Magnetic couplers


7

747flier

Well-Known Member
The kids Brio trains use magnets to couple the trains together. I found a source for very small rare earth magnets which might be able to be used for constructing more scale sized couplers. The shank protruding from the draft box could be mostly printed with a steel insert attached to the magnet, residing in the draft box? Anybody know if this has been tried?

Tom
 
Haha!!! I wondered, because you are already making trucks, if you were gonna go here: To actual couplers. IMO these are a real problem in N-scale, and I do think the Kadee design could be improved upon. Biggest problem in N is the spring effect. N cars are light enough that, even in mid train there is the ping-pong effect. Kinda kills the realism, IMO.

Of course Kadee does now offer the realistic couplers, but, and while they are much more to scale, they do so at the cost of having to lift one up off the other to switch cars. Unless I'm greatly mistaken (always possible), they can't be uncoupled using a vertical pick.

I see several problems. Travel/slop is just too big, which gives the spring room to...yo-yo. The spring itself might be removed in favor of something which compresses, but which does not spring back so easily. Sort of like a micro-miniature version of a "memory foam" cushion. Compresses easily and quickly, but springs back slowly....

And, last, the entire problem of the way couplers are manufactured when injection molded. There is, because the two halves of the mold must be separated and the part ejected...there is a parting line (generally right down the horizontal centerline of each coupler because the two halves separate vertically)...and mold "draft angle," which is needed to get the part loose enough to eject it. So what you have are two couplers basically trying uncouple with each other vertically, simply because of the necessities of the injection mold manufacturing process, and the design.

But what if you could make each knuckle concave, to help lock them together, or even just truly flat (sans any molded draft) instead? What if?

I'll bet the parts might be 3D modelable when printed, and even though such parts might not be machinable on lathes or milling machines, no matter the cost. I think some things are printable, but can't be machined without great cost, or even at all. Things like "herringbone gears."

See those gears @11:15.
 
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Interesting video!

I'm not sure that for myself metal works such as he was doing is a good way to go. For the idea under consideration, my current idea is to use a ferrous metal as an extension off of a main magnet, about the size of a coupler draft box. Such magnets have a hold force more than the typical car weight. The ferrous extension would be to make something extending as a magnetic touch point and perhaps some printed add-on would be to make it look more coupler like.

With the HON3 cars there is enough weight that I think this could be made to work. The current weighted flat cars I am building weigh in a 2.2 OZ, most of the weight being a 1/8 x 1/2 x 2 3/4 inch steel bar stock.
 
No, and if I didn't make it clear, it's not at all necessary to print or mold in metal. I was simply trying there to illustrate the "herringbone gear" concept and how it's difficult (possible, but still difficult) to manufacture...but quite possibly easy if 3D modeling.

Let me narrow that down a bit: via SLA 3D modeling, rather than filament build modeling.

That said, and even in N-scale, what we are discussing (I apologize for yanking your thread sideways) are gears something akin to watchmaking gears. Meaning: You could achieve the same centering effect by adding sides to the gears--herringbone is not necessary.

However...the herringbone gear concept DOES show--even if roughly--the sort of "self correcting and automatically meshing" thing I was alluding to above: Gears (or couplers) which tend to want to fit together and hold together, rather than try to shed one another because of the design (and the rest).

Herringbone gears are more easily replaced in N-scale, and maybe in HOn3 too, by gears with "sides," which keep each meshed to the other. Watchmakers type gears....

As far as your coupler ideas go (more power to you!) I also wonder if you couldn't snap the couplers open or closed using a micro-mini solenoid, which might bring your magnet into play. Which might bring it close enough to do the deed, etc. To uncouple the two cars (or maybe to couple them...or both).

If nothing else you might prototype your idea. Florist's wire (soft) is, as far as I can tell, pretty much iron wire. Near ultimate material as far as magnetism goes.
 
If I have time to pursue this (Summer is great for other things) I'll start out with the KISS principle.

The biggest issue I see is the magnetic poles. There is some way around this, just don't know what it is so far, as cars would have to always be oriented N to South magnetic poles or they would repel. Same thing if a magnet was used on one end and just a ferrous metal on the other. I used this method for attaching secondary mounts to my 1:192 USS Alaska, allowing them to rotate and be removable.

Cheers: Tom
 
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747flier said:
If I have time to pursue this (Summer is great for other things) I'll start out with the KISS principle.

The biggest issue I see is the magnetic poles. There is some way around this, just don't know what it is so far, as cars would have to always be oriented N to South magnetic poles or they would repel. Same thing if a magnet was used on one end and just a ferrous metal on the other. I used this method for attaching secondary mounts to my 1:192 USS Alaska, allowing them to rotate and be removable.

Cheers: Tom
Click to expand...
I understand it works by using a magnetic coupling on one car which attaches to a metal plate in the following car's coupling. But I may have got it completely wrong.
 
A possible solution? A gent was thinking of making a pocket and link coupler. Something along this line, very simple, a ferrous metal piece on the end of each draft box and a magnetic link. There are inexpensive and strong enough magnets to provide this link. 2.5 x 3 mm cylinders. This would avoid the necessity of only hooking up one end of the car every time.
 
Current thoughts on this is (1) have a small magnet located in each coupler pocket and use a short appropriately shaped or covered link to join both cars. I think this will work, not needing anything special for the link. (2) use one of the small 2.5 x 3 mm cylinder magnets as a link with each car just having a slightly rounded metal end in each coupler pocket. These small magnets apparently have enough gauss to actually suspend a typical narrow gauge car.
 
A quick experiment eliminated #1 as the magnets will have N-S poles, which would allow cars to only be coupled one direction to each other. A large limitation! Wrong way, the cars repel. So I think a magnet should orient itself to attract to a ferrous non magnetized and make a satisfactory link. However there is there danger that the non magnetized parts might become magnetized?
 
Thank you for the info. It would appear that magnet to magnet that the cars could only be coupled one direction, perhaps a satisfactory arrangement, perhaps not. Those look like some of the small cubic magnets available, about 2.5 mm or so.
 
I did this a long time ago when i bought a train while on a school trip in Italy and when i got home it was not great with my hornby couplers and somehow snapped off, my dad had the idea of using a couple of magnets and it worked pretty well.. Not sure about realism and all that, but it certainly made the carriages follow the loco :confused:
 
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What about these neyodyne balls?
They should also give a nice articulation being round. Combined with what someone above said with the 3mm cylinders you could have something like this with a bit of grease on them:
🚃=O=🚃
(but obviously a lot smaller😆)

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