Help needed, mavic zap bb chamfer

[matteroftaste]

Hi all, I have an old frame with bad bb threads and go my hands on a mavic zap bb that tightens onto the bb shell by itself.
However, after reading up on how to install it, I realise I need to cut a chamfer into each side of my bb shell for it to stay put properly. The only issue is that I have no access to any tool that might work, my lbs were understandably at a similar loss.
Any ideas on how I could save this frame?
Much obliged to any replies.

 

[Rod_Saetan]

If it helps your search the Mavic BB that requires that tool is not specific to the Zap grouppo, but was available for Road and MTB chainsets throughout the 80s and 90s.

Oh, and I too would really like to borrow that tool for a bike, or I'd happily buy the tool if anyone wants to get rid.

 

[mdvineng]

If your near manchester I can do it in a lathe

 

[syncrosfan]

There is a specialty Mavic tool for that chamfer (it's 45 degrees per side) that looks like a BB facing tool but with the 45 taper instead of being straight. Those tools are rather rare and any modern bike shop won't have them. Try your luck with a shop that does work on old school bikes. I had the same dilemma with my bike but I had access to a machine shop at that time and I had some time on my hands and was too cheap to spend 200 plus bucks on the proper Mavic tool. As it happens any industrial counter-sink has the same chamfer angle (90 degrees altogether) and we had a large diameter tool like that in the workshop, so I made a specialty BB chuck on the lathe in order to be able to get my frame square in the milling machine. After lining up the center of the BB it was one easy quick machining step to get the chamfers in.
Long story short, if you have access to a machining shop, it can be done without the Mavic tool but there's a lot more work involved making a fixture to bolt down your frame squarely onto a mill (can be done with a lathe too in a pinch).

 

[matteroftaste]

Re:

Solved! I found a bike shop that can do it for £20, right round the corner from my dads place. They have the original tool, but admitted to not using it often.