There's a reamer for that, must be really unusual to need it now - the kind of thing that a lot of workshops will have got rid of or never had. Try a very old-school workshop, or just any good LBS to see if they happen to have it. For instance, where I live, just some of the bikeshops I have within easy reach: Comptons, Parts & Labour, Lee Green Cycles, Rat Race, Seabass, Brixton Cycles, Edwardes ... yada yada. The old school ones are the ones to try first.
There's a reamer for that, must be really unusual to need it now - the kind of thing that a lot of workshops will have got rid of or never had. Try a very old-school workshop, or just any good LBS to see if they happen to have it. For instance, where I live, just some of the bikeshops I have within easy reach: Comptons, Parts & Labour, Lee Green Cycles, Rat Race, Seabass, Brixton Cycles, Edwardes ... yada yada. The old school ones are the ones to try first.