neodymium magnets

Do you make pole pieces for them? Care to post any details on size, part numbers, location, etc?

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!

Dan Mitchell ==========

Kelly wrote:

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?

Composition: NdFeB Shape: Disc 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

Hi- 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.

David

Kelly wrote:

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.

Dan Mitchell ==========

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