degaussing for compass

[karl gruber[_1_]]

SOMEWHERE on the net I've seen somebody who rents out equipment to degauss
the area around where the compass goes.

In Cessna 180/185s the compass rests between a steel "V" brace and this
sometimes gets a magnetic set, or something. Does anyone remember who rents
out that equipment?

Karl
"Curator" N185KG

[Christopher Campbell[_1_]]

On Fri, 8 Dec 2006 09:32:32 -0800, karl gruber wrote
(in article >):

> SOMEWHERE on the net I've seen somebody who rents out equipment to degauss
> the area around where the compass goes.
>
> In Cessna 180/185s the compass rests between a steel "V" brace and this
> sometimes gets a magnetic set, or something. Does anyone remember who rents
> out that equipment?

Didn't Mike Pickett know someone who has something like that?

[rq3]

Sacramento Sky Ranch used to rent a degausser, or you can buy one at
Radio Shack (it's called a bulk tape eraser).

karl gruber wrote:
> SOMEWHERE on the net I've seen somebody who rents out equipment to degauss
> the area around where the compass goes.
>
> In Cessna 180/185s the compass rests between a steel "V" brace and this
> sometimes gets a magnetic set, or something. Does anyone remember who rents
> out that equipment?
>
> Karl
> "Curator" N185KG
>
>

[Neil Gould]

Recently, rq3 > posted:

> Sacramento Sky Ranch used to rent a degausser, or you can buy one at
> Radio Shack (it's called a bulk tape eraser).
>
> karl gruber wrote:
>> SOMEWHERE on the net I've seen somebody who rents out equipment to
>> degauss the area around where the compass goes.
>>
>> In Cessna 180/185s the compass rests between a steel "V" brace and
>> this sometimes gets a magnetic set, or something. Does anyone
>> remember who rents out that equipment?
>>

Be aware that a "degausser" can also be a "gausser", and magnetize the
object instead. It may be a more tricky task than it appears, since to
degauss the object one has to apply exactly the amount of magnetism of
opposite polarity. When erasing tapes, this isn't much of an issue,
because the recording process will overcome the relatively weak magnetism.
I'm not so sure about successfully degaussing steel bars near a compass,
and certainly not while they're installed.

Neil

[[email protected]]

karl gruber > wrote:
> SOMEWHERE on the net I've seen somebody who rents out equipment to degauss
> the area around where the compass goes.

http://www.repairfaq.org/sam/crtfaq.htm#crtmdg might be of interest,
even though it is talking about color CRTs and not the metalwork around
a compass.

Matt Roberds

[john smith]

Degaussing an airframe is not quite the same as degaussing a magnetic
tape or CRT.
I have "heard" of people doing it with a 110VAC line and a 100W light
bulb for a load.

[nrp]

It may be a more tricky task than it appears, since to
> degauss the object one has to apply exactly?

Degaussers work from line power by generating a strong 60 Hz
alternating flux which is slowly decreased in intensity by removing the
degausser coil away from the subject. I'd remove the compass and any
electronics first though for that reason.

I'd think a strong or larger degausser could be temporarily made from a
500 ft coil of three conductor (plus ground) # 14 romex wiring cable.
The ends should be connected to make a 2000 ft coil, and the whole mess
tied together with tie wraps. As an alternate the whole mess could be
made with 3 conductor extension cords. & a suicide plug/socket
arrangement.

Has anyone ever tried something like this?

> Neil

[nrp]

On Dec 8, 12:59 pm, "Neil Gould" > wrote:
> Recently, rq3 > posted:
>
> > Sacramento Sky Ranch used to rent a degausser, or you can buy one at
> > Radio Shack (it's called a bulk tape eraser).
>
It may be a more tricky task than it appears, since to
> degauss the object one has to apply exactly?

Degaussers work from line power by generating a strong 60 Hz
alternating flux which is slowly decreased in intensity by removing the
degausser coil away from the subject. I'd remove the compass and any
electronics first though for that reason.

I'd think a strong or larger degausser could be temporarily made from a
500 ft coil of three conductor (plus ground) # 14 romex wiring cable.
The ends should be connected to make a 2000 ft coil, and the whole mess
tied together with tie wraps. As an alternate the whole mess could be
made with 3 conductor extension cords. & a suicide plug/socket
arrangement.

Has anyone ever tried something like this?

> Neil

[nrp]

It may be a more tricky task than it appears, since to
> degauss the object one has to apply exactly?

Degaussers work from line power by generating a strong 60 Hz
alternating flux which is slowly decreased in intensity by removing the
degausser coil away from the subject. I'd remove the compass and any
electronics first though for that reason.

I'd think a strong or larger degausser could be temporarily made from a
500 ft coil of three conductor (plus ground) # 14 romex wiring cable.
The ends should be connected to make a 2000 ft coil, and the whole mess
tied together with tie wraps. As an alternate the whole mess could be
made with 3 conductor extension cords. & a suicide plug/socket
arrangement.

Has anyone ever tried something like this?

> Neil

[Jose[_1_]]

> ...I'd remove the compass and any
> electronics first though for that reason.
>
> I'd think a strong or larger degausser could be temporarily made...

Is degaussing an airplane considered by the FAA as something that an
owner/pilot could do?

Jose
--
"There are 3 secrets to the perfect landing. Unfortunately, nobody knows
what they are." - (mike).
for Email, make the obvious change in the address.

[Neil Gould]

Recently, nrp > posted:

> It may be a more tricky task than it appears, since to
>> degauss the object one has to apply exactly?
>
> Degaussers work from line power by generating a strong 60 Hz
> alternating flux which is slowly decreased in intensity by removing
> the degausser coil away from the subject.
>
My over-generalization was in response to the typical use of a magnetic
tape degausser where the size of the coil is much larger than the item
being degaussed and the purpose is only to randomize the magnetic
alignment of the oxide particles. In that use, residual magnetism isn't
critical, but I don't think it would be the same for magnetized bars (the
braces) that are much *larger* than the coil.

> I'd remove the compass and
> any electronics first though for that reason.
>
> I'd think a strong or larger degausser could be temporarily made from
> a 500 ft coil of three conductor (plus ground) # 14 romex wiring
> cable. The ends should be connected to make a 2000 ft coil, and the
> whole mess tied together with tie wraps. As an alternate the whole
> mess could be made with 3 conductor extension cords. & a suicide
> plug/socket arrangement.
>
> Has anyone ever tried something like this?
>
Well... I still think it would be better to remove the braces from the
plane first. Using that size coil in-situ sounds risky.

Neil

[Jim Macklin]

AC 43.13-1 5-28


a. Demagnetization. Demagnetize between

successive magnetization of the same

part, to allow finding defects in all directions,

and whenever the residual magnetism interferes

with the interpretation of the indications.

Also, demagnetize all parts and materials after

completion of magnetic particle examination.

Test all parts at several locations and parts for

residual magnetism of complex configuration

at all significant changes in geometry. Repeat

demagnetization if there is any appreciable deflection

of the field indicator needle.

(1) AC method. Hold the part in the

AC demagnetizing coils and then move the

part slowly and steadily through the coils and

approximately 3 to 4 feet past the coils. Repeat

this process until the part loses its residual

magnetism. Rotate and tumble parts of complex

configuration as they are passed through

the coils.

(2) DC method. Place the part in the

same relative position as when magnetized and

apply reversing DC current. Gradually reduce

the current to zero and repeat the process until

the residual magnetic field is depleted.





You can make a loop of heavy insulated wire

"john smith" > wrote in message
...
| Degaussing an airframe is not quite the same as degaussing
a magnetic
| tape or CRT.
| I have "heard" of people doing it with a 110VAC line and a
100W light
| bulb for a load.

[Jim Macklin]

No
"Jose" > wrote in message
...
|> ...I'd remove the compass and any
| > electronics first though for that reason.
| >
| > I'd think a strong or larger degausser could be
temporarily made...
|
| Is degaussing an airplane considered by the FAA as
something that an
| owner/pilot could do?
|
| Jose
| --
| "There are 3 secrets to the perfect landing.
Unfortunately, nobody knows
| what they are." - (mike).
| for Email, make the obvious change in the address.

[nrp]

>
> (2) DC method. Place the part in the
>
> same relative position as when magnetized and
>
> apply reversing DC current.

What's a reversing DC current?

[Blueskies]

"nrp" > wrote in message ups.com...
:
: >
: > (2) DC method. Place the part in the
: >
: > same relative position as when magnetized and
: >
: > apply reversing DC current.
:
: What's a reversing DC current?
:

Just opposite polarity...

[Jim Macklin]

opposite polarity, switch direction manually. Use less
current (amps) with each cycle. There are machines that do
this automatically, but you can rig up something to do it
from odd bits and pieces.



"nrp" > wrote in message
ups.com...
|
| >
| > (2) DC method. Place the part in the
| >
| > same relative position as when magnetized and
| >
| > apply reversing DC current.
|
| What's a reversing DC current?
|

[nrp]

> opposite polarity, switch direction manually. Use less
> current (amps) with each cycle. There are machines that do
> this automatically, but you can rig up something to do it
> from odd bits and pieces.
There are machines that do
this automatically,

Isn't this the 60 Hz line? Just withdrawing the coil will fade the
cyclic magnetic flux.

BTW I had in mind a several ft diameter for the #14 wire concept, so
that a steel tube fuselage could be degaussed.

[Jim Macklin]

There are direct current machines for doing magnetic
particle inspection [MagnaFlux] and these machine do have a
built in degaussing procedure with DC current.

Yes, a large coil with AC can be used to degauss by
withdrawing the coil to several feet. Putting a tool or
tube in the AC field and switching OFF will magnetize
because the induced field is cut suddenly.



"nrp" > wrote in message
oups.com...
|
| > opposite polarity, switch direction manually. Use less
| > current (amps) with each cycle. There are machines that
do
| > this automatically, but you can rig up something to do
it
| > from odd bits and pieces.
| There are machines that do
| this automatically,
|
| Isn't this the 60 Hz line? Just withdrawing the coil will
fade the
| cyclic magnetic flux.
|
| BTW I had in mind a several ft diameter for the #14 wire
concept, so
| that a steel tube fuselage could be degaussed.
|

[RST Engineering]

That works ... sort of. How much magnetism (if any) you get, and of which
polarity is a function of where in the waveform the coil is when you switch
the current off.

Jim


>
> Yes, a large coil with AC can be used to degauss by
> withdrawing the coil to several feet. Putting a tool or
> tube in the AC field and switching OFF will magnetize
> because the induced field is cut suddenly.