How can I blacken stainless steel spokes?

someone wrote:
On 21 May, 04:52, jim beam wrote:

Stop flailing. �That's not a measurement of magnetic attraction. �A
magnet does not quantify the attraction.
rubbish. �if you want absolutes, you can calibrate the "strength" of the
magnet, and go from there. �but you don't need absolutes, you need
relatives. �and for that, you will have to empirically plot data. �the
only variable will be degree of martensitic transformation.

relatives are god. how do I get datas from a magnet? I want a pass/
fail tool.


you're not going to get one. partly because the degree of
transformation doesn't tell you anything unless you plot it relative to
failure of your specific system. [pick the exact alloy, and the exact
component, then plot percentage magnetic attraction against strain until
failure. then average over a number of repeated tests.] and because
martensites can be extremely strong [maraging steels].

time to dig out your instron.

"someone" wrote in message
...
On 21 May, 04:52, jim beam wrote:

Stop flailing. That's not a measurement of magnetic attraction. A
magnet does not quantify the attraction.

rubbish. if you want absolutes, you can calibrate the "strength" of the
magnet, and go from there. but you don't need absolutes, you need
relatives. and for that, you will have to empirically plot data. the
only variable will be degree of martensitic transformation.

relatives are god. how do I get datas from a magnet? I want a pass/
fail tool.

end of original posts
someone,
From your previous post I thought that you wanted to quantify the magnetic
attraction, which I interpreted as wanting to know its value for each
increment of spoke length. This post sounds like you want only a pass/fail,
which doesn't seem like the same thing. (the first is quantitative analysis,
the second is qualitative or categorical analysis).
To do quantitative analysis, which gives more information, you might attach
a magnet to a horizontally mounted force gauge (gauge axis perpendicular to
the spoke axis) and scan this assembly along the length of the spoke at a
constant distance, recording the force due to magnetic attraction at
suitable intervals. Don't know how this would work at the bent end of the
spoke - maybe if the spoke head was oriented vertically.
Kerry

On 21 May, 06:15, "Kerry Montgomery" wrote:
"someone" wrote in message

...
On 21 May, 04:52, jim beam wrote:

Stop flailing. That's not a measurement of magnetic attraction. A
magnet does not quantify the attraction.

rubbish. if you want absolutes, you can calibrate the "strength" of the
magnet, and go from there. but you don't need absolutes, you need
relatives. and for that, you will have to empirically plot data. the
only variable will be degree of martensitic transformation.

relatives are god. *how do I get datas from a magnet? *I want a pass/
fail tool.

end of original posts
someone,
From your previous post I thought that you wanted to quantify the magnetic
attraction, which I interpreted as wanting to know its value for each
increment of spoke length. This post sounds like you want only a pass/fail,
which doesn't seem like the same thing. (the first is quantitative analysis,
the second is qualitative or categorical analysis).
To do quantitative analysis, which gives more information, you might attach
a magnet to a horizontally mounted force gauge (gauge axis perpendicular to
the spoke axis) and scan this assembly along the length of the spoke at a
constant distance, recording the force due to magnetic attraction at
suitable intervals. Don't know how this would work at the bent end of the
spoke - maybe if the spoke head was oriented vertically.
Kerry

I was thinking of placing a magnet on electronic scales and passing
the spoke over the magnet, noting the reduction in downward force.
Either end would be difficult to receive accurate results. The magnet
would have to be very small and the balance sensitive.

someone wrote:
On 21 May, 06:15, "Kerry Montgomery" wrote:
"someone" wrote in message

...
On 21 May, 04:52, jim beam wrote:

Stop flailing. That's not a measurement of magnetic attraction. A
magnet does not quantify the attraction.
rubbish. if you want absolutes, you can calibrate the "strength" of the
magnet, and go from there. but you don't need absolutes, you need
relatives. and for that, you will have to empirically plot data. the
only variable will be degree of martensitic transformation.
relatives are god. �how do I get datas from a magnet? �I want a pass/
fail tool.

end of original posts
someone,
From your previous post I thought that you wanted to quantify the magnetic
attraction, which I interpreted as wanting to know its value for each
increment of spoke length. This post sounds like you want only a pass/fail,
which doesn't seem like the same thing. (the first is quantitative analysis,
the second is qualitative or categorical analysis).
To do quantitative analysis, which gives more information, you might attach
a magnet to a horizontally mounted force gauge (gauge axis perpendicular to
the spoke axis) and scan this assembly along the length of the spoke at a
constant distance, recording the force due to magnetic attraction at
suitable intervals. Don't know how this would work at the bent end of the
spoke - maybe if the spoke head was oriented vertically.
Kerry

I was thinking of placing a magnet on electronic scales and passing
the spoke over the magnet, noting the reduction in downward force.
Either end would be difficult to receive accurate results. The magnet
would have to be very small and the balance sensitive.

that should work. but how are you going to determine degree of
martensite transition?

On 22 May, 04:14, jim beam wrote:
someone wrote:
On 21 May, 06:15, "Kerry Montgomery" wrote:
"someone" wrote in message

....
On 21 May, 04:52, jim beam wrote:

Stop flailing. That's not a measurement of magnetic attraction. A
magnet does not quantify the attraction.
rubbish. if you want absolutes, you can calibrate the "strength" of the
magnet, and go from there. but you don't need absolutes, you need
relatives. and for that, you will have to empirically plot data. the
only variable will be degree of martensitic transformation.
relatives are god. how do I get datas from a magnet? I want a pass/
fail tool.

end of original posts
someone,
From your previous post I thought that you wanted to quantify the magnetic
attraction, which I interpreted as wanting to know its value for each
increment of spoke length. This post sounds like you want only a pass/fail,
which doesn't seem like the same thing. (the first is quantitative analysis,
the second is qualitative or categorical analysis).
To do quantitative analysis, which gives more information, you might attach
a magnet to a horizontally mounted force gauge (gauge axis perpendicular to
the spoke axis) and scan this assembly along the length of the spoke at a
constant distance, recording the force due to magnetic attraction at
suitable intervals. Don't know how this would work at the bent end of the
spoke - maybe if the spoke head was oriented vertically.
Kerry

I was thinking of placing a magnet on electronic scales and passing
the spoke over the magnet, noting the reduction in downward force.
Either end would be difficult to receive accurate results. *The magnet
would have to be very small and the balance sensitive.

that should work. *but how are you going to determine degree of
martensite transition?

I was only hoping for an indication. To be able to 'see' what cant be
seen with the eye. A comparison showing equal magnetic response to a
spoke from a known poor batch (early failure) would I feel to be
sufficient to be able to confidently reject the current batch under
suspicion based on one sample.

someone wrote:
On 22 May, 04:14, jim beam wrote:
someone wrote:
On 21 May, 06:15, "Kerry Montgomery" wrote:
"someone" wrote in message
...
On 21 May, 04:52, jim beam wrote:
Stop flailing. That's not a measurement of magnetic attraction. A
magnet does not quantify the attraction.
rubbish. if you want absolutes, you can calibrate the "strength" of the
magnet, and go from there. but you don't need absolutes, you need
relatives. and for that, you will have to empirically plot data. the
only variable will be degree of martensitic transformation.
relatives are god. how do I get datas from a magnet? I want a pass/
fail tool.
end of original posts
someone,
From your previous post I thought that you wanted to quantify the magnetic
attraction, which I interpreted as wanting to know its value for each
increment of spoke length. This post sounds like you want only a pass/fail,
which doesn't seem like the same thing. (the first is quantitative analysis,
the second is qualitative or categorical analysis).
To do quantitative analysis, which gives more information, you might attach
a magnet to a horizontally mounted force gauge (gauge axis perpendicular to
the spoke axis) and scan this assembly along the length of the spoke at a
constant distance, recording the force due to magnetic attraction at
suitable intervals. Don't know how this would work at the bent end of the
spoke - maybe if the spoke head was oriented vertically.
Kerry
I was thinking of placing a magnet on electronic scales and passing
the spoke over the magnet, noting the reduction in downward force.
Either end would be difficult to receive accurate results. �The magnet
would have to be very small and the balance sensitive.
that should work. �but how are you going to determine degree of
martensite transition?

I was only hoping for an indication. To be able to 'see' what cant be
seen with the eye. A comparison showing equal magnetic response to a
spoke from a known poor batch (early failure) would I feel to be
sufficient to be able to confidently reject the current batch under
suspicion based on one sample.

i think you're still laboring under a massive misconception if you think
magnetism is going to give you any indication of performance in fatigue.
simply buy your spokes from a reputable manufacturer, make sure you
bed the spokes into the hub properly, build with even spoke tension per
rim manufacturer spec, and forget it.

On 22 May, 05:09, jim beam wrote:
someone wrote:
On 22 May, 04:14, jim beam wrote:
someone wrote:
On 21 May, 06:15, "Kerry Montgomery" wrote:
"someone" wrote in message
...
On 21 May, 04:52, jim beam wrote:
Stop flailing. That's not a measurement of magnetic attraction. A
magnet does not quantify the attraction.
rubbish. if you want absolutes, you can calibrate the "strength" of the
magnet, and go from there. but you don't need absolutes, you need
relatives. and for that, you will have to empirically plot data. the
only variable will be degree of martensitic transformation.
relatives are god. how do I get datas from a magnet? I want a pass/
fail tool.
end of original posts
someone,
From your previous post I thought that you wanted to quantify the magnetic
attraction, which I interpreted as wanting to know its value for each
increment of spoke length. This post sounds like you want only a pass/fail,
which doesn't seem like the same thing. (the first is quantitative analysis,
the second is qualitative or categorical analysis).
To do quantitative analysis, which gives more information, you might attach
a magnet to a horizontally mounted force gauge (gauge axis perpendicular to
the spoke axis) and scan this assembly along the length of the spoke at a
constant distance, recording the force due to magnetic attraction at
suitable intervals. Don't know how this would work at the bent end of the
spoke - maybe if the spoke head was oriented vertically.
Kerry
I was thinking of placing a magnet on electronic scales and passing
the spoke over the magnet, noting the reduction in downward force.
Either end would be difficult to receive accurate results. The magnet
would have to be very small and the balance sensitive.
that should work. but how are you going to determine degree of
martensite transition?

I was only hoping for an indication. *To be able to 'see' what cant be
seen with the eye. *A comparison showing equal magnetic response to a
spoke from a known poor batch (early failure) would I feel to be
sufficient to be able to confidently reject *the current batch under
suspicion based on one sample.

i think you're still laboring under a massive misconception if you think
magnetism is going to give you any indication of performance in fatigue.
* simply buy your spokes from a reputable manufacturer, make sure you
bed the spokes into the hub properly, build with even spoke tension per
rim manufacturer spec, and forget it.

gravity and magnetism are magic. I'll use magic if it will help.

On May 12, 1:18*pm, Johan Bornman wrote:
Nowadays with all the spoke options I am hard-pressed to keep, or
indeed, find stock of all the permutations. How do they blacken spokes
and can this be done in a workshop as and when needed?

Dear Johan,

An email asked me about testing for magnetic change due to spoke
threading, which is apparently being discussed somewhere in this
sprawling thread. Your initial post had nothing to do with magnetism,
but it's a handy place to hang this post.

Does rolling the threads into a stainless steel spoke have a
significant effect on the magnetic properties of the metal?

Short answer, not apparently.

Testing is fairly simple, if you have a cheap electronic scale that
reads in tenths of a gram, some hard drive magnets, a straight
stainless steel spoke to sacrifice, and a pair of cutting pliers.

First, cut off the spoke elbow.

Now you have a straight rod that weighs 7.2 grams, with a threaded and
an unthreaded end:

http://i43.tinypic.com/259zz1f.jpg

Lay the clipped spoke on the scale with one end aligned above two
pieces of non-magnetic inner tube, slap a pair of hard drive magnets
on a stand, and fiddle them closer and closer to the end of the spoke
until the scale registers the faint pull.

Clink!

At about 6.0 grams, the spoke starts to tilt up a tiny bit, gets too
close to the magnet, and leaps up, ruining everything.

So raise the magnets just a little higher . . .

There! The two hard drive magnets pull the spoke-end up enough to
lower the weight on the scale without the spoke-end jumping up. Here's
a low-angle view of the setup:

http://i40.tinypic.com/1418acj.jpg

(The threaded end is on the right. The end under the magnets is just
darker, due to lighting.)

Test each end of the spoke several times, leaving the scale and the
magnets untouched, and aligning the end of the spoke with the two
pieces of non-magnetic inner tube.

The more magnetic the end of the spoke, the harder it will be pulled
upward, and the lower the reading on the scale.

Here the clipped end lowers the reading to 6.4 grams:
http://i40.tinypic.com/k55tg8.jpg

Here the clipped end lowers the reading to 6.5 grams on another trial:
http://i43.tinypic.com/w1e5c4.jpg

Yikes! The threaded end lowers the reading to only 6.6 grams, a weaker
pull:
http://i44.tinypic.com/2mynlms.jpg

Those three photos show how both spoke-ends repeatedly changed the
scale to anywhere from 6.4 to 6.6 grams. That seems to be the margin
of error, not any difference between the ends.

Sometimes the scale showed a little more than 6.5 grams, sometimes a
little less, but there was no consistent winner--sometimes the clipped
end was lighter, sometimes the threaded end was lighter.

More careful alignment on the scale and better equipment might tease
out a clear difference, but it would still be awfully small.

Heck, the slight raising of the rolled threads might put enough metal
closer to the magnet to account for the extra attraction.

Cheers,

Carl Fogel

wrote:
On May 12, 1:18�pm, Johan Bornman wrote:
Nowadays with all the spoke options I am hard-pressed to keep, or
indeed, find stock of all the permutations. How do they blacken spokes
and can this be done in a workshop as and when needed?

Dear Johan,

An email asked me about testing for magnetic change due to spoke
threading, which is apparently being discussed somewhere in this
sprawling thread. Your initial post had nothing to do with magnetism,
but it's a handy place to hang this post.

Does rolling the threads into a stainless steel spoke have a
significant effect on the magnetic properties of the metal?

Short answer, not apparently.

Testing is fairly simple, if you have a cheap electronic scale that
reads in tenths of a gram, some hard drive magnets, a straight
stainless steel spoke to sacrifice, and a pair of cutting pliers.

First, cut off the spoke elbow.

Now you have a straight rod that weighs 7.2 grams, with a threaded and
an unthreaded end:

http://i43.tinypic.com/259zz1f.jpg

Lay the clipped spoke on the scale with one end aligned above two
pieces of non-magnetic inner tube, slap a pair of hard drive magnets
on a stand, and fiddle them closer and closer to the end of the spoke
until the scale registers the faint pull.

Clink!

At about 6.0 grams, the spoke starts to tilt up a tiny bit, gets too
close to the magnet, and leaps up, ruining everything.

So raise the magnets just a little higher . . .

There! The two hard drive magnets pull the spoke-end up enough to
lower the weight on the scale without the spoke-end jumping up. Here's
a low-angle view of the setup:

http://i40.tinypic.com/1418acj.jpg

(The threaded end is on the right. The end under the magnets is just
darker, due to lighting.)

Test each end of the spoke several times, leaving the scale and the
magnets untouched, and aligning the end of the spoke with the two
pieces of non-magnetic inner tube.

The more magnetic the end of the spoke, the harder it will be pulled
upward, and the lower the reading on the scale.

Here the clipped end lowers the reading to 6.4 grams:
http://i40.tinypic.com/k55tg8.jpg

Here the clipped end lowers the reading to 6.5 grams on another trial:
http://i43.tinypic.com/w1e5c4.jpg

Yikes! The threaded end lowers the reading to only 6.6 grams, a weaker
pull:
http://i44.tinypic.com/2mynlms.jpg

Those three photos show how both spoke-ends repeatedly changed the
scale to anywhere from 6.4 to 6.6 grams. That seems to be the margin
of error, not any difference between the ends.

Sometimes the scale showed a little more than 6.5 grams, sometimes a
little less, but there was no consistent winner--sometimes the clipped
end was lighter, sometimes the threaded end was lighter.

More careful alignment on the scale and better equipment might tease
out a clear difference, but it would still be awfully small.

Heck, the slight raising of the rolled threads might put enough metal
closer to the magnet to account for the extra attraction.

Cheers,

Carl Fogel


1. because of complete inconsistency of fulcrum effects, you're better
off using an experimental layout like this:

http://www.exo.net/~pauld/activities...enmagnets.html

instead of having a magnet on a stick, simply use the spoke. try to
keep the spoke above exactly the same point on the magnet throughout.

2. the act of clipping, unless you're using a laser cutter or something
like that, deforms the metal, thus creating a martensitically
transformed, and thus magnetic, region.

On 23 May, 17:16, Still Just Me
wrote:
On Thu, 21 May 2009 21:31:06 -0700 (PDT), someone

wrote:
gravity and magnetism are magic. *I'll use magic if it will help.

Reasons for those forces are unknown, all we have are theories on how
they work. So, magic, God, take your pick - just be sure to pre-stress
your spokes so that the spoke God won't be offended.

Back to CERN now to spend a few billion more to collide some particles
that were never supposed to collide here on Earth and see if the magic
wears off.

What gave you the idea there's a spoke god?