How are nipple threads made?

jt said:

Spoke threads are rolled (usually).

Are nipple threads made with a forming tap?

Speaking from a machinist point of view, I'd say yes.

The form taps (also called roll taps) would probably cause a slight deformation of the outside
diameter (due to the relatively thin wall), so the milling of the wrench flats would be a later
operation and eliminate the "bulging". I would think that a form tap would be used for both Aluminum
and brass nipples. The brass tends to be "grabbier" and has a tendency to grab the small taps and
break them. But since nipples are probably made by the gazillion on a Swiss screw machine, and those
usually run in a oil flood, it shouldn't really be a problem especially once the process is
optimized.

The form taps are also stronger since there is no flute for chip removal and thus more body for
strength. However, they are more critical of tap hole diameter. You need an accurate size hole for
proper threading and thread strength. Accurate holes size is not a problem for Swiss screw machines.

As with roll forming the spokes threads, I'd would think the forming (as opposed to cutting) of
female threads in the nipples have a similar increase in strength.

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"jt" <[email hidden]> wrote in message
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Quoted message said:

Spoke threads are rolled (usually).

Are nipple threads made with a forming tap?

What's a "forming tap"?

Nipples are headed from brass , milled for the wrench flats*, threaded with our industry's odd
2x56tpi** tap, milled for the end slot, then tumble-plated.

I have a Torringon one with half of a tap still in it, and several other aberrant spokes and nipples
from a lifetime of handling them.

*or, for six sided format, cut from hex stock. **or the appropriate diameter if else.
--
Andrew Muzi yellowjersey.orgyellowjersey.orgOpen ↗ Open every day since 1 April 1971

I have not seen how they are made but I have seen spoke nipples that were forged to final shape
except for the screwdriver slot. Their wrench flats were formed in a die that gave a transition from
the round body that could not be created by machining. I suspect these also have had formed rather
than cut threads.

tinyurl.comewlzOpen ↗

In any case, "express" taps produce a stronger thread than cutting taps. Just the same I see many
machined spoke nipples.

Jobst Brandt [email hidden] Palo Alto CA

I have not seen how they are made but I have seen spoke nipples that were forged to final shape
except for the screwdriver slot. Their wrench flats were formed in a die that gave a transition from
the round body that could not be created by machining. I suspect these also have had formed rather
than cut threads.

besly.comstdtaps.htmOpen ↗ tinyurl.comewlzOpen ↗

In any case, "X-press" taps produce a stronger thread than cutting taps. Just the same I see many
machined spoke nipples.

Jobst Brandt [email hidden] Palo Alto CA

A Muzi said:

What's a "forming tap"?

A form or roll tap as they are known (not express, which I believe is a trade name) does not cut
female threads. They "mash" them into shape. Not that different than rolling the male threads on
spokes. The forming/rolling/mashing... keeps the grain structure of the material "flowing". If you
were to cut the threads the grain gets interupted and a loss of strength is the result.

Take a look at the links that Jobst posted. They show what a form tap looks like. Pretty much looks
like a regular tap except there is no cutting edge or flute (for chip evacuation).

FWIW, larger form taps (some 1/4", most 5/16 and up) have a very narrow flute on one side. I don't
know what it's for since it's too small for chips. It maybe a place to trap some cutting oils.

Quoted message said:

Nipples are headed from brass , milled for the wrench flats*, threaded with our industry's odd
2x56tpi**

2-56 taps are not odd, unusual, rare or otherwise different. I've been cutting (or forming) that
thread for 20 years. It may be strange in the bike industry only because most things are metric
threaded. Except of course for pedals, BB... I guess there have been too many "standards" in the
bike industry and now there is just a mish-mash bastardization of standards for a bike.

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Quoted message said:

I have not seen how they are made but I have seen spoke nipples that were forged to final shape
except for the screwdriver slot. Their wrench flats were formed in a die that gave a transition
from the round body that could not be created by machining.

Hmmm? A progressive die would be a good, fast way to make strong nipples. When did you see this?? A
modern Swiss screw machine with a "live" head(s) could mill the flats, saw the screwdriver slot,
drill and tap pretty darn quickly. Might be a toss-up for speed, but the die method may be stronger.
Cold forging if you will. Then again, the die method may require a second setup and machine which
would then require human handling and increase time and costs.

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Skuke who? said:

Quoted message said:

I have not seen how they are made but I have seen spoke nipples that were forged to final shape
except for the screwdriver slot. Their wrench flats were formed in a die that gave a transition
from the round body that could not be created by machining.

Quoted message said:

Hmmm? A progressive die would be a good, fast way to make strong nipples. When did you see this??
A modern Swiss screw machine with a "live" head(s) could mill the flats, saw the screwdriver slot,
drill and tap pretty darn quickly. Might be a toss-up for speed, but the die method may be
stronger. Cold forging if you will. Then again, the die method may require a second setup and
machine which would then require human handling and increase time and costs.

All the spoke nipples (DT) I use at the present time are cold formed and I am fairly certain that
the thread is also formed, not cut although the thread shows brass while the nipple is plated. I
think the blanks are formed and plated then drilled, form threaded, and slotted by screw machines.

Jobst Brandt [email hidden] Palo Alto CA

Quoted message said:

Skuke who? writes:

Lywalker of course! :-)

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Quoted message said:

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

Quoted message said:

Spoke threads are rolled (usually).

Are nipple threads made with a forming tap?

I have a nipple that came from the factory with a normal fluted cutting tap broken off in it.

In the same box I also got a few nipples that had no center hole and a few with a center hole, but
no threads. I assume the latter came thru the threading maching before anyone noticed that the tap
was broken.

-
-----------------------------------------------
Jim Adney [email hidden] Madison, WI 53711 USA
-----------------------------------------------

Quoted message said:

A Muzi said:

What's a "forming tap"?

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

Quoted message said:

A form or roll tap as they are known (not express, which I believe is a trade name) does not cut
female threads. They "mash" them into shape.

Not

Quoted message said:

that different than rolling the male threads on spokes. The forming/rolling/mashing... keeps the
grain structure of the material "flowing". If you were to cut the threads the grain gets
interupted and a loss of strength is the result.

Take a look at the links that Jobst posted. They show what a form tap looks like. Pretty much
looks like a regular tap except there is no cutting edge or flute (for chip evacuation).

FWIW, larger form taps (some 1/4", most 5/16 and up) have a very narrow flute on one side. I don't
know what it's for since it's too small for chips. It maybe a place to trap some cutting oils.

Quoted message said:

Nipples are headed from brass , milled for the wrench flats*, threaded

with

Quoted message said:

Quoted message said:

our industry's odd 2x56tpi**

2-56 taps are not odd, unusual, rare or otherwise different. I've been cutting (or forming) that
thread for 20 years. It may be strange in the bike industry only because most things are metric
threaded. Except of course for pedals, BB... I guess there have been too many "standards" in the
bike industry and now there is just a mish-mash bastardization of standards for a bike.

I knew these as "rolling taps".. Hadn't heard "forming" before. Thanks.

--
Andrew Muzi yellowjersey.orgyellowjersey.orgOpen ↗ Open every day since 1 April 1971

skuke said:

A Muzi said:

Nipples are headed from brass , milled for the wrench flats*, threaded with our industry's odd
2x56tpi**

2-56 taps are not odd, unusual, rare or otherwise different. I've been cutting (or forming) that
thread for 20 years. It may be strange in the bike industry only because most things are metric
threaded.

Well if you had been a cycle-centric machinist during your tenure, you might have noticed that
spokes are not threaded #2-56, but rather 2mm-56tpi, which *is* a strange [censored] thread; Mr. Muzi
is right about that. #2-56 thread is close, in that a #2-56 nut will spin on to a 14ga spoke
thread, but the fit is too loose and a nipple would be prone to thread failure if it were tapped
with that thread.

True to form, 15ga spokes are threaded 1.8mm-56tpi.

It's analogous to some of the threads of the Italian standard which mix a metric diameter with an
inch pitch, e.g. 10mm-26tpi axles in Campy hubs. Italian BBs are what, 36mm-24tpi? It defies
understanding unless you assume that Italian industry were getting their thread cutting equipment
from Old Blighty.

Chalo Colina

Chalo said:

skuke said:

A Muzi said:

Nipples are headed from brass , milled for the wrench flats*, threaded with our industry's odd
2x56tpi**

2-56 taps are not odd, unusual, rare or otherwise different. I've been cutting (or forming) that
thread for 20 years. It may be strange in the bike industry only because most things are metric
threaded.

Well if you had been a cycle-centric machinist during your tenure, you might have noticed that
spokes are not threaded #2-56, but rather 2mm-56tpi, which *is* a strange [censored] thread; Mr. Muzi
is right about that. #2-56 thread is close, in that a #2-56 nut will spin on to a 14ga spoke
thread, but the fit is too loose and a nipple would be prone to thread failure if it were tapped
with that thread.

True to form, 15ga spokes are threaded 1.8mm-56tpi.

It's analogous to some of the threads of the Italian standard which mix a metric diameter with an
inch pitch, e.g. 10mm-26tpi axles in Campy hubs. Italian BBs are what, 36mm-24tpi? It defies
understanding unless you assume that Italian industry were getting their thread cutting equipment
from Old Blighty.

Chalo Colina

Thanks! I learned something new today.

Yes, I misread/understood Mr. Muzi's statement to be #2-56tpi and not 2mm-56tpi.

How on Earth did the bike industry wind up with that bastardization of a thread "standard"??

BTW, I do consider myself to be a cycling-centric machinist. I've made many custom component for
myself and others. I have not had the need (obviously) to thread either nipples or spokes. I try not
to make things that are easily (and more cheaply) purchased at the LBS.

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Quoted message said:

I have not seen how they are made but I have seen spoke nipples that were forges to final shape
except for the screwdriver slot.

Most spokes besides DT come furnished with nipples that are clearly swaged to form the square
section. There is a telltale pillowy characteristic to the flats on these nipples, and I find that
their somewhat rounded faces are more vulnerable to further rounding than are the machined type.

Chalo Colina

skuke said:

How on Earth did the bike industry wind up with that bastardization of a thread "standard"??

Hey, the bike industry is the HOME of bastardized "standards" (that aren't). As soon as it can be
conclusively determined that something works, it MUST be changed.

Mark Hickey Habanero Cycles habcycles.comhabcycles.comOpen ↗ Home of the $695 ti frame

skuke said:

BTW, I do consider myself to be a cycling-centric machinist. I've made many custom component for
myself and others. I have not had the need (obviously) to thread either nipples or spokes. I try
not to make things that are easily (and more cheaply) purchased at the LBS.

Amen to that.

After building a bike for which I machined the hubs, front brakes, fork crown and steerer, stem,
seatpost, bottom bracket, chainring spider and guards, and pump, I resolved to make do thereafter
with commercially available components when they will do the job. Though commodity parts have fewer
bragging rights attached, they are much cheaper in the big picture-- and easily replaceable.

Chalo Colina

Mark Hickey said:

Hey, the bike industry is the HOME of bastardized "standards" (that aren't). As soon as it can be
conclusively determined that something works, it MUST be changed.

If you think the bicycle industry is the premier exhibitor of that effect, you've never
worked in IT.

Jasper