Hi all,

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to 100
degrees F (38 C).

Right now, I'm contemplating a monstrosity full of pulleys and motors,
to apply several coats of polyurethane liquid with intervening drying
stages.

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl insulated
mild steel wire. At only 249 feet per roll, I am concerned about the
need for splices, though.

How would you approach this particular challenge?

Thanks!

--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.

Winston wrote:
....
How would you approach this particular challenge?

Magnet wire. E.g., from a MOT. Bob

Bob Engelhardt wrote:
Winston wrote:
...
How would you approach this particular challenge?

Magnet wire. E.g., from a MOT. Bob

I've got the current - carrying wire handled.
That'll be enamel - insulated copper, equivalent
to the magnet wire you mention. The challenge
is in sourcing some insulated iron or mild steel
that can be easily formed into a core for the
magnetic (not electrical) circuit.


Thanks!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

On Wed, 07 Oct 2009 14:01:03 -0700, Winston wrote:
Bob Engelhardt wrote:
Winston wrote:
...
How would you approach this particular challenge?

Magnet wire. E.g., from a MOT. Bob

I've got the current - carrying wire handled. That'll be enamel -
insulated copper, equivalent to the magnet wire you mention. The
challenge is in sourcing some insulated iron or mild steel that can be
easily formed into a core for the magnetic (not electrical) circuit.

Have you looked at painted/enameled clothes hanger wire?

Have Fun!
Rich

On Oct 7, 4:37*pm, Winston wrote:
Hi all,

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to 100
degrees F (38 C).

Right now, I'm contemplating a monstrosity full of pulleys and motors,
to apply several coats of polyurethane liquid with intervening drying
stages.

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl insulated
mild steel wire. At only 249 feet per roll, I am concerned about the
need for splices, though.

How would you approach this particular challenge?

Thanks!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

Of no use, but interesting as all getout:

http://www.persiangig.com/pages/down...r_book_12e.pdf

or

http://naserhashemnia.persiangig.com...r_book_12e.pdf

ppgs 41-53


Dave

Rich Grise wrote:
On Wed, 07 Oct 2009 14:01:03 -0700, Winston wrote:
Bob Engelhardt wrote:
Winston wrote:
...
How would you approach this particular challenge?
Magnet wire. E.g., from a MOT. Bob
I've got the current - carrying wire handled. That'll be enamel -
insulated copper, equivalent to the magnet wire you mention. The
challenge is in sourcing some insulated iron or mild steel that can be
easily formed into a core for the magnetic (not electrical) circuit.

Have you looked at painted/enameled clothes hanger wire?

That's a little thick for my application. I hope to maximize the
amount of 'iron' in the circuit by using small diameter wire.

That does sound like a good way to prototype it quickly and
cheaply, though. If I can make it work with coat hangers, it
should be a cinch with MIG wire!

Thanks!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

XR650L_Dave wrote:

(...)

http://www.persiangig.com/pages/down...r_book_12e.pdf

or

http://naserhashemnia.persiangig.com...r_book_12e.pdf

Downloaded and saved. Very interesting indeed.
Thanks, Dave!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

On Wed, 7 Oct 2009 14:40:46 -0700 (PDT), XR650L_Dave
wrote:

On Oct 7, 4:37*pm, Winston wrote:
Hi all,

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to 100
degrees F (38 C).

Right now, I'm contemplating a monstrosity full of pulleys and motors,
to apply several coats of polyurethane liquid with intervening drying
stages.

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl insulated
mild steel wire. At only 249 feet per roll, I am concerned about the
need for splices, though.

How would you approach this particular challenge?

Thanks!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

Of no use, but interesting as all getout:

http://www.persiangig.com/pages/down...r_book_12e.pdf

I dont read Arabic very well. Is there a translation available?


or

http://naserhashemnia.persiangig.com...r_book_12e.pdf

ppgs 41-53


Dave

GUNNER'S PRAYER:
"God grant me the serenity to accept the people
that don't need to get shot, the courage to shoot
the people that need shooting and the wisdom to know the difference.
And if need be, the skill to get it done before I have to reload."


0

Transformer Iron cores depend on Iron with a Oxide surface (black). I
don't know if your
MIG wire is suitable for that treatment.

Bill K7NOM

Winston wrote:
Hi all,

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to 100
degrees F (38 C).

Right now, I'm contemplating a monstrosity full of pulleys and motors,
to apply several coats of polyurethane liquid with intervening drying
stages.

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl insulated
mild steel wire. At only 249 feet per roll, I am concerned about the
need for splices, though.

How would you approach this particular challenge?

Thanks!

--Winston

Winston wrote:

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage

How about a single pass using a UV curing coating?

What do you need to make that can't use a tapewound core?

Kevin Gallimore

Bill Janssen wrote:
Transformer Iron cores depend on Iron with a Oxide surface (black). I
don't know if your
MIG wire is suitable for that treatment.

The MIG wire is 97% iron so I'm hoping that will be sufficient.
I suppose the oxide surface acts as an electrical insulator to limit
eddy current flow between laminations. For the prototype, varnish
would take that role.

Thanks!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

axolotl wrote:
Winston wrote:

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage

How about a single pass using a UV curing coating?

I didn't see that in Mcmaster or Enco.
Is that something I can pick up easily & cheaply?
I DAGS on '"uv curing" coating' but didn't come up
with a retail outlet. Suggestions?

What do you need to make that can't use a tapewound core?

Envision a really long 'E' core.
I want a lot of flux concentrated between the center pole
piece and the two outer pole pieces. Figure ca 10" long
with a 1" diameter center pole.


Thanks!


--Winston



--

I'm still waiting for another sublime, transcendent flash of adequacy.

On Oct 7, 4:37Â*pm, Winston @ bigbrother wrote:

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to
make the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to
100 degrees F (38 C).

Right now, I'm contemplating a monstrosity full of pulleys and motors,
to apply several coats of polyurethane liquid with intervening drying
stages.

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl
insulated mild steel wire. At only 249 feet per roll, I am concerned
about the need for splices, though.

How would you approach this particular challenge?

Depends on what you are making -- relay, transformer, choke,
electromagnet, vibrators for friends and loved ones, etc. Also
on form factor. Which of the shapes in following is closest
to what you want? http://en.wikipedia.org/wiki/Magnetic_core

Most of those shapes are commercially available, some in
lower-conductivity silicon steel laminations like in most
commercial transformers, others in ferrites or powdered iron.

One light coating of polyurethane on your wire probably would
be good enough. Have you thought about hanging the wire
between two well-separated trees outdoors and painting it with
a roller? Didn't think so. But seriously, if you string
the wire back and forth 10 or 20 times between two headers 40'
apart, it would be quite fast to paint it all with a roller.

http://www.femm.info/wiki also may be of interest
re finite elements magnetic modeling.

--
jiw

James Waldby fired this volley in
:

One light coating of polyurethane on your wire probably would
be good enough. Have you thought about hanging the wire
between two well-separated trees outdoors and painting it with
a roller? Didn't think so. But seriously, if you string
the wire back and forth 10 or 20 times between two headers 40'
apart, it would be quite fast to paint it all with a roller.


It's a lot easier than that. The old Fordson spark coils of tractor
mythology/fame used "stove pipe wire" for the core.

The trick is to anneal the wire in a slightly oxidizing fire (basicall,
"blue" it). The oxide coating is not significantly conductive. And for
what it's worth, the more thoroughly annealed the wire is, the greater
the permability and the higher the saturation current of the transformer
will be. Of course, the alloy plays a great part in this, with high-
silicon steels being good in this respect.

LLoyd

Winston wrote:

I DAGS on '"uv curing" coating' but didn't come up
with a retail outlet.

I would probably call Master Bond.


Envision a really long 'E' core.
I want a lot of flux concentrated between the center pole
piece and the two outer pole pieces. Figure ca 10" long
with a 1" diameter center pole.

Wouldn't be easier to make it from tape? Higher density and your choice
of magnetic materials, from amorphous to grain oriented silicon.

Kevin Gallimore

On 2009-10-07, Gunner Asch wrote:
On Wed, 7 Oct 2009 14:40:46 -0700 (PDT), XR650L_Dave
wrote:

Of no use, but interesting as all getout:

http://www.persiangig.com/pages/down...r_book_12e.pdf

I dont read Arabic very well. Is there a translation available?

Check the second URL (quoted below). It gets you a PDF file in
English -- with the sole nuisance that there is an '&' in the file name,
which unix and linux need special command-line tricks to deal with.

http://naserhashemnia.persiangig.com...r_book_12e.pdf

956 total pages.

First publication 1925, last shown in the usual information is
1998 (12th edition).

Total file size is 5.8 MB.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

On 8 Oct 2009 01:04:50 GMT, "DoN. Nichols" wrote:

On 2009-10-07, Gunner Asch wrote:
On Wed, 7 Oct 2009 14:40:46 -0700 (PDT), XR650L_Dave
wrote:

Of no use, but interesting as all getout:

http://www.persiangig.com/pages/down...r_book_12e.pdf

I dont read Arabic very well. Is there a translation available?

Check the second URL (quoted below). It gets you a PDF file in
English -- with the sole nuisance that there is an '&' in the file name,
which unix and linux need special command-line tricks to deal with.

http://naserhashemnia.persiangig.com...r_book_12e.pdf

956 total pages.

First publication 1925, last shown in the usual information is
1998 (12th edition).

Total file size is 5.8 MB.

Enjoy,
DoN.


Thanks!

At one time I started teaching myself Arabic but lost interest before
long.

Gunner

GUNNER'S PRAYER:
"God grant me the serenity to accept the people
that don't need to get shot, the courage to shoot
the people that need shooting and the wisdom to know the difference.
And if need be, the skill to get it done before I have to reload."


0

On Wed, 07 Oct 2009 13:37:24 -0700, the infamous Winston
scrawled the following:

Hi all,

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to 100
degrees F (38 C).

Right now, I'm contemplating a monstrosity full of pulleys and motors,
to apply several coats of polyurethane liquid with intervening drying
stages.

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl insulated
mild steel wire. At only 249 feet per roll, I am concerned about the
need for splices, though.

How would you approach this particular challenge?

Buy from McM and splice, then cover the few (soldered) splices with
shrinkwrap. Trying to _evenly_ coat wire will haunt and taunt you to
your grave, Winnie.

--
For me, pragmatism is not enough. Nor is that fashionable word "consensus."

To me consensus seems to be the process of abandoning all beliefs,
principles, values and policies in search of something in which no one
believes, but to which no one objects; the process of avoiding the very
issues that have to be solved, merely because you cannot get agreement
on the way ahead. What great cause would have been fought and won under
the banner "I stand for consensus"?
--Margaret Thatcher (in a 1981 speech)

LJ sez: It's a good thing we have concensus on the case of Anthropogenic
Global Warming (kumbaya), isn't it?

On Wed, 07 Oct 2009 14:01:03 -0700, the infamous Winston
scrawled the following:

Bob Engelhardt wrote:
Winston wrote:
...
How would you approach this particular challenge?

Magnet wire. E.g., from a MOT. Bob

I've got the current - carrying wire handled.
That'll be enamel - insulated copper, equivalent
to the magnet wire you mention. The challenge
is in sourcing some insulated iron or mild steel
that can be easily formed into a core for the
magnetic (not electrical) circuit.

Why the hell aren't you using low-eddy xfmr core mat'l, Win?
You're just stirring, aren't you? Fess up!

--
For me, pragmatism is not enough. Nor is that fashionable word "consensus."

To me consensus seems to be the process of abandoning all beliefs,
principles, values and policies in search of something in which no one
believes, but to which no one objects; the process of avoiding the very
issues that have to be solved, merely because you cannot get agreement
on the way ahead. What great cause would have been fought and won under
the banner "I stand for consensus"?
--Margaret Thatcher (in a 1981 speech)

LJ sez: It's a good thing we have concensus on the case of Anthropogenic
Global Warming (kumbaya), isn't it?

James Waldby wrote:
On Oct 7, 4:37 pm, Winston @ bigbrother wrote:

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to
make the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to
100 degrees F (38 C).

Right now, I'm contemplating a monstrosity full of pulleys and motors,
to apply several coats of polyurethane liquid with intervening drying
stages.

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl
insulated mild steel wire. At only 249 feet per roll, I am concerned
about the need for splices, though.

How would you approach this particular challenge?

Depends on what you are making -- relay, transformer, choke,
electromagnet,

You guessed it! It's an electromagnet.

Which of the shapes in following is closest
to what you want? http://en.wikipedia.org/wiki/Magnetic_core

The 'ER' core is the closest.
Unfortunately I need all pole pieces to be about 4 times longer
than we see in the illustration.

Most of those shapes are commercially available, some in
lower-conductivity silicon steel laminations like in most
commercial transformers, others in ferrites or powdered iron.

Yup. My application is at 60 Hz so I don't really need
ferrites. That is fortunate because this requires a 'full
custom' treatment. The tooling charge would probably be
awe - inspiring.

One light coating of polyurethane on your wire probably would
be good enough. Have you thought about hanging the wire
between two well-separated trees outdoors and painting it with
a roller? Didn't think so.

Funny you should mention that! I used a very similar method
to coat the copper windings. They've been suspended in
the back yard drying for the last few days!

But seriously, if you string
the wire back and forth 10 or 20 times between two headers 40'
apart, it would be quite fast to paint it all with a roller.

Hmmm. Perhaps a tubular roller on both ends so that I can
coat the unexposed side as soon as most of it is dry.

Food for thought.


http://www.femm.info/wiki also may be of interest
re finite elements magnetic modeling.


Very cool! I will play with that.


Thanks, James!


--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.

Lloyd E. Sponenburgh wrote:

(...)

Interesting!

I shall DAGS 'stove pipe wire' ASAP.

Thanks, Lloyd!


--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

axolotl wrote:
Winston wrote:

I DAGS on '"uv curing" coating' but didn't come up
with a retail outlet.

I would probably call Master Bond.

OK. Thanks!

Envision a really long 'E' core.
I want a lot of flux concentrated between the center pole
piece and the two outer pole pieces. Figure ca 10" long
with a 1" diameter center pole.

Wouldn't be easier to make it from tape? Higher density and your choice
of magnetic materials, from amorphous to grain oriented silicon.

Kevin Gallimore

I will DAGS on this concept ASAP.
I was completely unaware that the ferromagnetic material was
available in tape form.

Thanks, Kevin!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

Larry Jaques wrote:

(...)

Buy from McM and splice, then cover the few (soldered) splices with
shrinkwrap. Trying to _evenly_ coat wire will haunt and taunt you to
your grave, Winnie.

Hokay, Larry.

I gotta say Kevin's statement about the availability of ferromagnetic
material in tape form has me all a-twitter.

Perhaps this'll be much easier than I had first thought!

Thanks!

--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.

Larry Jaques wrote:

(...)

Why the hell aren't you using low-eddy xfmr core mat'l, Win?
You're just stirring, aren't you? Fess up!

Nuh UH!

Till a couple minutes ago, I wasn't even aware that one
could buy the material in tape format.
I'm trapped between chagrin, happiness and excitement!



--Win


--

I'm still waiting for another sublime, transcendent flash of adequacy.

On Wed, 07 Oct 2009 20:33:58 -0700, the infamous Winston
scrawled the following:

Larry Jaques wrote:

(...)

Buy from McM and splice, then cover the few (soldered) splices with
shrinkwrap. Trying to _evenly_ coat wire will haunt and taunt you to
your grave, Winnie.

Hokay, Larry.

I gotta say Kevin's statement about the availability of ferromagnetic
material in tape form has me all a-twitter.

Yeah, that's cool news. Show us links you find to be interesting,
wot?


Perhaps this'll be much easier than I had first thought!

Likely so. G'luck, and remember to GIF at 11.

--
Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)
--

On Wed, 07 Oct 2009 20:44:52 -0700, the infamous Winston
scrawled the following:

Larry Jaques wrote:

(...)

Why the hell aren't you using low-eddy xfmr core mat'l, Win?
You're just stirring, aren't you? Fess up!

Nuh UH!

Till a couple minutes ago, I wasn't even aware that one
could buy the material in tape format.
I'm trapped between chagrin, happiness and excitement!

Sure beats being trapped between Barack and a hard place, don't it?

--
Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)
--

Larry Jaques wrote:

(...)

Yeah, that's cool news. Show us links you find to be interesting,
wot?

Yassir. So far, these look very promising.
I don't see their online store, though.

https://www.arnoldmagnetics.com/mtc/index.htm
https://www.arnoldmagnetics.com/mtc/manuals.htm
https://www.arnoldmagnetics.com/prod...lled/index.htm
https://www.arnoldmagnetics.com/mtc/...des_081017.pdf

http://www.arnoldmagnetics.com/mtc/p...plicati on%22

(...)

Likely so. G'luck, and remember to GIF at 11.

Gotcha Chief.

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

On Oct 7, 5:51*pm, Winston wrote:
Bill Janssen wrote:
Transformer Iron cores depend on Iron with a Oxide surface (black). I
don't know if your
MIG wire is suitable for that treatment.

The MIG wire is 97% iron so I'm hoping that will be sufficient.
I suppose the oxide surface acts as an electrical insulator to limit
eddy current flow between laminations. *For the prototype, varnish
would take that role.

Thanks!

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

And steel is 99.9-99% iron. It's the little details that will get
you. My old, OLD electrical how-to from the teens and twenties shows
them using iron, not steel, wire for solenoid cores. The reason being
is that soft iron, not steel, wire will have little or no remaining
field once the current is turned off. You want it magnetized only
when the current is on. And eddy currents are only there if you're
running AC through it, which sounds like some kind of choke, if that's
what you're doing. In which case you might want to rethink your
choice of magnetic core. At 60 Hz or so you can salvage the silcon
iron out of old transformer cores. Insulate with varnish, the induced
voltages are low. For higher frequencies, hit one of the remaining
ham radio supplier sites and look for powdered iron or ferrite cores,
they have much better properties at higher frequencies. Then you need
a book to tell you the formulas to get the performance out that you
want with the magnet parameters of those cores.

Stan

On Oct 7, 9:37*pm, Winston wrote:

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl insulated
mild steel wire. At only 249 feet per roll, I am concerned about the
need for splices, though.

Thanks!

--Winston
I do not understand your concern about splices. I do not think it
will make a noticeable amount of difference if you have a few breaks
in the wire rather than a continuous length.

Dan

wrote:

(...)

And steel is 99.9-99% iron.

I DAGS on 'iron wire' and 'steel wire'; came up with bupkis.

It's the little details that will get
you. My old, OLD electrical how-to from the teens and twenties shows
them using iron, not steel, wire for solenoid cores. The reason being
is that soft iron, not steel, wire will have little or no remaining
field once the current is turned off. You want it magnetized only
when the current is on. And eddy currents are only there if you're
running AC through it, which sounds like some kind of choke, if that's
what you're doing.

Yup. A.C. electromagnet is what I'm building.

In which case you might want to rethink your
choice of magnetic core.

I'd really like some enamel insulated iron wire, but none of my sources
carries it. I have a query into a supplier of ferromagnetic tape suggested
by Kevin Gallimore but I'm concerned that they deal in much larger
quantities than I need. I'm not expecting a response from them.

MIG wire is the nearest thing available.

Suggestions?

At 60 Hz or so you can salvage the silcon
iron out of old transformer cores.

Not really. This is a 10" long part. I'm not going to spend a
few hundred dollars for transformers to disassemble.

Insulate with varnish, the induced
voltages are low. For higher frequencies, hit one of the remaining
ham radio supplier sites and look for powdered iron or ferrite cores,
they have much better properties at higher frequencies. Then you need
a book to tell you the formulas to get the performance out that you
want with the magnet parameters of those cores.

I've looked into those and discovered they measure just a few percent of
the size that I need and don't have nearly the proper geometry or chemistry.
They are perfect, otherwise.


Thanks Stan.

--Winston

--

I'm still waiting for another sublime, transcendent flash of adequacy.

wrote:
On Oct 7, 9:37 pm, Winston wrote:

I am aware of McMaster 8867K25 which is a 0.062" diameter vinyl insulated
mild steel wire. At only 249 feet per roll, I am concerned about the
need for splices, though.

Thanks!

--Winston
I do not understand your concern about splices. I do not think it
will make a noticeable amount of difference if you have a few breaks
in the wire rather than a continuous length.

The core is small; there isn't room for a splice bulge.
The irony (Pun intended) is that I will slice off one end of the
core winding to create pole pieces (after they are epoxied).


Thanks, Dan.

--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.

In article , Winston
writes
Hi all,

I want to build up a magnetic core using a few hundred feet of 0.023"
diameter ER70-S6 MIG filler wire. To limit eddy current, I need to make
the wire non-conductive to low voltage (ca. 5.0V AC @ 60Hz) up to 100
degrees F (38 C).
Snip

I suspect that the insulating coating doesn't have to be perfect. Just a
thin layer of oxide would do the trick -after all the contact area
between the bundled wires is quite small. I noticed in the 'JP
Transformer' book that someone kindly posted the URL for that one method
used was to phosphate coat the iron. So just use one of the phosphoric
acid 'rust treatments' to give a thin coat of phosphate.

--
Chris Holford

Winston wrote:
I have a query into a supplier of ferromagnetic tape suggested
by Kevin Gallimore but I'm concerned that they deal in much larger
quantities than I need.

Tempel Steel sells it in coils.
I have called the application engineering departments of many companies,
explained a problem and had the applications guy sample me the quantity
I needed.
If all else fails, why wouldn't you stack some thin mild steel sheet to
the required thickness, clamp it down and mill out the core shape you
want? Dip each new lamination in thinned laquer, restack, and you are
good to go.
If you described the function of what you have in mind, (I'm seeing a
giant 60 Hz tape recorder head), perhaps some of the fellows could offer
more suggestions.

Kevin Gallimore

Chris Holford wrote:
So just use one of the phosphoric
acid 'rust treatments' to give a thin coat of phosphate.

Excellent! That is a whole lot less trouble than
the method I contemplated.

Thanks, Chris.

--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.

axolotl wrote:
Winston wrote:
I have a query into a supplier of ferromagnetic tape suggested
by Kevin Gallimore but I'm concerned that they deal in much larger
quantities than I need.

Tempel Steel sells it in coils.

http://www.tempel.com/home.asp
Thanks, I will check with them.

I have called the application engineering departments of many companies,
explained a problem and had the applications guy sample me the quantity
I needed.

Maybe if I spoke nicely with Tempel? Good idea!

If all else fails, why wouldn't you stack some thin mild steel sheet to
the required thickness, clamp it down and mill out the core shape you
want? Dip each new lamination in thinned laquer, restack, and you are
good to go.

That'll work, especially if I could get my hands on some
silicon steel sheet or the tape you mentioned.
Obviously, I could use regular old HRS as well.

If you described the function of what you have in mind, (I'm seeing a
giant 60 Hz tape recorder head), perhaps some of the fellows could offer
more suggestions.

You intuit well.
I hope to shrink small sheet metal dents from the 'accessible' side.

--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.

Winston wrote:
axolotl wrote:

(...)

If you described the function of what you have in mind, (I'm seeing a
giant 60 Hz tape recorder head), perhaps some of the fellows could
offer more suggestions.

You intuit well.
I hope to shrink small sheet metal dents from the 'accessible' side.

Like this:
http://www.youtube.com/watch?v=zSz87...eature=related

--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.

On Thu, 08 Oct 2009 14:04:33 -0700, the infamous Winston
scrawled the following:

wrote:

(...)

And steel is 99.9-99% iron.

I DAGS on 'iron wire' and 'steel wire'; came up with bupkis.

It's the little details that will get
you. My old, OLD electrical how-to from the teens and twenties shows
them using iron, not steel, wire for solenoid cores. The reason being
is that soft iron, not steel, wire will have little or no remaining
field once the current is turned off. You want it magnetized only
when the current is on. And eddy currents are only there if you're
running AC through it, which sounds like some kind of choke, if that's
what you're doing.

Yup. A.C. electromagnet is what I'm building.

You're going to snatch those Big Wheels right out from under those
noisyarse little bitty bastids, aren't you? Excellent!

ENGAGE!


In which case you might want to rethink your
choice of magnetic core.

I'd really like some enamel insulated iron wire, but none of my sources
carries it. I have a query into a supplier of ferromagnetic tape suggested
by Kevin Gallimore but I'm concerned that they deal in much larger
quantities than I need. I'm not expecting a response from them.

MIG wire is the nearest thing available.

Suggestions?

Try www.Mouser.com . They used to provide -anything- in hardware to us
when I worked at Southcom. (No, not the military one. SCI, which was
snatched by Loral in the late '70s)


At 60 Hz or so you can salvage the silcon
iron out of old transformer cores.

Not really. This is a 10" long part. I'm not going to spend a
few hundred dollars for transformers to disassemble.

Um, you're really building yourself a ten-incher? Crikey! Your sales
will go into the millions within weeks if it works. And women;
there'll be lots and lots of women. bseg

--
Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)
--

On Thu, 08 Oct 2009 16:07:40 -0700, the infamous Winston
scrawled the following:

Winston wrote:
axolotl wrote:

(...)

If you described the function of what you have in mind, (I'm seeing a
giant 60 Hz tape recorder head), perhaps some of the fellows could
offer more suggestions.

You intuit well.
I hope to shrink small sheet metal dents from the 'accessible' side.

Like this:
http://www.youtube.com/watch?v=zSz87...eature=related

OK, cool (but not nearly as cool as an electronic 10-incher.)

My across-the-street neighbor can use one of those right now. He
backed into something and rolled a dent into the left rear QP.
I told him to find a local "paintless dent removal" shop, guys who use
suction cups and balloons to pop panels back into shape. I guess they
also can use this type of technology nowadays.

Is this called induction shrinking?

--
Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)
--

On Thu, 08 Oct 2009 16:07:40 -0700, the infamous Winston
scrawled the following:

Winston wrote:
axolotl wrote:

(...)

If you described the function of what you have in mind, (I'm seeing a
giant 60 Hz tape recorder head), perhaps some of the fellows could
offer more suggestions.

You intuit well.
I hope to shrink small sheet metal dents from the 'accessible' side.

Like this:
http://www.youtube.com/watch?v=zSz87...eature=related

So, you're hoping to save yourself $2,300, eh? thud
http://www.autobodytoolmart.com/auto...16081-100.aspx

--
Adults are obsolete children. --Dr. Seuss (Theodore Geisel, 1904-1991)
--

Paul Hovnanian P.E. wrote:
Winston wrote:
Bob Engelhardt wrote:
Winston wrote:
...
How would you approach this particular challenge?
Magnet wire. E.g., from a MOT. Bob
I've got the current - carrying wire handled.
That'll be enamel - insulated copper, equivalent
to the magnet wire you mention. The challenge
is in sourcing some insulated iron or mild steel
that can be easily formed into a core for the
magnetic (not electrical) circuit.

Gut a busted microwave oven and rewind the transformer.

I want a longish "E" core in hopes that I could
concentrate a large amount of flux off the end
of a smallish pole piece. (Quiet, Larry)

Thanks!

--Winston


--

I'm still waiting for another sublime, transcendent flash of adequacy.