Should work, but be careful ... an uncoupling magnet CAN be too strong!
Even the bigger Kadee undertrack magnets will pull a free rolling car
from more than an inch away if it has ANY iron or steel in it's
construction (axles, screws, weights, detail parts, etc.). This is
enough to 'bunch slack' and cause false uncouplings. The stronger your
magnets, the more 'religious' you have to be in de-magnetizing your
cars. I've seen truly free rolling cars 'pulled' enough to cause a false
uncoupling from JUST the Kadee trip pin!
A neodymium 'super magnet' may well be able to uncouple cars from
beneath the typical benchwork surface. Thus removing the need to cut
pockets into the roadbed of existing (perhaps already ballasted) track.
BUT, the further away the magnet is placed, the WIDER it's range of
influence. A 'super magnet a couple inches below the track could be
causing uncouplings over an area six inches long or more. It might well
be hard to control the 'action'.
And, almost ALL locomotives have iron in their construction, not to
mention OTHER magnets (motor), and could have unpredictable interactions
with a big 'super magnet'. It's EASY to imagine a loco being STUCK to
the track and unable to move while crossing such a 'super magnet'
uncoupler. Heck, even a small super magnet can be too powerful for a
strong man to remove from a steel object.
Also, be careful with them ... they CAN be dangerous. They can 'snap'
onto an object with enough force to SEVERELY pinch you, and cut through
skin, causing substantial injury. Rapid 'super magnet' motion near
electronics can also cause damage to the circuit components. And keep
any magnetic media AWAY ... FAR away!
The types (sizes) changes all the time but the ones I have are similar
to #MAG-74, 0.2 x 0.4 x 0.105. I use a total of 4 magnets two on each side
of a piece of plastic about 40 thousands thick. Just make sure the polarity
is correct. ACC or epoxy the group together. These will fit under a couple
of ties (HO) or can be glued to the track before installation. Fill the
remaining hole with ballast and whatever you use for ballast glue. Take a
short piece of track and test first. Usually these magnets are so strong
it's impossible to put them together wrong. Mark the track, a little yellow
on the side of the rail is good. Unless the coupler is directly over the
magnet it won't uncouple.
Buy a few, test, and see what you think. At 25 cents in hundreds, that
a buck an uncoupler and I feel they are vastly superior to the Kadee units
of any design!
Do you think the 1/8" round x 1/8" long ones would work?
Coating: Gold Plate
Dimensions: 1/8" dia X 1/16" thick
Br max: 13,700 Gauss
Bh Max: 45 MGOe
It would be great to drill 2 1/8" holes between the ties
and glue them in place.
If not the 1/8" how about the 1/4" dia.
CAT# MAG-76 ?
Or glue these to the top of the ties CAT# MAG-82
I have tried a bunch of different ones. Unfortunately, I couldn't get
the smaller ones to work well -- but maybe I did not get the
configuration right. The 0.5" diameter by 0.2" work quite well in
pairs, on a slight angle.
If someone comes up with a sure-fire method, especially with the smaller
kind, let us know. It would be really nice to drill a couple of holes
and sink in the magnets.
You need to get a couple and test. The listing usually don't tell how
the polarity is. The center of the track needs to be the center line on the
magnet so that the pins will go to opposite rails.
The reason I use the center plastic piece is so each pin will go to the
nearest rail (thus uncoupling). As these magnets are very strong this force
needs to be more than the attraction force, otherwise they try and draw the
pin to the ties.
As I got these a long time ago I am thinking that the #72 (.35 x .28 x
.22) might work well also. These magnets come and go quickly at All
Electronic so the ones I experimented with I couldn't get again but I had
learned what I needed. So when a similar one was stocked I bought a bunch.
Actually, the magnet field just needs to be crosswise to the rails.
There is no 'center' in a magnet, just two poles of opposite polarity.
It's easier to understand if you take a look at the Kadee
electromagnetic uncoupler ... there's just ONE coil, forming ONE magnet,
with two pole pieces, one near each rail. NO 'center' pole piece. ANY
magnet with the field aligned crosswise of the rails will work, assuming
it's appropriately strong. You can even place two magnets with on each
side OUTSIDE the rails as long as their polarity is such as to create a
crosswise field between them. One of the commercial (Rix?) uncoupling
'sticks' use this technique, albeit with the two magnets closer together
than the rails.
The (non magnetic) iron Kadee trip pins will try to align to the
magnetic field, thus twisting them outward from the center, and rotating
the coupler knuckles 'open' in the process. Ever notice that the Kadee
trip pins are not parallel to the rails when at rest? They have SOME
sidewards angle built in, so that they will have a favored direction to
twist toward in aligning with the magnetic field. Since the cars are
facing one another, the pin on the right hand car points to the near
rail, and the one on the left hand car points to the far rail. When they
pas over a magnet each coupler experiences a force that tries to deflect
the trip pin further in the direction it's already facing.
This is one reason that the Kadee couplers do NOT work well on curves.
Even if you offset the magnet, one car will have it's trip pin
positioned more nearly parallel to the rails in a curve ... thus it gets
easily 'confused' on which way to deflect. It may deflect the WRONG way,
or just sit there without opening the knuckle at all ... making
uncoupling difficult at best.
> You need to get a couple and test. The listing usually don't tell how
> the polarity is. The center of the track needs to be the center line on the
> magnet so that the pins will go to opposite rails.
> The reason I use the center plastic piece is so each pin will go to the
> nearest rail (thus uncoupling). As these magnets are very strong this force
> needs to be more than the attraction force, otherwise they try and draw the
> pin to the ties.
> As I got these a long time ago I am thinking that the #72 (.35 x .28 x
> .22) might work well also. These magnets come and go quickly at All
> Electronic so the ones I experimented with I couldn't get again but I had
> learned what I needed. So when a similar one was stocked I bought a bunch.