BB facing accuracy

How parallel should you expect the faces of the BB to be?
Quite often people say ‘get the BB faced’ rather than measure your BB and if its more than 0.0Xmm out get it faced – which I would expect to be the logical course of action…
But presumably the threads in the BB are the limiting factor anyway?

the face is faced relitive to the threads 😉

Which are not always straight relative to each other side to side… one of the reasons why I’m far from convinced about the need to face *most* frames.

I think Ideally you’d screw a fake BB into the threads, then pass a large diameter shaft through the middle and use that to face the two sides at the same time, relative to the average thread path of thetwo sides.

That said I never faced my BB and it’s fine and dandy thanks, even with paint on there.

the face is faced relitive to the threads

Most of the tools I’ve seen look like they face relative to the other side of the BB and/or the inner diameter of the tube

None of them look particularly accurate.

coffeking – yep your method makes a lot more sense.

So the current method of doing it is a waste of time and money then… 😈

>So the current method of doing it is a waste of time and money then… ,

Not necessarily – depends what method / tooling was used to thread the bottom brackets

<luddite>
This was never a problem with square taper, octlink etc.
</luddite>

🙂

Not necessarily – depends what method / tooling was used to thread the bottom brackets

Absolutely but then if you don’t trust the faces to be square, why would you trust that the BB threads are straight to eachother?

The tool my LBS uses screws into the BB threads.