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[email protected] March 17th 20 07:06 PM

mag base remagnetizing
 
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric

David Billington[_2_] March 17th 20 09:04 PM

mag base remagnetizing
 
On 17/03/2020 18:06, wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


The magnets in my cheap magnetic bases are black ceramic magnets. I did
once re-magnetise a screwdriver by putting it into a coil of wire and
connecting it a DC power supply as I didn't have any permanent magnets
handy.


Richard Smith[_4_] March 18th 20 10:11 AM

mag base remagnetizing
 
writes:

On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


I save the magnetising assembly at a magnet factory in Sheffield, UK,
a long time ago.
Which leads me to voice agreement with Eric.
It fitted on top of a pallet, took some huge current, dust was
flying and their were major creaking sounds as enormous forces
resulted.
Rich S

Jim Wilkins[_2_] March 18th 20 12:31 PM

mag base remagnetizing
 
"Richard Smith" wrote in message
...
writes:

On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was
thinking
about a large capacitor and some turns of wire on EI transformer
core
with the Is removed and the indicator base across the center and
one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a
new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The
alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


I save the magnetising assembly at a magnet factory in Sheffield,
UK,
a long time ago.
Which leads me to voice agreement with Eric.
It fitted on top of a pallet, took some huge current, dust was
flying and their were major creaking sounds as enormous forces
resulted.
Rich S


I've built 1000A test stations for devices such as electric locomotive
controllers. The construction is considerably different from normal
electronics, requiring copper buss bars, crimpers for 4/0 welding
cable lugs, mechanically strong and heat resistant insulators etc. All
conductors must be well supported to resist the magnetic attraction
between them and to the steel chassis. Common test equipment won't
measure the high currents or microOhm resistances involved.

My personal test gear collection includes second-hand lab grade and
new import hobby grade shunts like this
https://www.amazon.com/AMMETER-SHUNT.../dp/B005BHPG6K
to measure AC and DC current and a 1000V hipot tester to find
accidental shorts or leakage, mainly keep shocks or exploding wires
fom putting me in the hospital.



Pete Keillor[_2_] March 18th 20 01:07 PM

mag base remagnetizing
 
On Wed, 18 Mar 2020 07:31:34 -0400, "Jim Wilkins"
wrote:

"Richard Smith" wrote in message
...
writes:

On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was
thinking
about a large capacitor and some turns of wire on EI transformer
core
with the Is removed and the indicator base across the center and
one side
leg.

How are these magnetized at the factory?
Probably your best bet is to replace the old alnico magnet with a
new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The
alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


I save the magnetising assembly at a magnet factory in Sheffield,
UK,
a long time ago.
Which leads me to voice agreement with Eric.
It fitted on top of a pallet, took some huge current, dust was
flying and their were major creaking sounds as enormous forces
resulted.
Rich S


I've built 1000A test stations for devices such as electric locomotive
controllers. The construction is considerably different from normal
electronics, requiring copper buss bars, crimpers for 4/0 welding
cable lugs, mechanically strong and heat resistant insulators etc. All
conductors must be well supported to resist the magnetic attraction
between them and to the steel chassis. Common test equipment won't
measure the high currents or microOhm resistances involved.

My personal test gear collection includes second-hand lab grade and
new import hobby grade shunts like this
https://www.amazon.com/AMMETER-SHUNT.../dp/B005BHPG6K
to measure AC and DC current and a 1000V hipot tester to find
accidental shorts or leakage, mainly keep shocks or exploding wires
fom putting me in the hospital.


Reminds me of the old mag cells. A building was a row of pots up one
side and down the other electrically in series, running at about
30,000 amps. The workers commonly stored their tools by just slapping
them on a buss bar above a cell. There was a massive tool drop every
time they took a cell building down.

Bob Engelhardt March 18th 20 03:43 PM

mag base remagnetizing
 
On 3/18/2020 8:07 AM, Pete Keillor wrote:
Reminds me of the old mag cells. A building was a row of pots up one
side and down the other ...


What's a mag cell/building?

Clare Snyder March 19th 20 02:50 AM

mag base remagnetizing
 
On Wed, 18 Mar 2020 09:11:53 +0000, Richard Smith
wrote:

writes:

On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


I save the magnetising assembly at a magnet factory in Sheffield, UK,
a long time ago.
Which leads me to voice agreement with Eric.
It fitted on top of a pallet, took some huge current, dust was
flying and their were major creaking sounds as enormous forces
resulted.
Rich S

I have some axial field servo motors. They have a magnetizing loop
(#14 wire)-that they sharge with a capacitoe to top up the feild after
they are assembled because without the small gap the magnets cannot
hold a full field (apparently they quite quickly drop to about half
strength if you dissassemble the motor) They hit that coil with close
to 1000 amps for a millisecond or so to do the deed.

Jim Wilkins[_2_] March 19th 20 12:32 PM

mag base remagnetizing
 
"Clare Snyder" wrote in message
...
...
I have some axial field servo motors. They have a magnetizing loop
(#14 wire)-that they sharge with a capacitoe to top up the feild
after
they are assembled because without the small gap the magnets cannot
hold a full field (apparently they quite quickly drop to about half
strength if you dissassemble the motor) They hit that coil with
close
to 1000 amps for a millisecond or so to do the deed.


How do they keep the LC circuit from oscillating? If it's a clamp
diode I'm curious which one they chose to handle 1000A. The energy it
converts to heat is 0.5CV^2.

Some components such as diodes and breakers have a one-time surge
rating tht's far above their normal operating current but AFAIK they
aren't normlly tested for it in production, as it may degrade the
part.

http://www.cooperindustries.com/cont...ing_Rating.pdf



Pete Keillor[_2_] March 19th 20 12:42 PM

mag base remagnetizing
 
On Wed, 18 Mar 2020 10:43:08 -0400, Bob Engelhardt
wrote:

On 3/18/2020 8:07 AM, Pete Keillor wrote:
Reminds me of the old mag cells. A building was a row of pots up one
side and down the other ...


What's a mag cell/building?


Electolytic production of magnesium metal from magnesium chloride,
which was extracted from seawater. There were about 30 pots in one
building. Each pot was a heavy steel pot, refractory lined, with
about 10 10" diameter graphite anodes descending through the insulated
lid into the bath within an inch or so of conical steel cathodes.
Voltage drop was a couple volts, liquid magnesium metal and chlorine
gas were produced.

It took a special breed to work in the cell buildings, but they did
get a lot of breaks to avoid heat exhaustion. My cousins that grew up
like I did in the rice fields worked there during a strike, said it
wasn't much hotter than shoveling levees in a rice field, and a lot
easier.

Pete Keillor

Cydrome Leader March 22nd 20 11:02 PM

mag base remagnetizing
 
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


Any details on these magnetizers?

Clifford Heath March 22nd 20 11:40 PM

mag base remagnetizing
 
On 23/3/20 9:02 am, Cydrome Leader wrote:
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


Any details on these magnetizers?


I had some blade magnets made for a guitar pickup, cut with a diamond
from neutral (but permanent) ferrite into slabs 120x22x4mm and
magnetised across the 22mm dimension in one of these machines.

It was a small machine, about 1.6m long, 1.2m high, with a C-shaped
armature (gap upwards) about 40cm broad with a massive winding like a
small oil drum across the bottom. The ferrites were spaced up with soft
magnetic spacer blocks and clamped in to remove most of the air gaps.

The operator hit the switch and the lights dimmed, the concrete slab
floor noticably thrummed, for about 30-40 seconds, and the magnets were
cooked. I believe it was being fed from a rectified three-phase feed,
which is 50Hz here.

Does that give you some idea?

Clifford Heath.

Cydrome Leader March 23rd 20 05:47 AM

mag base remagnetizing
 
Clare Snyder wrote:
On Wed, 18 Mar 2020 09:11:53 +0000, Richard Smith
wrote:

writes:

On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?
Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


I save the magnetising assembly at a magnet factory in Sheffield, UK,
a long time ago.
Which leads me to voice agreement with Eric.
It fitted on top of a pallet, took some huge current, dust was
flying and their were major creaking sounds as enormous forces
resulted.
Rich S

I have some axial field servo motors. They have a magnetizing loop
(#14 wire)-that they sharge with a capacitoe to top up the feild after
they are assembled because without the small gap the magnets cannot
hold a full field (apparently they quite quickly drop to about half
strength if you dissassemble the motor) They hit that coil with close
to 1000 amps for a millisecond or so to do the deed.


Do you know what sort of magnets these motors had? From what I've seen,
Alnico magnets are the ones that lose their fields the easiest. This is
why even the decent ones ships with keeper plates.

I suspect it's usually Alnico in these mag bases, had to send one back to
Mitutoyo once, it just lost it's field and wasn't stored in the on
position. They just swapped it for a new one.

There's little chance I'll locate the same sized rare earth to retrofit
into the base itself. I don't want to mangle the faceplate to tear into
this one either. I have a supply of large electrolytic caps and some mega
SCRs. Don't mind trying something out if the magnetizing currents and
times aren't something too insane.

Michael Terrell March 23rd 20 05:52 AM

mag base remagnetizing
 
On Sunday, March 22, 2020 at 6:02:38 PM UTC-4, Cydrome Leader wrote:
etpm wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


Any details on these magnetizers?



I knew an old man (25+ years ago) in Mt. Dora Florida who restored 'Huff and Puff' engines. His prize possessions were a photo of him selling an engine to 'Grandpaw Jones' (and an uncashed check) who was part of the Grand Ole Opry'.

He also rebuild Magnetos and sold magnet rechargers that he built in a 10' x 20' rental warehouse. He used a large electric hacksaw to cut a large bundle of soft iron rods into the cores, and wound the coils on his lathe. There are businesses that recharge magnetos that may be able to do what the OP needs.

Bob Engelhardt March 23rd 20 03:17 PM

mag base remagnetizing
 
On 3/23/2020 12:47 AM, Cydrome Leader wrote:
.... I have a supply of large electrolytic caps and some mega
SCRs. Don't mind trying something out if the magnetizing currents and
times aren't something too insane.


I once tried to re-magnetize an indicator base & don't remember any
details, just that it involved really large current and didn't work very
well.

I do remember what I thought was a neat trick for switching. The switch
was 2 copper leafs, separated by an air gap. To turn it on you hit it
with a hammer! Very fast and very low resistance as the oxide is
displaced and you have a large area bare copper-copper contact.



[email protected] March 23rd 20 05:23 PM

mag base remagnetizing
 
On Sun, 22 Mar 2020 22:02:36 +0000 (UTC), Cydrome Leader
wrote:

wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?

Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


Any details on these magnetizers?


https://www.coolmagnetman.com/Magnetizing.pdf
See below from the link above.

8
5. Pulse Analysis
All of the capacit
ive
-
discharge magnetizer circuits shown may be modeled as a series
combination of a capacitor, a resistor, and an inductance. The
electrical resistance must include the
resistance of the source as well as that of the fixture (especially
including the ESR,
equivalent series
resistance, of the capacitors), and also includes components from
eddy
-
current conduction in surrounding
structures, in the magnet itself, from “skin effect” in the
conductors, etc. In addition, the resistance may
increase during the
period of the pulse (by perhaps 30%) due to heating in the fixture
(the resistance of
copper and most other metals increases with temperature). The
inductance of a fixture containing steel
pole material is dramatically affected by whether the fixture is
below or above magnetic saturation (the
inductance dropping greatly at currents above saturation). Other
effects may be of importance too, such as
the retention of energy by the electrolyte of the capacitors, the
absorption of energy by the magnet, and
other nonlinearities. Nonetheless, in many cases the overall system
behavior of the magnetizer and fixture
is modeled to sufficient accuracy by assuming constant values for the
resistance, inductance, and
capacitance. Even where the assumption of const
ant values of these parameters is not justified for final
design, the linear analysis may provide a good first approximation and
a check on the calculations. Where
the linear approach using fixed values is not accurate enough,
however, a computer simulat
ion including all
nonlinear effects may be used. The method is described in detail in
the bound notes (reference 7).
6. Design of Fixtures
6.1 General
There are five types of conditions which must be met in the
design of a magn
etizing fixtu
(1) The fixture, in combination with the magnetizer,
must provide a magnetic field of sufficient
strength and in the proper direction to saturate the magnet. The
directional requirement is usually not much
of a problem in m
agnetizing anisotropic materials, which can only be magnetized along a
particular
directional line (although with either sense, i. e. from right to
left, or from left to right, along that line).
This is because the field component in the required directio
n varies as the cosine of the angle between the
two, which does not change much for angles up to ten degrees of arc or
so. If the material is isotropic,
however, meaning that it can be magnetized in any direction, the
direction of field may be of much gre
ater
concern.
The magnet domains themselves align in a very short time (on the
order of 10
-
8
to 10
-
9
seconds). The
field may have to be maintained for a significantly longer time,
however, in order to overcome electrical
eddy currents, which may oc
cur in the fixture, the magnet itself, or in associated structure.
(2) The part must be held in the fixture in the proper
orientation, accurately but without imposing
stresses on the part during magnetizing (and possible thermal cycling
as we
ll) without breaking it. The part
must also not be damaged, chipped, or broken as it is being removed
from the fixture, or as it is loaded.
(3) The windings must be strong enough, or must be
reinforced to be strong enough, to withstand
the m
echanical forces on them during the magnetizing pulse, either to fail
due to ultimate stress limits or, at
a much lower level, in fatigue (after a number of cycles). Fields
high enough to magnetize high
-
energy
magnets often cause forces which could pull
apart copper conductors in a single pulse, if they are not
strengthened by other means. These forces are also more than strong
enough to bend, crush, or extrude out
epoxy potting plastics.
(4) The thermal requirements must be met. the near
-
i
nstantaneous temperature rise in the windings
during the pulse occurs too quickly for much of the heat to escape
across even a single thin layer of
electrical insulation. If this rise is too great, the insulation will
fail, on a single pulse. A thermal t
ime
constant exists for this effect, and a thermal mass, which is often
significantly different from that of the
fixture as a whole (that is, the time constant is shorter than that of
the fixture, and the mass is less). Both
must be taken into account. A
n extreme example is a large “C” frame fixture, used for automatically

Jim Wilkins[_2_] March 24th 20 12:36 AM

mag base remagnetizing
 
"Bob Engelhardt" wrote in message
...
On 3/23/2020 12:47 AM, Cydrome Leader wrote:
... I have a supply of large electrolytic caps and some mega
SCRs. Don't mind trying something out if the magnetizing currents
and
times aren't something too insane.


I once tried to re-magnetize an indicator base & don't remember any
details, just that it involved really large current and didn't work
very well.

I do remember what I thought was a neat trick for switching. The
switch was 2 copper leafs, separated by an air gap. To turn it on
you hit it with a hammer! Very fast and very low resistance as the
oxide is displaced and you have a large area bare copper-copper
contact.


An SCR switch blocks the LC oscillation that would immediately
demagnetize the magnet. You still need a flyback diode to suppress the
reverse voltage spike.

https://forum.allaboutcircuits.com/t...athode.111625/
"As a side note, please be advised that proper (mechanical) 'clamping'
is essential to device operation and integrity and not merely for
heat-sink efficiency! It seems the construction 'expects' a precise
compressive force (should be found in the Specs) --- Indeed many such
units will test (electrically) open while 'uncompressed'..."

The actual SCR is a thin silicon wafer slice between the anode and
cathode contact disks. The specified clamping pressure ensures that
enough of the area of the wafer disk will be in electrical contact to
distribute the current and the heat it produces across the wafer
rather than allowing it to concentrate in a few spots and burn out the
SCR. Driving the gate harder than the minimum helps rapidly spread the
initial area(s) of conduction and even out the instantaneous heating.

The clamps GE sent us for our test stations consisted of two U
channels connected by bolts. The dimples accept alignment pins that
center the anode and cathode contact disks while you are assembling
the awkward sandwich of SCR, contacts, insulation and clamps. We used
a simple sheetmetal gauge that aligned two points when the channels
had bent far enough to produce the specified clamping pressure.

http://appliedps.com/clamp-heatsink-assemblies-kits

We didn't need heatsinks to test the SCRs with one or a few
full-current pulses. The heat generation can be estimated as 1 Watt
per Amp continuously, or 1 Joule per Coulomb for a capacitive
discharge pulse.



Jim Wilkins[_2_] March 24th 20 12:43 AM

mag base remagnetizing
 
wrote in message
...

https://www.coolmagnetman.com/Magnetizing.pdf


Nice article. Rail gun power supplies have the same problems.

Search that subject at your own risk.



whit3rd March 24th 20 08:26 AM

mag base remagnetizing
 
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7, wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader


The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.


There's a two-part magnetization process for alnico, you have to observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from Lincoln, Miller,
Hobart, etc. and that's what it'll take.

Jim Wilkins[_2_] March 24th 20 01:10 PM

mag base remagnetizing
 
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader


The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.


There's a two-part magnetization process for alnico, you have to
observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.


Arc welders inherently limit short circuit current by designed-in self
inductance, core saturation, etc and can't easily be tweaked to
deliver higher current in a short pulse. Also their rated current is
at 20-25V which doesn't allow for much wire resistance. At 20V the 0.1
Ohm resistance of a coil wound with 100' of 10AWG copper wire would
limit the current to around 200A. Unless you can reuse the wire in a
solar system it's cheaper to replace the magnetic base.

Perhaps a motor shop can repolarize it.



[email protected] March 24th 20 05:14 PM

mag base remagnetizing
 
On Tue, 24 Mar 2020 00:26:44 -0700 (PDT), whit3rd
wrote:

On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7, wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader


The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.


There's a two-part magnetization process for alnico, you have to observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from Lincoln, Miller,
Hobart, etc. and that's what it'll take.

My 300 amp Miller would not provide enough current for decent
magnetization. Not even close.
Eric

Cydrome Leader March 24th 20 08:55 PM

mag base remagnetizing
 
Clifford Heath wrote:
On 23/3/20 9:02 am, Cydrome Leader wrote:
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
wrote:

Has anybody remagnetized a rotary on-off mag base before? I was thinking
about a large capacitor and some turns of wire on EI transformer core
with the Is removed and the indicator base across the center and one side
leg.

How are these magnetized at the factory?
Probably your best bet is to replace the old alnico magnet with a new
rare earth magnet. This is because if the alnico magnet is removed
from the magnetic circuit it loses a lot of its magnetism. The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
Eric


Any details on these magnetizers?


I had some blade magnets made for a guitar pickup, cut with a diamond
from neutral (but permanent) ferrite into slabs 120x22x4mm and
magnetised across the 22mm dimension in one of these machines.

It was a small machine, about 1.6m long, 1.2m high, with a C-shaped
armature (gap upwards) about 40cm broad with a massive winding like a
small oil drum across the bottom. The ferrites were spaced up with soft
magnetic spacer blocks and clamped in to remove most of the air gaps.

The operator hit the switch and the lights dimmed, the concrete slab
floor noticably thrummed, for about 30-40 seconds, and the magnets were
cooked. I believe it was being fed from a rectified three-phase feed,
which is 50Hz here.

Does that give you some idea?

Clifford Heath.


Only vaguely. I get that there are giant magnetizers, but in the grand
scheme of things, there isnt that much iron in the circuit of a mag base
and it will saturate at field strengths that don't require a 50 ton
machine warehouse and three phase power.

Anybody got some dead-ish bases for sale for the price of shipping and a
few dollars?


Clare Snyder March 24th 20 09:10 PM

mag base remagnetizing
 
On Tue, 24 Mar 2020 09:14:40 -0700, wrote:

On Tue, 24 Mar 2020 00:26:44 -0700 (PDT), whit3rd
wrote:

On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7, wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader


The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.


There's a two-part magnetization process for alnico, you have to observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from Lincoln, Miller,
Hobart, etc. and that's what it'll take.

My 300 amp Miller would not provide enough current for decent
magnetization. Not even close.
Eric

Might work to charge the capacitor bank, but definitely won't do the
magnetizing unless you have a lot of turns - it's ampere turns that
make the feild strength - and too many turns increase the
inductance/reluctance and slow down both the build-up and collapse of
the feild.

Clifford Heath March 24th 20 11:58 PM

mag base remagnetizing
 
On 24/3/20 11:10 pm, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader


The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.


There's a two-part magnetization process for alnico, you have to
observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.


Arc welders inherently limit short circuit current...


What about a spot welder, hooked up to a fat coil of copper tube on a
magnetic core?

Robert Nichols March 25th 20 12:05 AM

mag base remagnetizing
 
On 3/24/20 3:10 PM, Clare Snyder wrote:
On Tue, 24 Mar 2020 09:14:40 -0700, wrote:

On Tue, 24 Mar 2020 00:26:44 -0700 (PDT), whit3rd
wrote:

On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7, wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader

The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.

There's a two-part magnetization process for alnico, you have to observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from Lincoln, Miller,
Hobart, etc. and that's what it'll take.

My 300 amp Miller would not provide enough current for decent
magnetization. Not even close.
Eric

Might work to charge the capacitor bank, but definitely won't do the
magnetizing unless you have a lot of turns - it's ampere turns that
make the feild strength - and too many turns increase the
inductance/reluctance and slow down both the build-up and collapse of
the feild.


The setups from some of the experimenters that use high-current pulses to
shrink coins might be a good place to start.

https://www.google.com/search?as_q=shrink+coin

Delivering 100,000 Amperes from capacitors charged to 12,000 Volts is a bit
of a challenge, though.

--
Bob Nichols AT comcast.net I am "RNichols42"

Jim Wilkins[_2_] March 25th 20 12:31 AM

mag base remagnetizing
 
"Clifford Heath" wrote in message
...
On 24/3/20 11:10 pm, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader

The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.

There's a two-part magnetization process for alnico, you have to
observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.


Arc welders inherently limit short circuit current...


What about a spot welder, hooked up to a fat coil of copper tube on
a magnetic core?


I've used a pedestal spot welder on sheet steel and don't remember the
metal being pulled into the current loop or otherwise disturbed when I
stepped on the pedal.



Jim Wilkins[_2_] March 25th 20 12:53 AM

mag base remagnetizing
 
"Robert Nichols" wrote
in message ...
On 3/24/20 3:10 PM, Clare Snyder wrote:
On Tue, 24 Mar 2020 09:14:40 -0700, wrote:

On Tue, 24 Mar 2020 00:26:44 -0700 (PDT), whit3rd

wrote:

On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader

The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups
for
doing this and they are not trivial.

There's a two-part magnetization process for alnico, you have to
observe the
built-in (at ceramic-firing time) polarity when you apply
current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.
My 300 amp Miller would not provide enough current for decent
magnetization. Not even close.
Eric

Might work to charge the capacitor bank, but definitely won't do
the
magnetizing unless you have a lot of turns - it's ampere turns that
make the feild strength - and too many turns increase the
inductance/reluctance and slow down both the build-up and collapse
of
the feild.


The setups from some of the experimenters that use high-current
pulses to
shrink coins might be a good place to start.

https://www.google.com/search?as_q=shrink+coin

Delivering 100,000 Amperes from capacitors charged to 12,000 Volts
is a bit
of a challenge, though.

--
Bob Nichols AT comcast.net I am "RNichols42"


12KV arcing across contacts is enough to generate X-rays.



David Billington[_2_] March 25th 20 01:19 AM

mag base remagnetizing
 
On 24/03/2020 23:31, Jim Wilkins wrote:
"Clifford Heath" wrote in message
...
On 24/3/20 11:10 pm, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
There's a two-part magnetization process for alnico, you have to
observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.
Arc welders inherently limit short circuit current...

What about a spot welder, hooked up to a fat coil of copper tube on
a magnetic core?

I've used a pedestal spot welder on sheet steel and don't remember the
metal being pulled into the current loop or otherwise disturbed when I
stepped on the pedal.


I thought about a spot welder as mine is about 6000A hand held unit but
it's AC so wouldn't be any good. Mine does exhibit a bit of buzz and can
cause near items to buzz a bit but the magnetic field definitely upset
my Swatch watch, not permanently but I had to read the instructions to
reset the time, I took it off after doing that a few times.


Clifford Heath March 25th 20 01:41 AM

mag base remagnetizing
 
On 25/3/20 11:19 am, David Billington wrote:
On 24/03/2020 23:31, Jim Wilkins wrote:
"Clifford Heath" wrote in message
...
On 24/3/20 11:10 pm, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
The alnico
magnets inÂ* old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
There's a two-part magnetization process for alnico, you have to
observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc.Â*Â*Â* and that's what it'll take.
Arc welders inherently limit short circuit current...
What about a spot welder, hooked up to a fat coil of copper tube on
a magnetic core?

I've used a pedestal spot welder on sheet steel and don't remember the
metal being pulled into the current loop or otherwise disturbed when I
stepped on the pedal.


I thought about a spot welder as mine is about 6000A hand held unit but
it's AC so wouldn't be any good. Mine does exhibit a bit of buzz and can
cause near items to buzz a bit but the magnetic field definitely upset
my Swatch watch, not permanently but I had to read the instructions to
reset the time, I took it off after doing that a few times.


I have a small spot welder for welding s/s dental wires and it uses a
contacter to dump a capacitor into a chonky transformer - so it's mostly
a big DC current pulse. If that was fed through a suitable winding it
would work, to some extent.

whit3rd March 25th 20 02:12 AM

mag base remagnetizing
 
On Tuesday, March 24, 2020 at 5:10:19 AM UTC-7, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader


The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly.


Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.


Arc welders inherently limit short circuit current by designed-in self
inductance, core saturation, etc and can't easily be tweaked to
deliver higher current in a short pulse.


The current ought NOT to be delivered in a short pulse (it has to
penetrate the metal pole pieces as well as the magnet, which takes some time)
which is why it has to be a DC welder. The induction is not just 'amps',
but is 'amp-turns', so a few turns of wire will multiply the effect of the
welder current accordingly.

Also their rated current is
at 20-25V which doesn't allow for much wire resistance. At 20V the 0.1
Ohm resistance of a coil wound with 100' of 10AWG copper wire...


I'm thinking it's more on the order of five feet of wire, maybe 5 or 10 or so turns
around a circa 1.5" bar (it just has to be as thick as the pole pieces it's being held
against). I'd consider using one of my auto jumper cables instead of ten-gage.

Other than using the magnet holder completely assembled, it'd be a nuisance to orient the
magnetic field appropriately. Thinking about it, some of my bench vises are just about
the right shape to take windings and hold against the mag base for this task.

Cydrome Leader March 25th 20 02:16 AM

mag base remagnetizing
 
Robert Nichols wrote:
On 3/24/20 3:10 PM, Clare Snyder wrote:
On Tue, 24 Mar 2020 09:14:40 -0700, wrote:

On Tue, 24 Mar 2020 00:26:44 -0700 (PDT), whit3rd
wrote:

On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7, wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader

The alnico
magnets in old and/or inexpensive mag bases were/are magnetized after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.

There's a two-part magnetization process for alnico, you have to observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from Lincoln, Miller,
Hobart, etc. and that's what it'll take.
My 300 amp Miller would not provide enough current for decent
magnetization. Not even close.
Eric

Might work to charge the capacitor bank, but definitely won't do the
magnetizing unless you have a lot of turns - it's ampere turns that
make the feild strength - and too many turns increase the
inductance/reluctance and slow down both the build-up and collapse of
the feild.


The setups from some of the experimenters that use high-current pulses to
shrink coins might be a good place to start.

https://www.google.com/search?as_q=shrink+coin

Delivering 100,000 Amperes from capacitors charged to 12,000 Volts is a bit
of a challenge, though.


Not really. I've successfully done coin crushing and the setup doesn't
need to be overly complex like all the junk on google. The hype about
specially crafted parts, bullet proof chambers etc. is pure puffery and
marketing bull****.

There probably isn't a need for a one-use solenoid for remagnetizing a mag
base though, or the energy levels needed to crush a coin.

I sold my can crushing capacitor bank, but have some other large can
electrolytics. They're not really special low ESR versions but might be
coaxed into limited pulse use. The required amp-turns remains a mystery
though.


David Billington[_2_] March 25th 20 02:19 AM

mag base remagnetizing
 
On 25/03/2020 00:41, Clifford Heath wrote:
On 25/3/20 11:19 am, David Billington wrote:
On 24/03/2020 23:31, Jim Wilkins wrote:
"Clifford Heath" wrote in message
...
On 24/3/20 11:10 pm, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader
The alnico
magnets inÂ* old and/or inexpensive mag bases were/are magnetized
after
assembly. This takes a LOT of current. I have seen the setups for
doing this and they are not trivial.
There's a two-part magnetization process for alnico, you have to
observe the
built-in (at ceramic-firing time) polarity when you apply current.
It WILL magnetize one direction, not the other.

Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc.Â*Â*Â* and that's what it'll take.
Arc welders inherently limit short circuit current...
What about a spot welder, hooked up to a fat coil of copper tube on
a magnetic core?
I've used a pedestal spot welder on sheet steel and don't remember the
metal being pulled into the current loop or otherwise disturbed when I
stepped on the pedal.


I thought about a spot welder as mine is about 6000A hand held unit
but it's AC so wouldn't be any good. Mine does exhibit a bit of buzz
and can cause near items to buzz a bit but the magnetic field
definitely upset my Swatch watch, not permanently but I had to read
the instructions to reset the time, I took it off after doing that a
few times.


I have a small spot welder for welding s/s dental wires and it uses a
contacter to dump a capacitor into a chonky transformer - so it's
mostly a big DC current pulse. If that was fed through a suitable
winding it would work, to some extent.


OK a different sort to mine which is basically a heavy high current
output mains transformer intended for welding sheet metal upto 2mm + 2mm
with about a 5 - 6mm spot.


Clifford Heath March 25th 20 02:51 AM

mag base remagnetizing
 
On 25/3/20 12:12 pm, whit3rd wrote:
On Tuesday, March 24, 2020 at 5:10:19 AM UTC-7, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader

The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly.


Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.


Arc welders inherently limit short circuit current by designed-in self
inductance, core saturation, etc and can't easily be tweaked to
deliver higher current in a short pulse.


The current ought NOT to be delivered in a short pulse (it has to
penetrate the metal pole pieces as well as the magnet, which takes some time)
which is why it has to be a DC welder. The induction is not just 'amps',
but is 'amp-turns', so a few turns of wire will multiply the effect of the
welder current accordingly.

Also their rated current is
at 20-25V which doesn't allow for much wire resistance. At 20V the 0.1
Ohm resistance of a coil wound with 100' of 10AWG copper wire...


I'm thinking it's more on the order of five feet of wire, maybe 5 or 10 or so turns
around a circa 1.5" bar (it just has to be as thick as the pole pieces it's being held
against). I'd consider using one of my auto jumper cables instead of ten-gage.


Flattened copper water pipe is better. Tightly packed square section is
better still (approximately square winding cross-section, too).

whit3rd March 25th 20 03:27 AM

mag base remagnetizing
 
On Tuesday, March 24, 2020 at 3:58:09 PM UTC-7, Clifford Heath wrote:
On 24/3/20 11:10 pm, Jim Wilkins wrote:


Arc welders inherently limit short circuit current...


What about a spot welder, hooked up to a fat coil of copper tube on a
magnetic core?


The spot welders I'm familiar with are all AC, so they'll only magnetize as deeply
as the field-penetration-distance after one half cycle (if you can time it so a full
half-cycle is the end of the conduction). That won't usually be enough for magnetization
of a sizeable lump.

If you could spin the lump, so that the lump turns 180 degrees WITH the AC
reversal, it'd be a possibility.

Clare Snyder March 25th 20 04:15 AM

mag base remagnetizing
 
On Tue, 24 Mar 2020 18:12:48 -0700 (PDT), whit3rd
wrote:

On Tuesday, March 24, 2020 at 5:10:19 AM UTC-7, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,
wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader

The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly.


Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.


Arc welders inherently limit short circuit current by designed-in self
inductance, core saturation, etc and can't easily be tweaked to
deliver higher current in a short pulse.


The current ought NOT to be delivered in a short pulse (it has to
penetrate the metal pole pieces as well as the magnet, which takes some time)
which is why it has to be a DC welder. The induction is not just 'amps',
but is 'amp-turns', so a few turns of wire will multiply the effect of the
welder current accordingly.

Also their rated current is
at 20-25V which doesn't allow for much wire resistance. At 20V the 0.1
Ohm resistance of a coil wound with 100' of 10AWG copper wire...


I'm thinking it's more on the order of five feet of wire, maybe 5 or 10 or so turns
around a circa 1.5" bar (it just has to be as thick as the pole pieces it's being held
against). I'd consider using one of my auto jumper cables instead of ten-gage.

Other than using the magnet holder completely assembled, it'd be a nuisance to orient the
magnetic field appropriately. Thinking about it, some of my bench vises are just about
the right shape to take windings and hold against the mag base for this task.

For the price of a harbor fright mag base you really can't affoed to
re-magnetize one - I know , it HURTS to throw something away that you
might be able to repair, but even I have been known to "cut my losses"
on occaision.

Jim Wilkins[_2_] March 25th 20 01:01 PM

mag base remagnetizing
 
"whit3rd" wrote in message
...
On Tuesday, March 24, 2020 at 5:10:19 AM UTC-7, Jim Wilkins wrote:
"whit3rd" wrote in message
...
On Tuesday, March 17, 2020 at 11:06:10 AM UTC-7,

wrote:
On Sat, 14 Mar 2020 21:25:20 +0000 (UTC), Cydrome Leader

The alnico
magnets in old and/or inexpensive mag bases were/are magnetized
after
assembly.


Usually, metalworkers have access to high DC current sources from
Lincoln, Miller,
Hobart, etc. and that's what it'll take.


Arc welders inherently limit short circuit current by designed-in
self
inductance, core saturation, etc and can't easily be tweaked to
deliver higher current in a short pulse.


The current ought NOT to be delivered in a short pulse (it has to
penetrate the metal pole pieces as well as the magnet, which takes
some time)
which is why it has to be a DC welder. The induction is not just
'amps',
but is 'amp-turns', so a few turns of wire will multiply the effect
of the
welder current accordingly.

Also their rated current is
at 20-25V which doesn't allow for much wire resistance. At 20V the
0.1
Ohm resistance of a coil wound with 100' of 10AWG copper wire...


I'm thinking it's more on the order of five feet of wire, maybe 5 or
10 or so turns
around a circa 1.5" bar (it just has to be as thick as the pole
pieces it's being held
against). I'd consider using one of my auto jumper cables instead
of ten-gage.


You can obtain the maximum Amp-turns if the coil resistance is close
to the welder's output impedance. A short, thick jumper cable won't
allow as many turns and will still be limited to the welder's short
circuit (stuck electrode) current.

Then you have to figure or measure the temperature rise vs pulse
duration to avoid damaging the insulation of the expensive copper
wire.

The Overload Capacity chart, Figure A on page 4, gives an idea of time
vs current though it considers both wire and contact brush heating.
http://www.instrumentsgroup.co.za/in...stat_specs.pdf

It suggests that 10AWG wire could safely handle 200A for about 2.5
seconds, if it had their Powerkote insulation. Figure C shows 90C as
the temperature limit.

I picked 10AWG as the largest size that's useful elsewhere later, such
as in a solar system. I have up to 4 AWG in my system, connecting the
batteries, but it's short and I can't justify buying a lot more of it
for a one-time project. Perhaps the cheaper CCA (copper-clad aluminum)
that isn't legal for building wiring could be used and then resold to
car stereo installers. Pure copper wire is OFC, oxygen-free copper.
https://www.amazon.com/InstallGear-G.../dp/B01MXRVIPD





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