Stripped BB threads

In article <[email hidden]>, [email hidden]
says...

Quoted message said:

A friend of mine has stripped threads on the adjustable cup side of his
English bottom bracket.
The advice I have given is to fit a Stronglight threadless BB but I have no
experience of these are they successful or is there any other answer

Take it to a shop with the proper tools to make the frame italian threaded.
-------------
Alex

peter.kidwell said:

A friend of mine has stripped threads on the adjustable cup side of his
English bottom bracket.
The advice I have given is to fit a Stronglight threadless BB but I have no
experience of these are they successful or is there any other answer

Have someone run a BB tap through it first - it may be salvageable. If
this fails then a threadless BB is the easiest and neatest solution.

Of course, if it's a *really* fine lugged steel frame you could have a
new BB shell brazed in - it costs 90-110UKP over here, plus the
inevitable respray.

Quoted message said:

From: Zog The Undeniable

Quoted message said:

Have someone run a BB tap through it first - it may be salvageable.

That's the thing to try first, by someone using real thread cutting oil (such
as Rigid) and a good tap. Success also depends on which BB is being used. I had
a stripper that worked fine for years with Campy steel cups, not at all with
Phil rings.

Quoted message said:

If this fails then a threadless BB is the >easiest and neatest solution.

I'm using a Mavic threadless BB with a Campy C Rec crank that has done just
fine, with the axle nominally being a few mm's too long (somewhat moveable
side-to-side). The BB shell must be (correctly) chamfered for the tapered cones
to work; there is a "Mavic tool" for this job. I understand that the Mavic BB's
are out of production but that Stronglight makes an identical setup. --TP

peter.kidwell said:

A friend of mine has stripped threads on the adjustable cup side of his
English bottom bracket.
The advice I have given is to fit a Stronglight threadless BB but I have no
experience of these are they successful or is there any other answer

Those work fine if you can get the right dimensions. Like
the Mavic and KSS units, the two sides screw together,
obviating the frame threads.

It's also straightforward to fill in new metal and cut a
fresh clean thread in a steel frame but you'll necessarily
lose paint .

Sort of like this but inside out:
http://www.yellowjersey.org/FORKTHRD.JPG

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Quoted message said:

It's also straightforward to fill in new metal and cut a
fresh clean thread in a steel frame but you'll necessarily
lose paint .

Obviously, your threaded steerer example is different, but why would one
lose paint on a BB shell from a braze-fill? Does the brazing material spill
over to the outside of the BB shell? Can it be brazed work-side-up so that
the brazing stuff goes down to the other side of the BB (also easily tapped,
no?)?

--
Phil, Squid-in-Training

"peter.kidwell" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

A friend of mine has stripped threads on the adjustable cup side of his
English bottom bracket.
The advice I have given is to fit a Stronglight threadless BB but I have
no experience of these are they successful or is there any other answer

PK

Some of my cycling buddies have said to use oversize cups, are these still
available.
The frame is a Woodrupp (Small English Builder) Renolds 531 and very nice
too.

PK

Phil said:

Obviously, your threaded steerer example is different, but why would one
lose paint on a BB shell from a braze-fill? Does the brazing material spill
over to the outside of the BB shell? Can it be brazed work-side-up so that
the brazing stuff goes down to the other side of the BB (also easily tapped,
no?)?

I think playing the flame of a brazing torch on the BB shell may ruin
the fine finish ;-)

Quoted message said:

From: "peter.kidwell"

Quoted message said:

Some of my cycling buddies have said to use oversize cups, are these still
available.
The frame is a Woodrupp (Small English Builder) Renolds 531 and very nice
too.

The Holdsworth I still have, the threads were mangled by someone (ahem) putting
the wrong tap (English threads) in the left side when the bike was new. Live
and learn. Needless to say there is a lot of metal missing, but a second
"chase" with the correct tap left enough threads that there has never been any
trouble with Campy Nuovo Record steel cups.

You need a sharp tap and "real" cutting oil, *not* motor oil or whatever. Rigid
dark oil (plumbing supply house) is the best IME for steel. --TP

"Zog The Undeniable" <[email hidden]> wrote in message
news:4182109f.0@entanet...

Quoted message said:

Phil said:

Obviously, your threaded steerer example is different, but

why would one

Quoted message said:

Quoted message said:

lose paint on a BB shell from a braze-fill? Does the brazing

material spill

Quoted message said:

Quoted message said:

over to the outside of the BB shell? Can it be brazed

work-side-up so that

Quoted message said:

Quoted message said:

the brazing stuff goes down to the other side of the BB (also

easily tapped,

Quoted message said:

Quoted message said:

no?)?

I think playing the flame of a brazing torch on the BB shell

may ruin

Quoted message said:

the fine finish ;-)

But this does bring up a good point. Since it is just thread
repair, maybe a liquid metal or some wonder-bondo product could
be used instead of brass. This probably would gum up the tap,
but what the heck, you would save your paint. I do not know if
there is anything on the market tough enough to take a lasting
thread, but wonder products seem to appear on a daily basis. --
Jay Beattie.

Quoted message said:

From: "Jay Beattie"

Quoted message said:

But this does bring up a good point. Since it is just thread
repair, maybe a liquid metal or some wonder-bondo product could
be used instead of brass. This probably would gum up the tap,
but what the heck, you would save your paint. I do not know if
there is anything on the market tough enough to take a lasting
thread, but wonder products seem to appear on a daily basis. --

J-B Weld? <g>

Quoted message said:

You need a sharp tap and "real" cutting oil, *not* motor oil or
whatever.

What's the benefit to real cutting oil? How does "whatever" mess things up?

--
Phil, Squid-in-Training

Quoted message said:

From: "Phil, Squid-in-Training"

Quoted message said:

What's the benefit to real cutting oil? How does "whatever" mess things up?

Most of my threading experience is with steel and galvanized steel pipe
(tapered male thread), using muscle and motor power, for plumbing new
work/repair. I was a GE production welder for a shorter time, where we did some
(female) threading in steel and stainless steel enclosures. For stainless, they
had us use "Tap Magic". Rigid dark for steel. Some threading operations in the
plant, they also used Rigid dark. The Tap Magic used in mild steel seemed to
lead to broken/dulled taps faster than with the Rigid oil.

If real cutting oil is not used, threads break off as they are being formed.
"Emergency" field use of motor oil or even mixing motor oil with thread cutting
oil produces lots more broken threads, probably doesn't do much for taps/dies,
either. Rigid dark oil seems (bigtime) to work the best, and it is different
(more lard content?) by look and smell from Black Swan and one or two other
brands available. --TP

Quoted message said:

Quoted message said:

It's also straightforward to fill in new metal and cut a
fresh clean thread in a steel frame but you'll necessarily
lose paint .

Phil said:

Obviously, your threaded steerer example is different, but why would one
lose paint on a BB shell from a braze-fill? Does the brazing material spill
over to the outside of the BB shell? Can it be brazed work-side-up so that
the brazing stuff goes down to the other side of the BB (also easily tapped,
no?)?

Because brazing is usually in the 1500 to 1800 degrees F
range (silver's about 1200 &up but silver doesn't 'puddle'
as well). The paint burns off the outside when the BB shell
gets to about 500 degrees. Or more exactly, where
temperatures over that are expected, one removes the paint
first.

In rare cases, such as repairing a seatstay bridge or a
shift boss on a new frame, I've used an asbestos wrapper and
a low temperature silver for minimal paint loss but to flow
brass in a few threads all around a BB shell is enough BTUs
to make any temperature mask unworkable.

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Quoted message said:

"peter.kidwell" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

A friend of mine has stripped threads on the adjustable cup side of his
English bottom bracket.
The advice I have given is to fit a Stronglight threadless BB but I have
no experience of these are they successful or is there any other answer

peter.kidwell said:

Some of my cycling buddies have said to use oversize cups, are these still
available.
The frame is a Woodrupp (Small English Builder) Renolds 531 and very nice
too.

Yes, plus 0.5mm oversize cups were once available for all
threads, but no longer.

http://www.yellowjersey.org/photosfromthepast/CA746AOS.JPG
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Quoted message said:

Quoted message said:

Quoted message said:

Phil, Squid-in-Training wrote:
Obviously, your threaded steerer example is different, but
why would one
lose paint on a BB shell from a braze-fill? Does the brazing
material spill
over to the outside of the BB shell? Can it be brazed
work-side-up so that
the brazing stuff goes down to the other side of the BB (also
easily tapped, no?)?

Quoted message said:

"Zog The Undeniable" <[email hidden]> wrote in message
news:4182109f.0@entanet...

Quoted message said:

I think playing the flame of a brazing torch on the BB shell
may ruin the fine finish ;-)

Jay Beattie said:

But this does bring up a good point. Since it is just thread
repair, maybe a liquid metal or some wonder-bondo product could
be used instead of brass. This probably would gum up the tap,
but what the heck, you would save your paint. I do not know if
there is anything on the market tough enough to take a lasting
thread, but wonder products seem to appear on a daily basis. --

Devcon has a product like that and I suppose it would be
worth a try where the damage is slight and the paint has
value. Anyone tried that?

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

Quoted message said:

Quoted message said:

You need a sharp tap and "real" cutting oil, *not* motor oil or
whatever.

Phil said:

What's the benefit to real cutting oil? How does "whatever" mess things up?

Good cutting oil for steel has lard and sulpher. For
aluminum and bronze, kerosene or a similar consistency
proprietary mixture. Machine oil doesn't leave a nice crisp
thread and actually causes faster tool wear.

typically:
http://www.westpenn.com/sheets/dkthrd.html

--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

In article <[email hidden]>,
"Phil, Squid-in-Training" <[email hidden]>

Quoted message said:

Quoted message said:

You need a sharp tap and "real" cutting oil, *not* motor oil or
whatever.

What's the benefit to real cutting oil? How does "whatever" mess things up?

Cutting oil takes heat out of the cut more quickly than motor oil
does, so the cutting edges stay sharp longer. Plain water is even
better--great for cooling, but [censored] for lubrication, so you'd likely
break taps all over the place if you tried to use it. Cutting oil is
right down the middle--good enough cooling and just enough lubrication.

--
B.B. --I am not a goat! thegoat4 at airmail.net

Quoted message said:

Cutting oil takes heat out of the cut more quickly than motor oil
does, so the cutting edges stay sharp longer. Plain water is even
better--great for cooling, but [censored] for lubrication, so you'd likely
break taps all over the place if you tried to use it. Cutting oil is
right down the middle--good enough cooling and just enough
lubrication.

Ahh... Thank you for the informative response. Does retapping threads cause
a lot of heat, though?

--
Phil, Squid-in-Training

A Muzi said:

Quoted message said:

"peter.kidwell" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

A friend of mine has stripped threads on the adjustable cup side
of his English bottom bracket.
The advice I have given is to fit a Stronglight threadless BB but I
have no experience of these are they successful or is there any
other answer

peter.kidwell said:

Some of my cycling buddies have said to use oversize cups, are these
still available.
The frame is a Woodrupp (Small English Builder) Renolds 531 and very
nice too.

Yes, plus 0.5mm oversize cups were once available for all
threads, but no longer.

http://www.yellowjersey.org/photosfromthepast/CA746AOS.JPG

I should know this, but the thread diameter are meausured from the OD of the
threads? Is it this way for all designations?
--
Phil, Squid-in-Training