Tapping a BB thread help

[ishaw]

I have a frame that is nos, but was never finished. It only has a thread tapped on one side of the BB. I need to get a thread tapped into the other side. Anyone got the tools and know-how to do it?

It's an alloy frame, and will probably be built up with m952 cranks so a thread less/frame saver type BB isn't an option.

It's also not had the bottle boss riv-nuts added, so need to get this done too.

Any help or directions to help gratefully received.

 

[scant]

The bottle boss riv nuts are pretty easy to do yourself. you can buy the riv-nuts off ebay & make your own tool with an old nut & bolt, rather than the proper tool. theres plenty of how to vids on youtube.

I'd be inclined to suggest a frame builder for the bottom bracket thread, or at the very least a well repped bike shop that has previous experience & the proper tools

 

[ishaw]

Re:

Thanks, I'll look into that.

I've tried my local bike shops and none do thread tapping. One says they can, and have the tools, but also admit they haven't done it for years so would be at my own risk.

With the rest of the restoration on the go, and the uniqueness of the frame, if it gets wrecked the rest is useless due to it being a nuke proof reactor.

 

[focomat 1c]

Re:

Your only safe bet is a frame builder

A bike shop will almost certainly never have tapped a complete thread,
as they would normally only ever need to clean up an existing damaged or
corroded thread

A few years ago I had a problem with opposing B/B threads not being in
correct alignment which I solved by a visit to Argos ( my nearest frame
builder ) They re - tapped the thread on one side and solved my
problem

The normal approach is to screw a threaded guide into the existing B/B thread .
This guide has a hole bored through the middle . The tap to be used on the
opposite side has a rod , machined to be a very close fit in the hole , ahead
of the cutting edge of the tap . This ensures that the second thread is cut
exactly parallel to the first

 

[ishaw]

Re:

Resurrecting this thread as the project is now gaining momentum. I should have the bulk of the work done soon, but can't progress without the BB threads being done.

Can anyone suggest a frame builder around the Epsom area that they would trust to do the job?

I'd hate to get this far only to have the frame ruined by a bad job.

 

[gradeAfailure]

Re:

Chas Roberts' son Geoff is in Hailsham - not too far?