Help Me Find a French BB Tap
 

It occurs to me that despite all of my bike tools, and my delusions of having enough of them, I've come up wanting. Recent changes in tastes and some customer needs has led me to want for a 35x1 RH tap for French bottom bracket threading. I cant find one anywhere. Does anyone know of a source?

Perhaps also post in frame builder's thread??

Where are you located?

Wayne Bingham at Velo-Classique is a VAR importer. If he doesn't have the tap in stock, he likely could order it for you.

https://www.facebook.com/pages/categ...4625401059577/

Far be it from me to dissuade anyone from buying tools but with these in particular considering the cost, I ask myself if the need really warrants it.

I have never failed with these.

As a lifelong technician/mech, ASE, fomoco Senior Master, 35yr motorcycle drag racing and bikes since 12yrs with probably $100k in tools have always felt that taps are too sharp for thread restoration work and may take off too much material where there is little or none to spare, especially if it goes wrong when the tap digs in. ;)

I use the pick to scribe the threads clean then chase with the modified cup and anti-seize.

https://cimg3.ibsrv.net/gimg/bikefor...b6deccc838.jpg

I thank you for your suggestions, but I've already made these sort of thread chasers, and I have dozens more of various pitch. As a lifelong second-generation machinist and an aircraft mechanic, I've never had a tap or die "go wrong" when threading. Care and skill plays a huge part in this, because seriously - you don't get to that point overnight. All things considered, I've made my fair share of buggered threads, surely, but that was under my dad's tutelage in his shop. Nowadays, I'm confident in my skills. That said, I'm still in search of a tap.

Not bad idea, but is anyone reproducing french-threaded BBs these days?

New Hampshire, USA

Thanks! I will check this out! :thumb:

too far in the pandemic period to drop by and chase and face for you.
Southern California

:thumb: Probably should have known I guess.

You would be one of the few here that can truly wield the regular taps with proper authority, seen plenty of destruction when it was not so, especially in these types of cases.

All that being said, under the gun, at the track, on the road and left to my own devices many times, I've cleaned up plenty of my own and others messes without any actual formal training, albeit crudely at times but always successfully in the end. ;)

If you don't need it to be "piloted" and completely co-axial with the other side of the BB, why not order an m35x1 tap on Ebay from China? It will get here eventually, and I bet it would work just fine. Cheap enough to gamble on, too.

Many thanks to jonwvara for tracking one down for me. Its a Chinese tap on Amazon, and I swear that I've searched for the very same thing on Google. This is where I really wish I had a lathe again, because I would turn down a threaded guide and have the Chinese tap hollowed out by EDM. I may have to re-buy my shop equipment because my brain is realizing many new business opportunities. I'm retired, so I shouldn't be working this hard anymore! Cant help myself! :rolleyes:

...+1. This is what I did. A plug tap works fine for established threads as long as you use it with awareness and some caution. I think I ordered mine on Amazon.

A piloted tap set out to Italian would likely work as well

+2 to chase olden threads. Got mine on Ebay for $22 w/ shipping

French: 35 x 1mm
Italian: 36 x 24tpi

indeed - 1mm difference and 24tpi over the 25.4tpi

seems like 30-40 years ago this was done for blitzed French and considering if I heard about it then it must have been fairly common knowledge

...it is still done for any of the other BB threadings that are smaller when they are beyond redemption. I have done it myself recently, with a rusted BB in English threading without much threading left. But it's pretty hard on your taps to run an Italian set through a French BB without first reaming it out a little. I guess you can do it, but it's not standard practice.

Bicycle Research made a reamer/Italian tap set for this purpose. Perhaps a local bike shop still has one?

I have the reamer to go from Eng/ISO or French to Ital. It goes on my Campy BB tap holder, so I can run the other side tap in (assuming only one side is bad), then ream and tap with confidence that it will be co-axial with the other side.

Recently I reamed and tapped one side to Ital for a guy with a buggered up French thread. I offered to do the other side too, but he said no thanks, so that bike will go off into the future with Ital one side, French on the other. That may cause some mechanic to scratch his head some day!

There are also adapters with Ital thread on the outside and Eng/ISO thread on the inside. Yes, even one with a left-hand thread Eng on the inside, with a right-hand thread Ital on the outside. (A marvel of machining -- whatcha call a "howdy doodat?") You can buy them from Ceeway in the UK, not sure if there is an American stockist. Go here and scroll to the bottom, look for "Art.606." (Text search won't find it, it's an image of text. Weird website.)

In theory, they could make that same part with a French thread on the inside, but I doubt they do. Too much of a niche market these days, and getting smaller with each passing day. I have some of those adapters, but haven't used them yet. I assume you Red Loctite the adapters into the frame, then grease the threads on the cup, so the adapters won't seize onto the cups.

Anyhoo, not for the OP but if anyone in the Seattle area needs BB threads tapped and/or reamed, I have Eng, Ital, French and Swiss, plus the chamfer for Mavic unit BBs. Low-mileage sharp Campy taps, which are the best I know of, with the most precise pilots. Oh oops I lie, my Swiss tap is not Campy, it's Hozan and not piloted. But I have found you can start with the Campy Eng left-hand thread tap, cut just the first few threads, then the Hozan Swiss will follow those. The thread pitch difference doesn't show up in the first few threads, so results are indistinguishable from The Real Thing.

I'm pretty strict about not allowing my taps in a frame if there's sandblasting sand or other abrasives in the threads, or if there's chrome plating in there. Luckily chrome doesn't really like to go inside the shell, more than about the first couple threads. But I digress.

Mark B in Seattle

Something I'm pretty sure you know, BITD I was taught that if you did something non-standard like this, leave a note inside the BB so that future mechanic will know. Odds are they wouldn't double check the markings on the BB.

Agreed. This procedure isn't an option for me anyway.

The bike I did that on was being restored by one of the top vintage restorers around here -- I won't out him, but you (Gugie) know him. I left any note-leaving to him. But honestly, if you have to take the BB out to see the note, any mechanic worth his salt would probably already have noticed one cup is 1 mm bigger than the other.