DG Coupling dimensions/drawings?

[Will_J]

Hi all, I have decided that I need to create my own coupling design. I really like how DG couplings work and want my couplings to be compatible with them, however they are very fiddly to assemble and perhaps beyond the newbie modeller (gotta think as a product designer.)

I am going to design a resin printed version onto which it is easy to glue an etched phosphor bronze hoop part, and an etched mild steel dropper arm. These will have a flat mounting plate to 2mm finescale wagon standards, as well as an option for a NEM shank so that NEM wagons can be very easily retrofitted with the new couplings.

I have a few useful dimensions like the required assembled height of the buffing plate from the rail, and I believe the hoops are 5 x 3.5mm.

If I knew the precise dimensions of the etched mounting plate from this image, I could make sure my couplings are fully DG compatible.

Can anyone help?

[PLD]

Have you also looked at the B&B couplings?
They work on exactly the same principles as DGs, but the loop comes preformed as an etched brass part, and a much better pivot arrangement for the latch making them much easier to assemble.

While DGs seem to be the default for 2mm finescale, B&Bs seem more commonly used for N Gauge and a fair number of 009 modellers.

[ChrisGH]

Hi Will J,
You will struggle to get the fineness of the printing needed to make your version of DGs.The small tongue used for loose shunting that is used to hold the coupling loop away from the hook would be a nightmare to get right as it has to pivot freely on and off the top of the coupling hook.It is difficult enough as an etch to get right. You might get away with the buffer beam as is but the coupling hook is so fine that I don't think you would be able achieve reliable coupling.
The 2mm association already have NEM conversion shafts available but you need membership to buy.
BBs are no easier to set up even though they have the loop as a complete loop/pivot assembly as they have 2 sets of pivot holes which all have to be aligned simultaneously with the pins.
I have converted most of my rolling stock (Farish, 2mm Association and Peco) to DGs without any problems
Regards Chris

[Will_J]

Thanks both! Yes I have seen the B&B couplings and they look good too. Bear in mind this isn't just for my personal use - I'm not squeamish about solder and fine gauge wire - but I'm trying to see if I can come up with a solution that is as functional as DG/B&B, but has more user friendly assembly that can be done with standard plastic/resin modelling tools/adhesives. Something that could be injection moulded should the demand arise, with a few manageable etched parts. Something that a modeller of average skill could assemble reliably with minimal fuss.

The compromise is likely to be that they won't be as visually discreet as the other designs, but they'll be a lot better operationally than the standard Rapido Easy Lift Couplers my kits are supplied with.

It may not be possible, but worth the investigation .

[Southerngooner]

I'm a long time user of B&Bs and the attraction for me was the lack of soldering, which is needed with DGs. Apart from wrapping the iron wire round the dropper, which can be a bit fiddly, they are fairly easy to assemble.
 
Anything you design will still need something hanging down that is magnetic in order to make it work. I do wonder if a resin base would be strong enough to resist rotation in the arm piece which will surely be needed, given that it will need to be fairly thin and quite small.

Give it a go by all means.....even though I'm not sure what you will get out of it that would be better or easier than B&Bs.


Dave

[Will_J]

I do wonder if a resin base would be strong enough to resist rotation in the arm piece which will surely be needed, given that it will need to be fairly thin and quite small.

Thanks Dave I can see why you like them! "Resin" is as broad a term as "plastic" and material properties vary a great deal, I have a few resins in my cabinet that I am almost certain would be well suited.

However I am thinking that an etched phosbronze hoop would be the way to go, but glued to resin/plastic parts in the coupling body for a solderless, bendless, snap together design.

But I think I have enough info to go on in order to prototype something now. Many thanks all, additional input would still be welcomed .

Will.

[njee20]

By all means Will if you want to chase your own design then crack on, but I don't believe the barrier to using B&B/DG couplings is the difficulty assembling them. By extension, I don't believe that were an 'easy build' version they'd suddenly leap in popularity.

99% of the hobby have no interest in building 'stuff', whatever that may be, and I'd be very confident that virtually all of the 1% are not put off by the effort involved in the existing options.

[Yet_Another]

99% of the hobby have no interest in building 'stuff', whatever that may be, and I'd be very confident that virtually all of the 1% are not put off by the effort involved in the existing options.

That analysis is probably right, but there's a bigger Venn diagram that has people who can't be doing with faffing around with hundreds of tiny etches, but want a better coupling, of which I'm one.

[Platy767]

@Will_J

My DG etch is very old, but I had a measure for you. I measured the squarish bit width and length using a Mitutoyo Digital caliper on inches.

I measured the mounting pad as 0.1980" wide and 0.2205" long



Best wishes with the project.

Many years ago I had a go with B&B, DG, MBM couplers, but decided on the Kadee, now Micro Trains, couplers, but the draft box is quite thick and the 1023 coupler I use as by default is long.

Mark

[Will_J]

By all means Will if you want to chase your own design then crack on, but I don't believe the barrier to using B&B/DG couplings is the difficulty assembling them. By extension, I don't believe that were an 'easy build' version they'd suddenly leap in popularity.

99% of the hobby have no interest in building 'stuff', whatever that may be, and I'd be very confident that virtually all of the 1% are not put off by the effort involved in the existing options.

I'd say you're spot on with that analysis. I think 99% may be a little high, but I totally agree that the kit market in railways is very small compared to the market for RTR. I'm not really aiming to create a "disruptive" product here because those who already use B&B or DG will likely stick with them. However I think that having an "advanced" coupling system of my own design and manufacture (therefore not having to rely on other suppliers/stock) that is within the reach of anyone modelling my wagons would be a nice addition to the experience of building my kits, and is not a big investment of time or cost. So it's more of a convenient enhancement to the main products than a standalone product intended to go head to head with others. A dab of product polish, if you will. What is important is that they are compatible with those other couplings, at least within reason and assuming the standards have been followed.

That analysis is probably right, but there's a bigger Venn diagram that has people who can't be doing with faffing around with hundreds of tiny etches, but want a better coupling, of which I'm one.

I suspect that this is indeed the case. It's not a big group, but I think one worth considering. I manufacture both resin and plastic kits (aircraft) and more advanced modellers sometimes have a hard time believing that when it comes to model products, convenience and familiarity aren't just king and queen - they are Supreme Intergalactic God Emperor. When you make something convenient and appealing to beginners and intermediates, you barely even have to market it. It flies off shelves, while your beautiful museum quality etched brass hand cast resin kits languish in the warehouse for years. It's nuts, and kind of sad in a way.

Long story but someone who developed hobby products at Games Workshop to support the Warhammer ranges once told me that the modelling hobby is like a funnel with lots of holes holes in it - the top is full of newbies with some cash but limited skill and patience, and the bottom is a handful of world class experts who will do anything to realise and finance their dream. People fall out of it as they move down the funnel, and in greater numbers the more inconvenience and unfamiliarity they encounter. So his job was to create products (like the excellent range of contrast paints and tools) that helped the newbies get a good result early on to keep them in the "funnel" where they might fall out of it sooner if they faced more challenge without those helpful products. Games Workshop don't make products for the bottom of the funnel, because those guys are so advanced that there are not many of them and they're making their own products anyway. Though their subsidiary Forgeworld caters more to that. I see people soldering their own DG couplings as that kind of hobbyists.

I'm sort of looking at the middle of that funnel with my stuff when it comes to railways. Though if the business grows well, I will certainly turn my gaze upwards too, if I can!   

@Will_J

My DG etch is very old, but I had a measure for you. I measured the squarish bit width and length using a Mitutoyo Digital caliper on inches.

I measured the mounting pad as 0.1980" wide and 0.2205" long



Best wishes with the project.

Many years ago I had a go with B&B, DG, MBM couplers, but decided on the Kadee, now Micro Trains, couplers, but the draft box is quite thick and the 1023 coupler I use as by default is long.

Mark

Wonderful, thank you so much Mark!

Will.