degaussing for compass

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

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.

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.

(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" 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...

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?
|

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.

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.
|

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.