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Discussion Starter · #1 · (Edited)
Hello,

I'm not building a frame but I'm fixing a carbon frame that has a small chunk of carbon missing from inside the BB shell. What I did was a mixed up some West Systems 105/207 epoxy and I dabbed the epoxy to fill the carbon hole I then wiped a very, very thin layer along the outside of the BB where the bearings will sit. My thought was when I sand the epoxy down where the hole was I'll be able to tell when I'm either all the way through the epoxy or just close to it and then I can sand the entire way around just a bit to remove most of the fine layer of epoxy I wiped around the entire BB shell.

But before I do so, are there any tips for sanding the inside of this BB shell perfectly smooth and true? As it stands I just planned to sand down the area with the hole which has just a slightly raised spot from the epoxy even with the rest, then I planned on running the sand paper around the entire bb shell nice and lightly and evenly just to knock down whatever epoxy may be there from wiping it on. I doubt the epoxy I wiped along the shell really added any thickness or maybe just a minuscule amount it more seemed to seep into the carbon and just seal it as apposed to adding thickness onto. So I'm hoping sanding the one spot by eye and feel and then just lightly running the sandpaper over the rest of the shell will be good enough for a perfect fit with my bearings.

Any help is appreciated.

EDIT: I just found a 40.98 reamer. Perhaps I should use that. It will cost a few hundred dollars though, so not sure if it's worth it if sanding it would be just fine. But the reamer would be good peace of mind and certainly avoid a creaking BB.

Thank you,
 

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Just epoxy? Use a reamer. Anything more than minor CF removal will mean that you need to have the reamer sharpened after a few bottom brackets/whatever, since carbon fibers are quite hard on cutting blades.

The Park head tube reaming kit is adaptable to ream press-fit bottom brackets, while maintaining concentricity, which is not guaranteed by hand.
 

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Discussion Starter · #5 ·
im a do it 110% all the time type of guy so I already epoxied it and purchased the reaming and facing tools to do the job right. now I can be confident my bb bearings are 100% aligned and not only will it guarantee no creaks but definitely be longer lasting and smoother. I actually did some measuring and it appears even a stock yeti isn't faced 100% correctly, so I'm actually glad I went this route. now ill actually be able to face my headsets as well. and if I get a tool for the disc brake mounts ill be able to prep/face my own bikes at home which is awesome!
 
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