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Author Topic: New coupler development (was Coupling survey)  (Read 30099 times)

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Offline belstone

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Re: Coupling survey
« Reply #120 on: September 05, 2014, 10:20:03 pm »
The work you are putting into this is much appreciated, Richard.
OK, it's mainly for your own reward but potentially many of us could gain from it so......
 :thankyousign:


Not much reward I fear, apart from ending up with a coupler system that suits my particular obsession with steam-era branch lines.  I hate to think how many hours I have put into this now - I'd have to sell an awful lot of couplings to make it financially worthwhile. But this is just the sort of design and development challenge that I enjoy for its own sake.  Over the weekend I will try to build a few 'Mk2B' couplings with redesigned delay bar - a bit fiddly as I will have to solder brass wire to the hooks while they are still attached to the fret. Mk3 will be a one piece etching if I get that far.

One small development - I have been wondering how best to paint the couplings. I decided to try black permanent marker - 'borrowed' from the kitchen where it is normally used to mark the contents of freezer bags.  Result is not too shabby, and unlike paint it doesn't gum up the works:


Offline Jerry Howlett

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Re: Coupling survey
« Reply #121 on: September 07, 2014, 11:23:30 am »
If it was me the hillside around here would be covered in small pieces of plastic and metal crushed and scattered to the wind.

I know I am not alone in watching your progress on this with a bag full of hope that it all comes together (or apart) over the magnet  :sorrysign:  in the end.

Keep up the good work and the progress reports.

Jerry
Some days its just not worth gnawing through the straps.

Offline belstone

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Re: Coupling survey
« Reply #122 on: September 07, 2014, 09:54:15 pm »
Another weekend of fiddling has seen the design progress rapidly through Mk2B (short piece of bent piano wire glued to the shank to stop the loop dropping over the end of the delay bar) to Mk2C (longer loop with bent up end, as per the Mk1 to stop the ends of the loops locking together). I now have enough converted vehicles to start proper testing, but my past sins have caught up with me.

Some of the trackwork on 'Belstone' really is terrible.  I laid it in a tearing hurry, ballasted it in even more of a hurry and I now have wonky bits of track and stray ballast grains which always seem to cause the loco to stall just as the last wagon in the train passes over the magnet.

I have also found that coupling height is more important than I thought - you can get away with about 0.5mm mismatch but more than that and delayed uncoupling becomes a bit hit and miss. Of course if I had fitted the couplings properly there wouldn't be a height mismatch...

And I now really, really hate NEM pockets.  I have seen jellies that wobble less than a Farish NEM pocket insert.

Richard


Offline belstone

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Re: Coupling survey
« Reply #123 on: September 20, 2014, 08:43:35 am »
Slow progress due to family illness and work stuff, but I'm now onto Mk2D (end of loop bent up and back rather than up and forwards) and finally getting reasonable results with Peco short wheelbase wagons which were always going to be the hardest vehicles to get any kind of uncoupling system to work with, since they are so small, light and free-rolling. 

I spoke to my father about the problem.  He was modelling in N gauge before I was born (I'm 46) and has a very practical mind. "File the pinpoints off the axle ends" he said.  So I did, and now have just enough rolling resistance to allow reliable operation...

One other discovery - the metal used in Bachmann-Farish wagon axles varies.  Some of them are strongly attracted to magnets, others aren't.  I haven't yet worked out whether it is the newer axles that are non-magnetic or the older ones.

Offline belstone

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Re: Coupling survey
« Reply #124 on: September 29, 2014, 09:53:20 am »
Another weekend of fiddling and fettling, and I'm almost there.  I now have two locos, two coaches and ten wagons fitted with Mk2d couplings, and have reached the stage where if a coupling fails to work properly I can look at it, identify the reason and fix it.  I can now perform complex shunting operations. I even managed to get my J39 to run half decently by packing some extra weight into the boiler.

If a coupling doesn't work reliably it is usually down to incorrect height, magnetic dropper not bent back far enough, coupling bar slightly twisted, or the bar being slightly too long and fouling a buffer head.  All easily fixable.

So I have pretty much done what I set out to do - develop a simple, robust and cheap coupling system, suitable for steam-era branch terminus layouts and short wheelbase wagons, which uses cheap, unobtrusive permanent magnets between the rails and can be fitted to pretty much any RTR loco, coach or wagon without having to butcher the coupler pockets.  I've noticed that compared to 4mm there are very few branch terminus layouts in 'N' and I would guess that is because, without reliable slow running and a decent coupler system, a branch terminus is never going to be very satisfying to operate.

My design won't suit everyone.  I think sharp curves and especially reverse curves could be a problem: my layout uses Peco medium radius points which are fine, but I haven't yet tested the system on anything tighter.  Like any DIY coupler system, assembly and fitting takes time, and you need fairly steady hands and good eyesight. Having said which, compared to assembling B&B or DG couplers these are a walk in the park.  Replacing steel wagon weights with non-magnetic ones is essential, and older Farish wheelsets with mild steel axles will need changing.

Light, free-rolling vehicles have also given me a few problems with the last vehicle in a train self-uncoupling over the magnets.  Weighting wagons helps a lot: I have also tried slipping a small coil spring over the end of one axle on a Farish horsebox (like the 'truck restraining springs' that Micro-Trains supply to fix the same problem) and that worked well.  The vehicle still rolls freely enough, but the spring gives just enough drag to stop it being pulled forward by the coupler drop arm as it approaches the magnet. 

I tried making a short video of the couplings in operation and found that the only time they don't work reliably (after a fairly long operating session with everything working fine) is when there is a camcorder pointed at them. And then one of the couplings fell off my J39 (defective gluing) and ended the filming session.  I'll try to fix that and have another go.

Next stage is to write up some detailed instructions and get some more frets etched up.  After that I will be looking for couple of volunteers to try them out and see if they can get them to work following the instructions.  If anyone fancies having a go, let me know.

One other thing - I found that Farish wagons with clip on coupler pockets are incredibly easy to convert.  Just unclip the pockets, drill a small hole in the floor and attach the coupler with a small brass screw through the shank. Good news for steam or transition era branch line modellers as the Farish range covers just about every wagon type you might need.

Offline belstone

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Re: Coupling survey
« Reply #125 on: October 01, 2014, 09:48:03 am »
I fitted a new front coupler to the J39 and had another go at filming.  Here it is.

https://www.youtube.com/watch?v=kRXK8v2w0iE

The J39 still isn't running too well, but only one intervention from the 'Hand of God'.  And I need to look at that Conflat, one of the couplers is playing up. But you get the general idea.

It occurred to me that for locos, unless you need double-heading, a plain hook without the lifting bar should work OK and be a lot easier to fit.  There are some locos (older Farish diesels for example) where there isn't enough room for the magnetic drop arm.  So I put a plain hook on the front of the J39 and as you can see it works fine.

Another potential problem is on locos with long end overhangs and no bogie or pony truck - like the J39.  I found that I had to bend the hook outwards slightly to avoid the couplers binding and causing derailments when propelling wagons around curves.  Shouldn't be a problem with  most diesels as the couplers are mounted on the bogies, but I've bought a Farish '08' for trials, as it combines a short fixed wheelbase with long overhangs both ends. If anything is going to give serious problems, that will.

Offline Newportnobby

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Re: Coupling survey
« Reply #126 on: October 01, 2014, 10:03:04 am »
Fascinating bit of shunting there :thumbsup:
Assuming the 'shiny rectangles' to be the Dapol magnets, you seem to have cracked the delayed release of uncoupled trucks (or you have other magnets very well disguised). The static camera does not portray this sufficiently, I fear :hmmm:
On a scale of 1-10 with 1 being the most unhappy, how happy are you with what you have achieved please?
It all looks rather good :claphappy:

Offline belstone

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Re: Coupling survey
« Reply #127 on: October 01, 2014, 10:08:08 am »
I'm still acquiring vehicles from different manufacturers for development purposes.  Today's post brought my first two Dapol products - a new 21 ton hopper, and an older gunpowder van.  Looking good - both have non-magnetic wheelsets (although of two different types) and straightforward spring-loaded T-shank Rapidos in sensibly sized pockets. The van has a steel weight which is easy enough to replace: the hopper has no steel content at all. Happy days.

Offline belstone

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Re: Coupling survey
« Reply #128 on: October 01, 2014, 10:18:15 am »
Fascinating bit of shunting there :thumbsup:
Assuming the 'shiny rectangles' to be the Dapol magnets, you seem to have cracked the delayed release of uncoupled trucks (or you have other magnets very well disguised). The static camera does not portray this sufficiently, I fear :hmmm:
On a scale of 1-10 with 1 being the most unhappy, how happy are you with what you have achieved please?
It all looks rather good :claphappy:

The rectangles are neodymium bar magnets 20 x 5 x 2mm, about flush with the top of the sleepers. Cheap, easy to install and effective. I need to repair the damaged ballast around them and then paint them at which point they should look a lot less obvious.

How happy am I? Ecstatic. Call it 11 on a scale from 1 to 10.  I have a coupler system which is cheap, mostly reliable, not too hard to make and fit and does exactly what I want it to do. And all through fiddling around with brass, plastic and wire in the spare bedroom. It's taken a long time to get there, and there are still some potential issues (mainly around propelling short wheelbase wagons on sharp curves), but hopefully a few people will adopt this system and we will see some more branch terminus and goods yard layouts in N gauge.

Offline belstone

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Re: Coupling survey
« Reply #129 on: October 04, 2014, 01:04:46 pm »
Have Farish given up trying to make standard N gauge couplers work? The '08' I just bought has the worst implementation I have yet seen of a Rapido type coupler in an NEM pocket.  The plastic centring 'springs' in the pocket insert are too weak so the coupler flops from side to side, and there is barely any vertical movement at all.  Easy to convert though - I just popped the insert out of the pocket, built up the plastic shank on the new coupler with thin Plastikard so it was a snug fit in the pocket and secured it with a small screw. Easy and fully reversible if I want to sell the loco later on.

I'm rapidly running out of prototype etched hooks so I'm now working on the definitive 'Mk3' etch design, along with some 3D printed NEM pattern shanks which will save a bit of drilling and filing. Also thinking about a small shunting layout for demonstration purposes. 

Richard

Offline belstone

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Re: Coupling survey
« Reply #130 on: October 06, 2014, 07:47:10 am »


This is starting to look like the optimum shape for the coupler loop - ends bent up and back.  I tried this on four wagons and it works very well, and seems happy on the short radius points in the fiddle yard as well.



The coupler R&D department now has its very own test locomotive.  Ebay bargain, perfect and apparently never been used, for 48.

Offline Bealman

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Re: Coupling survey
« Reply #131 on: October 06, 2014, 08:04:59 am »
Great updates. Thanks for posting!  :thumbsup:
Vision over visibility. Bono, U2.

Offline belstone

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Re: Coupling survey
« Reply #132 on: October 06, 2014, 10:16:29 am »
Looking at that second photo - you'd be hard pressed to say whether that was N or OO I reckon. Sometimes we forget how lucky we are with the quality of the newer Farish stuff.

On the way into work I was thinking about bending up coupler loops which is a bit fiddly.  I now have an idea in my head for a simple jig which will ensure the loops are consistently the same shape. I'll knock up a prototype and then see how much it will cost to get some machined up, or possibly 3D printed in a hard plastic.

Offline Rabs

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Re: Coupling survey
« Reply #133 on: October 06, 2014, 02:04:59 pm »
Hi Belstone,
How easy is it to adjust the separation between wagons with these couplings?  In the second photo above there looks like a big gap between the buffers.  Is it possible to reduce this or people with generous radii on their layouts?

Offline belstone

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Re: Coupling survey
« Reply #134 on: October 06, 2014, 02:32:51 pm »
Hi Belstone,
How easy is it to adjust the separation between wagons with these couplings?  In the second photo above there looks like a big gap between the buffers.  Is it possible to reduce this or people with generous radii on their layouts?

The spacing is about the same as standard N gauge couplers.  Ideally it would be closer, but there isn't a lot of scope to reduce it due to the location of the pivot point, and the need to have enough clearance for the magnetic drop arm.  I might have a look at the CAD drawings and see if I can close up the gap a little bit, but having got the geometry spot on I'm reluctant to start messing around with it too much.

You can get the spacing a good bit closer if you can bin the coupler boxes and attach the shank direct to the wagon chassis, but that solution will not suit everyone.

With N gauge couplers there is always going to be a compromise somewhere - size, reliability, ease of assembly / fitment, compatibility with 'train set' curves and points.  I've gone mainly for reliability and ease of assembly, and just hope people don't find the end result too ugly to live with. I'm curious to see whether it will actually work on No.1 Setrack curves - might have to buy a Setrack starter pack and find out.

 

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