I have been experimenting with uncoupling (Peco wagons and their magnetic lift arm add-ons).
After some abortive attempts {with various domestic magnets ( including some liberated from 'ear buds', which googling suggested were strong ! nope !! just ferrite I think ) }

So I ordered up some super strong N52 neos from the usual bay,
10mm dia and 5mm long and inserted under the track base
Gosh ! well strong, no need to exactly align the coupling, the pull on the, steel(?) weight in the wagon was good enough to cause the coupling to reside over the right position and the arm lifted correctly.

But now I am worried that if I inadvertently run the loco over such a strong magnet will I do damage to the loco ? or is it shielded by its own magnetic circuit  ??

So I think maybe I need to either moderate the magnet (smaller? N32 ?) or retract/insert it only when required.

Thoughts please ! ?

An interesting question, especially as somewhere in 'that safe place' I have some of the Peco magnets and lift arms, so I look forward to hearing views of the collective, too

was fed into an MRI scanner yesterday pm and spent the next little while "contemplating" strong magnets - trying to focus on just these uncoupling issues on model railways rather than anything else being uncoupled!

why? .............. well, if you've had the experience, you'll know it's preceded by a pretty rigorous quizzing as to what bits of metal might be lodged (deliberately or not) around the body!!!!!!!!!!!

thank goodness models can carry your mind away from reality!

Adrian - survivor!

The magnets around the motors should be OK, I suspect they would have to be in physical contact with the magnets for some time. Modern motors are in a metal can, so have a bit of protection there as well.

Quote from: Only Me on June 03, 2015, 02:34:28 PM
plus using the rare earth magnets you need to mount a mm or two lower than the base board otherwise your wagons will do wheelies

Not so much a problem for Peco lift arms (as for Dapol Easi-Shunts) as the pull comes generally from under or behind the leading axle rather than in front of it.

Cheers Jon 

Not hijacking, I think?  Related but not couplings.

I strapped a Neodymium magnet to a flat wagon to collect stray pins, bits of metal etc.

On a corner the train was suddenly derailed and the wagon was left hanging on the wall attached to a steel screw head!

Good thing I have Titanium knee joints!

Peter.

Quote from: Malc on June 03, 2015, 11:05:09 AM
The magnets around the motors should be OK, I suspect they would have to be in physical contact with the magnets for some time. Modern motors are in a metal can, so have a bit of protection there as well.

Thanks Malc, yes those were the sort of things I was wondering about.

Quote from: Only Me on June 03, 2015, 02:34:28 PM
otherwise your wagons will do wheelies

You mean like this ! 
It does not happen every pass, but yes as you say, a bit more distance is needed.

Quote from: newportnobby on June 03, 2015, 10:06:21 AM
as somewhere in 'that safe place' I have some of the Peco magnets

I hope that is not the same 'safe place' that you keep your credit cards in !!!! 

Quote from: MalcolmAL on June 03, 2015, 07:35:33 PM

I hope that is not the same 'safe place' that you keep your credit cards in !!!! 

Funny you should say that, Malcolm

Quote from: petercharlesfagg on June 03, 2015, 06:12:56 PM
I strapped a Neodymium magnet to a flat wagon to collect stray pins, bits of metal etc.

hope I'm not teaching eggs but do you know the trick of enclosing the magnet in a polybag when sweeping for magnetic bits ? makes removing them much less tedious

Quote
Good thing I have Titanium knee joints!

trust nothing these days, yer canna trust the description no more.
EG. I heard that some graphite was diamagnetic (and a cheap source was pencil leads) and thus could be levitated above a strong magnet (=neo) combo, so I built my array of magnets and robbed a few chips from a pencil , , , nope ! didnt levitate.
but what was more strange was that the chips were strongly attracted to the magnets, now graphite I thort was not supposed to be ferromagnetic

back to the drawingboard with apologies for the OT to the OP ( oh that was me ! )

Quote from: MalcolmAL on June 03, 2015, 11:13:26 PM

Quote from: petercharlesfagg on June 03, 2015, 06:12:56 PM
I strapped a Neodymium magnet to a flat wagon to collect stray pins, bits of metal etc.

hope I'm not teaching eggs but do you know the trick of enclosing the magnet in a polybag when sweeping for magnetic bits ? makes removing them much less tedious

Quote
Good thing I have Titanium knee joints!

trust nothing these days, yer canna trust the description no more.
EG. I heard that some graphite was diamagnetic (and a cheap source was pencil leads) and thus could be levitated above a strong magnet (=neo) combo, so I built my array of magnets and robbed a few chips from a pencil , , , nope ! didnt levitate.
but what was more strange was that the chips were strongly attracted to the magnets, now graphite I thort was not supposed to be ferromagnetic

back to the drawingboard with apologies for the OT to the OP ( oh that was me ! )

Thanks for the tip, I hadn't thought of that!  Subsequently I had a struggle removing the tiny bits of metal!

Quote from: MalcolmAL on June 03, 2015, 11:13:26 PM
but what was more strange was that the chips were strongly attracted to the magnets, now graphite I thort was not supposed to be ferromagnetic

back to the drawingboard with apologies for the OT to the OP ( oh that was me ! )

There is often iron impurities in commercial graphite. These are randomly distributed through the carbon lattice, so you do find some bits are attracted more than others. Was this the case?

Quote from: Malc on June 04, 2015, 06:50:22 PMso you do find some bits are attracted more than others. Was this the case?

Dont know is the simple answer !! I only took a few mm off the end of a pencil which I then accidentaly broke in two, both seem to react the same.
But you have stimulated my curiosity now and I feel a sacrificial whole pencil is in the offing, in the interests of science of course 

I came to that experiment via an interest in seismology and an american group did at one time experiment with levitated graphite rods as a sensor. They found that propelling pencil leads were a viable source - me not remembering where my propelling pencil was last seen , , ,
ah, ding, but my Thornton instrument set had pencil leads for the compass etc. , if only I could remember where that was put , , ,
I think a visit to a local stationers may be needed, do they still exist ? ! Do propelling pencils still exist ?

BTW how did you come to know that about iron impurities in graphite ? Have you ploughed this furrow already 

Some quick Googling on my part, plus something in the back of my mind about arc lights which prompted the search.