Thread chasing for Campagnolo derailleur hanger

Hello,

Does anyone have any advice for cleaning the threads out on a campagnolo RD hanger?

I had a frame resprayed but it came back with paint on the threads of the hanger.

It's an early 1970s frame and from what I understand, I need a 10mm x 26tpi tap - but these aren't easy to find. Anyone got an idea where to look?

I read somewhere that it's possible to use a campagnolo rear axle to chase out the thread if you screw it in carefully from the back of the hanger. It doesn't sound like a terribly good idea though.

My local bike shops are pretty clueless when it comes to old bikes, they either can't or don't want to help. I could send it back to the people who sprayed it but that could take weeks.

Cheers for any advice,

Johnny

You need an M10 x 1.0 mm tap. All drop outs have the same thread as far as I know.

I have one in the shed of dread I can post if you want to borrow one?

One thing I learnt from having a frame repainted is put bolts in or cover the threads.

Clearing paint out of the downtube gear leaver bosses was a right PITA ...

Thanks chaps,

@Robbied: It would be great if I could borrow your tap, if you don't mind posting to Belgium. If PM your details I can pay the postage in advance. Do you want some kind of deposit in case anything goes wrong?

@Montello: Yes, that sounds horrible. Luckily my frame was too old to have braze ons. Presumably you also have to tell them to leave any bolts in so some clever dick doesn't remove them...

Johnny

How bad is it? How much damage can be done by er, forcing the bolt through? Or are you worried about the paint around the hole flaking off?

agentorange":1mreitze said:

How bad is it? How much damage can be done by er, forcing the bolt through? Or are you worried about the paint around the hole flaking off?

Click to expand...

Problem is I don't know how much damage could be done,
but a stripped hanger thread or derailleur bolt or (as you say) flaked off paint is never going to be fun. The paint is fairly thick too, so I don't know if forcing the bolt through would work. I think I'd prefer to try to do it properly, this time at least

Even with the tap, you should clean off the paint around the start of the thread. Otherwise it could start a new thread in the paint not follow the original.

I'd lightly run a countersink onto the hole (neatest), or run a knife around the edge of the hole first.

All the best,

metric threads in a 70"s Frame - I'm not sure on that so be careful as metric thread angles differ by 5 degs from Imperial. Imperial 55 degs & Metric 60 degs.

One other tip: if you have space, try tapping from the inside of the dropouts: if you get it wrong it will not be curtains for the frame. But firstly I would use a needle and sharp knife tip to clear as much of the paint as possible.