Magnetic couplings

[Peter Richardson]

I have been experimenting with magnetic couplings but have hit the buffers in trying to do things on a budget! I bought a set of Dapol couplings and magnet and worked v well on trial section until one day it stopped working and I finally worked out the spring had popped out of the coupling and was nowhere to be seen. Thankfully spare springs are cheap, although I've still to take on the challenge of refitting this tiny component.

My next attempt was inspired by an article, I think was in a 009 News at some stage over the past year. I cannot locate it so if anyone knows the edition, please let me know. I drilled a tiny hole through the coupling and inserted a staple which I then bent round so it would stay in place (see photo). I ordered a set of tiny (3x2mm) neodymium magnets - very powerful but much cheaper than the Dapol bar ones and they fit between 009 sleepers so easy to fit/retrofit. The magnets draw the coupling down but no matter how I configure them, I can't get them to raise the coupling.

Any ideas or reference back to that article works be greatly appreciated! Otherwise, the more expensive Dapol option will have to be adopted if the financial controller gives the green light😂

[Retiarius]

I think you need the staple to be bent behind the pivot, not in front so that you force an upward rotation.

[Peter Richardson]

Many thanks for the advice and clear diagrams. I will give this a go!

Best wishes
Peter

[Graeme Dunbar]

You say you used two tiny Neodymium magnets. Many actuating magnets are physically larger, but not necessarily stronger. Older pre-Neodymium ones are almost certainly weaker.

You might try experimenting with different magnets or a combination of magnets and iron pole pieces. It may be more effective to use larger but weaker magnets to spread the field over a larger volume or use the smaller intense magnets and pole pieces to do the same. The iron actuating arms on the couplings forms part of the 'magnetic circuit' with magnets and will try to align with the magnetic field much like iron filings in a magnet experiment or demonstration.

If you are restricted to placing magnets between track that is already laid then it may take some experimentation with the positions and orientation of the magnets to get the North and South poles in the right alignment for the most reliable operation.

[Stephen Rainsbury]

My next attempt was inspired by an article, I think was in a 009 News at some stage over the past year. I cannot locate it so if anyone knows the edition, please let me know.

Could it be March 2016 page 17?

[Robin Webster]

Just for my education. Can a Microtrain magnet not work in place of the Greenwich type.

[Graeme Dunbar]

I get the impression Microtrains magnets have the field running side to side across the track because they have to pull the actuating arms sideways. (N pole by one rail and S pole by the other.)

I think I've seen an electromagnet version where the pole pieces were visible running parallel to the rails.

With Greenwich type couplings the field is better running N-S lengthways along the line of the track so the two iron legs on the couplings make two  vertical sides of a broken square with the magnet being the lower horizonal side of the square and the fourth upper horizontal side being 'air'.


Edit: found a Microtrains uncoupler video:
https://www.youtube.com/watch?v=GOuFtr8Eg1o

[Robin Webster]

I see, thanks for information.

[Julian Evison]

I believe Graeme is right. The metal 'whiskers' under a Microtrains coupler need to be drawn to the side in order to work, not down. The magnetic field therfore needs to be oriented side to side across the track, not perpendicular to it which you need for auto-uncoupling Greenwich couplings (and many other types of couplings).

Julian

[Peter Richardson]

Thanks for these responses, a few ideas to try out!

Will put up a post to let you know how I get on.

Best wishes
Peter

[Peter Richardson]

Following the advice provided, I am pleased to report that I have working couplings! I used the diagram provided to shape the paper clip and it worked a treat.

In order to be able to uncouple regardless of which way stock is facing, I have a magnet placed to the left and another one placed to the right.

I now have to start placing the magnets where required around the layout and adapt more couplings.  This is a case of drilling out a very small hole in the couplings to insert the staple which once cut and bent into shape can be glued in place.

While the couplings may not look as realistic as the Dapol ones, the total cost of this approach is about £3 (magnets) whereas the Dapol couplings and magnets would have been a lot more.

Many thanks for everyone's help with this, v much appreciated!

Sorry photos are a little blurd.