I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

How is such made? I assume it's a combination of steel formulation and
post-manufacture heat treating; true?


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

David Lesher wrote:

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

http://en.wikipedia.org/wiki/Shape_memory_alloy

HTH,

Wes

On Fri, 28 Nov 2008 22:43:02 +0000 (UTC), David Lesher
wrote:

I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

Umm. The modulus of elasticity????? Is this multiple choice?

RWL

GeoLane at PTD dot NET wrote in message
...
On Fri, 28 Nov 2008 22:43:02 +0000 (UTC), David Lesher
wrote:

I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

Umm. The modulus of elasticity????? Is this multiple choice?

RWL

The modulus of elasticity for all grades of steel is about the same.
Stainless is slightly lower.

--
Ed Huntress

The modulous of elasticity for most grades of steel is the same
(29x10^6) What varies is the amount it can be bent before it takes a
permanent set in the new shape. So you are looking for a steel with
high yield strength.

I'd suggest heading to the local hobby shop or well stocked hardware
store, ask for 'music wire'. It comes in 36" lengths, can be bent to
take a shape, is about as springy as you can get without special alloys
or special heat treating. Make the shape you are looking for, see it the
music wire will do the job for you.

If so, your local wireform place can make them by the million very cheaply.

David Lesher wrote:
I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

How is such made? I assume it's a combination of steel formulation and
post-manufacture heat treating; true?

"David Lesher" wrote in message
...


I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

How is such made? I assume it's a combination of steel formulation and
post-manufacture heat treating; true?

The simple answer is that the amount it can be sprung is a function of its
yield strength.

Springs like you're describing fail in one of two ways: they exceed their
elastic limit, which is another way of saying yield strength, and then take
a permanent bend that doesn't fully recover. Or they break.

Yes, your assumptions about steel grade and heat treatment are correct. If
you're pushing your spring pretty hard, finding the right material and
treatment can be a real challenge. If you're well within the elastic limit
of ordinary carbon steel that's hard-drawn, such as music wire, you'll find
the task to be an easy one. And everything in between, etc.

Any spring should return to its original shape if you don't exceed that
limit. Some will break before you bend them far enough. Some will eventually
get weaker and lose some of their ability to spring back. How many millions
of cycles are you thinking of? And if not millions, what?

--
Ed Huntress

It's a ... lockpick torque.

Am I right?

"David Lesher" wrote in message
...


I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

How is such made? I assume it's a combination of steel formulation and
post-manufacture heat treating; true?


--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

"Tom Dacon" writes:

It's a ... lockpick torque.

Am I right?

No, such are available now.

--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

On Nov 28, 5:43*pm, David Lesher wrote:
I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

How is such made? I assume it's a combination of steel formulation and
post-manufacture heat treating; true?

You could experiment with Music Wire, or study Statics to learn the
mathematical principles of deformation. Music wire can be bent to
shape cold but not necessarily annealed and then heat-treated back to
the original condition. Spring tempering is a tricky art if you don't
have the right expensive equipment.

On Fri, 28 Nov 2008 22:04:59 -0500, GeoLane at PTD dot NET wrote:

On Fri, 28 Nov 2008 22:43:02 +0000 (UTC), David Lesher
wrote:

I'm envisioning a gadget I can see a use for....

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

What controls how much it can be bent without altering the final shape?

Umm. The modulus of elasticity????? Is this multiple choice?

RWL

As Ed mentioned the modulus of elasticity is pretty much the same for all
steels. What makes a difference to how far you can bend something before
it yields is the ratio of the modulus of elasticity and the yield
strength of the material.

Heat treatment and high carbons increase the yield strength, until
eventually the material snaps instead of permanently bending. But they
don't significantly change the modulus of elasticity.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

On Fri, 28 Nov 2008 19:26:52 -0500, Wes wrote:

David Lesher wrote:

It would be made from spring steel, say coat-hanger diameter, in s
specific shape. Key to its use would be it could be bent in one way to
deploy it, but it would revert to its original shape.

http://en.wikipedia.org/wiki/Shape_memory_alloy

HTH,

Wes

Y'know, I could envision some things (a basket-shaped stent, for
instance) that could be done just with the right temper of material. But
at some point, yes, you need shape memory alloy.

I want to get some sometime, just to play. Small parts carries shape
memory wire, and I think it's really cool that you can make a part at one
temperature, wad it up into a ball at another temperature, then cool it
down and have it spring out in the original shape.

--
Tim Wescott
Control systems and communications consulting
http://www.wescottdesign.com

Need to learn how to apply control theory in your embedded system?
"Applied Control Theory for Embedded Systems" by Tim Wescott
Elsevier/Newnes, http://www.wescottdesign.com/actfes/actfes.html

"Ed Huntress" writes:


The simple answer is that the amount it can be sprung is a function of its
yield strength.

Springs like you're describing fail in one of two ways: they exceed their
elastic limit, which is another way of saying yield strength, and then take
a permanent bend that doesn't fully recover. Or they break.

Ahh, thank you. I didn't think "yield strength" when bending up a coat hanger
in the shape I needed.

Any spring should return to its original shape if you don't exceed that
limit. Some will break before you bend them far enough. Some will eventually
get weaker and lose some of their ability to spring back. How many millions
of cycles are you thinking of? And if not millions, what?

Dozens, I guess. It would be a seldom-used hand tool, to reach in and
"give a hand" somewhere no hand [save Thing, I guess..] could be.

But you'd have to bend it a different way to get it in there and out,
later. Hence my query original shape. Something with the flexibility
of a Slinky might do the job.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

"David Lesher" wrote in message
...
"Ed Huntress" writes:


The simple answer is that the amount it can be sprung is a function of its
yield strength.

Springs like you're describing fail in one of two ways: they exceed their
elastic limit, which is another way of saying yield strength, and then
take
a permanent bend that doesn't fully recover. Or they break.

Ahh, thank you. I didn't think "yield strength" when bending up a coat
hanger
in the shape I needed.

Any spring should return to its original shape if you don't exceed that
limit. Some will break before you bend them far enough. Some will
eventually
get weaker and lose some of their ability to spring back. How many
millions
of cycles are you thinking of? And if not millions, what?

Dozens, I guess. It would be a seldom-used hand tool, to reach in and
"give a hand" somewhere no hand [save Thing, I guess..] could be.

OK, so the long-term ability of the material to hold up is not an issue. You
can use practically any steel that has the required strength.


But you'd have to bend it a different way to get it in there and out,
later. Hence my query original shape. Something with the flexibility
of a Slinky might do the job.

I'm not visualizing this, but if you're saying you have to bend a round bar
one way and then the other way, the material will bend to the same degree
either way. If you're trying to trigger a return to a specific shape, you'll
note the references to shape-memory alloys. They're triggered by specific
temperatures, and they don't sound to me like what you're looking for.

Why don't you go down to your local hobby shop and buy a few pieces of music
wire, and try them out? It's a cheap way to see what you're dealing with.
You can bend it without breaking, but the material has pretty good spring
properties. Standard music wire is available in diameters up to 1/8". There
are some suppliers who make it in larger diameters but the larger the
diameter, the weaker the steel.

That's because it's very high-carbon steel that's work-hardened by drawing,
not by heat-treating. Strength of music wire is inversely related to its
diameter. But its strength is pretty high. It's a nice, simple material from
which to make medium-performance springs.

--
Ed Huntress

On Nov 29, 1:00*pm, David Lesher wrote:
...
Dozens, I guess. It would be a seldom-used hand tool, to reach in and
"give a hand" somewhere no hand [save Thing, I guess..] could be.

But you'd have to bend it a different way to get it in there and out,
later. Hence my query original shape. Something with the flexibility
of a Slinky might do the job.

Metals work-harden when bent or stretched beyond their elastic limit.
That's why you can bend but not completely straighten a paper clip
with your fingers. Each new bend will be in a different place. Coat-
hanger-sized music wire may be too difficult to bend accurately by
hand. Try gas welding rod, which is similar in initial strength to a
coat hanger but readily available in 3' lengths. You still won't be
able to bend and straighten it again very well, or more than a few
times. Soft black iron wire, like baling wire, might last longest. It
isn't nearly as stiff as the welding rod or a coathanger.

I just tried bending 1/16" welding rod and soft black iron wire 90
degrees and back in a vise. I'm not going to sacrifice an
irreplaceable old coathanger for you. The welding rod snapped off at
the 4th bend. The soft wire started to weaken at 10 and cracked at 16.
These were very sharp bends around the vise jaw. Your mileage (and the
properties of the particular batch of steel you buy) may vary.

jw

On Sat, 29 Nov 2008 18:00:48 +0000 (UTC), the infamous David Lesher
scrawled the following:

"Ed Huntress" writes:


The simple answer is that the amount it can be sprung is a function of its
yield strength.

Springs like you're describing fail in one of two ways: they exceed their
elastic limit, which is another way of saying yield strength, and then take
a permanent bend that doesn't fully recover. Or they break.

Ahh, thank you. I didn't think "yield strength" when bending up a coat hanger
in the shape I needed.

Any spring should return to its original shape if you don't exceed that
limit. Some will break before you bend them far enough. Some will eventually
get weaker and lose some of their ability to spring back. How many millions
of cycles are you thinking of? And if not millions, what?

Dozens, I guess. It would be a seldom-used hand tool, to reach in and
"give a hand" somewhere no hand [save Thing, I guess..] could be.

But you'd have to bend it a different way to get it in there and out,
later. Hence my query original shape. Something with the flexibility
of a Slinky might do the job.

I know what it is. You're reinventing the Slim Jim lockout tool,
aren't you? wink

http://en.wikipedia.org/wiki/Slim_Jim_(lock_pick)

--
In all affairs it's a healthy thing now and then to hang a
question mark on the things you have long taken for granted.
-- Bertrand Russell

Tim Wescott wrote:

I want to get some sometime, just to play. Small parts carries shape
memory wire, and I think it's really cool that you can make a part at one
temperature, wad it up into a ball at another temperature, then cool it
down and have it spring out in the original shape.


I can not find the small parts catalog atm. How pricey is that stuff?

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

www.smallparts.com

Look for Nitinol materials

Roger

"Wes" wrote in message
...
Tim Wescott wrote:

I want to get some sometime, just to play. Small parts carries shape
memory wire, and I think it's really cool that you can make a part at one
temperature, wad it up into a ball at another temperature, then cool it
down and have it spring out in the original shape.


I can not find the small parts catalog atm. How pricey is that stuff?

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

"Roger Jones" wrote:

Look for Nitinol materials

Cheap enough to play with. Thanks Roger and Tim.

Wes
--
"Additionally as a security officer, I carry a gun to protect
government officials but my life isn't worth protecting at home
in their eyes." Dick Anthony Heller

"Ed Huntress" writes:


Dozens, I guess. It would be a seldom-used hand tool, to reach in and
"give a hand" somewhere no hand [save Thing, I guess..] could be.

OK, so the long-term ability of the material to hold up is not an issue. You
can use practically any steel that has the required strength.

But you'd have to bend it a different way to get it in there and out,
later. Hence my query original shape. Something with the flexibility
of a Slinky might do the job.

I'm not visualizing this, but if you're saying you have to bend a round bar
one way and then the other way, the material will bend to the same degree
either way. If you're trying to trigger a return to a specific shape, you'll
note the references to shape-memory alloys.

No, I need it to be one shape, say, oh, a S-curve 2 inches wide, and 4
tall. But the access hole is ~0.75" dia. so you have to straighten it
to fit inside. Then it reverts to S. You do your magic. You pull it out
again, and it again is S shaped. You store it.

And no, this is no Slim-Jim. I own one somewhere, however.
--
A host is a host from coast to
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433

"David Lesher" wrote in message
...
"Ed Huntress" writes:


Dozens, I guess. It would be a seldom-used hand tool, to reach in and
"give a hand" somewhere no hand [save Thing, I guess..] could be.

OK, so the long-term ability of the material to hold up is not an issue.
You
can use practically any steel that has the required strength.

But you'd have to bend it a different way to get it in there and out,
later. Hence my query original shape. Something with the flexibility
of a Slinky might do the job.

I'm not visualizing this, but if you're saying you have to bend a round
bar
one way and then the other way, the material will bend to the same degree
either way. If you're trying to trigger a return to a specific shape,
you'll
note the references to shape-memory alloys.

No, I need it to be one shape, say, oh, a S-curve 2 inches wide, and 4
tall. But the access hole is ~0.75" dia. so you have to straighten it
to fit inside. Then it reverts to S. You do your magic. You pull it out
again, and it again is S shaped. You store it.

Oh, then that's either a shape-memory alloy, or something you hold into one
shape and then let it spring into another. For example, sliding the S-shaped
spring into a 5/8" tube to get it into the entry hole, and then sliding the
tube back out when the spring is inside.

--
Ed Huntress