the bearings from time to time.

As menionted already, doing anything like filing down by hand runs the very good chance of running the surfaces out of true with each other. The problem with doing the facing again also is that the amount of metal you will need to take off will drop the BB dimension down by anything up to 2mm, and that might make BB bearing fitment chancy.

I am interested to know what the shop guy who did the work said when you pointed out the chatter marks.
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Old 07-12-08, 06:09 AM
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I trusted the guy, hes done work for me before, I held the bike while he did it, when it came off, I saw a concerned look in his face, but he said atleast its parallel now.

I was still concerned but having not done the procedure before, I did not know

Thanks for the advise and time guys, I will talk to the owner and see what is going to happen

Here are the installed photos of each side of the shell
its 67.77 mm as per my micrometer




Last edited by perfex; 07-12-08 at 06:32 AM.
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Old 07-12-08, 08:05 AM
  #25  
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It's certainly a hack job. That's a shame. However, if the the facing is square on the "peaks" all the way round, it should work okay. If it really bothers you, find someone else, more skilled, to do it over in a lathe or drill press.
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