Help needed - NEM socket and buffer gaps

[Will_J]

Hi folks! As some of you know, I currently have some plastic NEM sockets being tooled at the factory for use with future wagon kits, but these could also be retrofitted to other wagons if desired. I've been waiting for them for a long time but apparently there's now some movement on it.

In addition to this, I have been quietly developing a new coupling system that is compatible with NEM sockets (so would be suitable for N, 009 and TT120 with NEM 355 sockets factory fitted.) It is a tension lock style design which uses permanent magnets fixed between track sleepers to uncouple, and also has a latch delay function similar to DG or Spratt and Winkle couplings which makes for great shunting. It's just a lot simpler to build and install. First prototypes have worked very well, and once I've ironed out some minor kinks, I'll show them.

However, one problem I am having is that placement of NEM sockets relative to buffer beams and the gaps between buffers varies wildly between models and manufacturers. So if people were willing, what would be incredibly useful to me is if people could measure the distance between the front face of the NEM socket and the face of the buffer beam, and also the front of the socket to the buffer faces. It would be tremendous to have these measurements for a variety of locomotives and rolling stock if possible.

This will help me decide what lengths of shank I should include as options, so that these will fit nicely into a wide variety of existing models.

Many thanks, and I hope to show more soon!

Will.

[Steven B]

The NEM355 standard quotes 6mm from the front face of the pocket to the buffers.

What works practically will depend on close coupling mechanisms and minimum radius on the layout.

Looking forward to seeing what you produce - will it be any smaller/better than Dapol's Easi-shunts?

[Will_J]

The NEM355 standard quotes 6mm from the front face of the pocket to the buffers.

What works practically will depend on close coupling mechanisms and minimum radius on the layout.

Looking forward to seeing what you produce - will it be any smaller/better than Dapol's Easi-shunts?

Indeed! Adherence to that standard is....not universal, shall we say ! In terms of smaller and better, subjectively I would say that they are more discreet than Easishunts - those knuckles are quite noticeable on N gauge rolling stock. However they will be more visible than say DG couplings.

In terms of better, it depends what you want I suppose. I designed these to be really good for finescale shunting of NEM fitted stock, primarily. The fact that you only need a magnet at the entrance to a siding and can leave a wagon anywhere you like once you have passed the magnet is a feature I really like. It functions identically to Sprat and Winkle couplings in terms of movement, though the design of the catch is completely different, and pivots up not down. Here's an example of what shunting will look like and I have already tested this successfully on some N gauge wagons, though this video example uses OO Spratt & Winkles.

I terms of assembly, they are much easier than DG in that there is no soldering or need for exotic glues, but it's not "push in and go" like Rapidos or buckeyes.

Will.

[ntpntpntp]

I usually keep 3 different lengths of NEM shank Rapido couplings in my spares box.  The middle ones in this photo are Farish "standard", I forget where the others come from though I think the long shanks are Dapol (for the 67?)   5.75mm difference between shortest and longest.

[Southerngooner]

If your couplings are to be used for pushing stock along make sure there is some sort of pushing bar as on the DG/B&B. Without this you will get problems when pushing round reverse curves. What works in 4mm does not always work well in N. As someone who is a long term B&B user (over 200 made and in use.....) I wish you well, but it would need to be a really good product to make me want to change!

dAve

[Will_J]

If your couplings are to be used for pushing stock along make sure there is some sort of pushing bar as on the DG/B&B. Without this you will get problems when pushing round reverse curves. What works in 4mm does not always work well in N. As someone who is a long term B&B user (over 200 made and in use.....) I wish you well, but it would need to be a really good product to make me want to change!

dAve

That's a good tip and something I will be sure to test! These aren't really meant to poach DG/B&B users, hopefully they will be something that offers similar functionality to those without needing much assembly and having the convenience of NEM plugs. But they won't be as discreet overall - you can barely see DGs from what I've seen!

Will.

[Steven B]

I think the left hand one is Farish's short coupling - 379-402.

For DG fans, the 2mm Scale Association now make NEM Coupling shanks for use with the DG etched parts. Part number 2-113.


From the instructions:

Revolution, and a few items from other manufacturers like the Dapol Hymek are to NEM standards
• Most models, including most Farish and Dapol, have the pocket closer to the buffer faces, usually
4mm to 5mm.
• Some couplings are even closer to the buffers, about 3mm. These include some freight stock and
steam loco bogies and pony trucks.
• For any less than 4mm it is not possible to shorten the coupling enough. Either accept the larger
gap between stock or remove the NEM pocket and glue the coupling on directly.

[EtchedPixels]

When I made NEM bar couplings for permanently attaching stuff together I ended up with a 3D print tool that you could just tell the length you wanted this time, and for the Etched Pixels ones I ended up selling I think 3 lengths.

IMHO there's no correct answer, and sometimes you also end up with different lengths each end as one short/one medium is correct etc.

plus of course some couplers are body mounted and change distance on curves.

[Will_J]

Revolution, and a few items from other manufacturers like the Dapol Hymek are to NEM standards

So by this I assume it means exactly 6mm between the front of the socket at the buffer face? That's useful. I may well go with something like 4mm, 6mm, and 8mm shank options in the set to cover as wide as range of possibilities as I can. The will also use the same steel catch.

Will.

[Steven B]

See page 38 of the West Hill Wagon Works Hunt Couplings Guide.

Their three NEM pocket couplings measure out at 7.5mm, 6mm and 5.2mm from the front of the NEM socket to the outer face of the coupling.

I've yet to need to use the 7.5mm one.

Note the magnetic couplings do need at least one vehicle to have a close coupling mechanism (unless the pivoting coupling is used) - fixed NEM pockets and magnets tend not to go round curves particularly well! I'm guessing if you're going for a DG/B&B type coupling this wouldn't be an issue.

7mm, 6mm and 5mm might be good starting points?

I'm looking forward to seeing these couplings develop!

[Will_J]

7mm, 6mm and 5mm might be good starting points?

I'm looking forward to seeing these couplings develop!

Thanks Steve, my own investigations have since yielded similar measurements to test so it's good to have that corroborated!

These will have a side clasp a bit like Tillig couplers so should remain rigidly in line when pushed around corners - though what radii they will be happy with when pushed is anyone's guess and will come out in testing.

Will.

[Will_J]

Ok I have now finished the designs for this round of testing, thanks for your input everyone! I now have three shank lengths to test, and assuming that the NEM standard of 6mm from the front of the coupling socket to the mid point between the couplings is 6mm (it is often considerably shorter on actual models) you get:

Size: Short Midpoint from socket: 6mm Buffer gap: 0mm

Size: Medium Midpoint from socket: 7mm Buffer gap: 2mm

Size: Long Midpoint from socket: 8mm Buffer gap: 4mm

So in the case of a socket which is only 4mm from the buffers (2mm under standard) then you would get a 4mm buffer gap using the short coupler. I hope that makes sense. So you should be able to get the right buffer distance for your layout curve radii for looks and reliable operation across a wide range of different rolling stock.

These will also work for 009 and TT120 using the same sizes which is handy!

When I get the second catch versions back from the etchers I will test it and update this.

Will.