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Author Topic: New coupler development (was Coupling survey)  (Read 27678 times)

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Offline Black Sheep

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Re: Coupling survey
« Reply #195 on: March 05, 2018, 08:31:03 pm »
the coupling on the cattle van looks quite low, or is that just the angle of the photo?

glad to hear progress is progressing, I'm hoping you've got these working well soon so I can get on and build the layout :D

Offline belstone

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Re: Coupling survey
« Reply #196 on: March 05, 2018, 11:39:42 pm »
the coupling on the cattle van looks quite low, or is that just the angle of the photo?

glad to hear progress is progressing, I'm hoping you've got these working well soon so I can get on and build the layout :D

Not quite as low as it looks in the photo but they do sit a good bit lower than the finescale DG / B&B couplers which are designed to mount level with the bottom of the bufferbeam.  The height on my couplers is dictated by the height of the standard NEM coupler box: unlike the DG coupler they can be bogie-mounted which makes a big difference for the radius of curve they will cope with. Here is a side view of the cattle van: the left hand coupler is actually mounted too high and needs fettling.



I have built up another four pairs this evening ready to fit to various vehicles, so I can then start testing in earnest.  The etch design really doesn't need a lot of changes now, so provided I don't have any more snags in testing I should finally be able to get some etches out for people to try. I too have a layout held up waiting for me to get these things working properly. 

Richard


Offline Black Sheep

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Re: Coupling survey
« Reply #197 on: March 06, 2018, 10:10:13 am »

I have built up another four pairs this evening ready to fit to various vehicles, so I can then start testing in earnest.  The etch design really doesn't need a lot of changes now, so provided I don't have any more snags in testing I should finally be able to get some etches out for people to try. I too have a layout held up waiting for me to get these things working properly. 

Richard

Of course it sits lower due to being in the NEM pocket, how daft of me!

I'm a willing volunteer for testing if required


Offline belstone

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Re: Coupling survey
« Reply #198 on: March 09, 2018, 08:19:37 am »
I now have enough vehicles to be able to start testing, so this morning I played with my toy trains over breakfast.



I am getting pretty good reliability on coupling and uncoupling.  Uncoupling is pretty much 100% provided the vehicles are placed correctly over the magnet.  Coupling is around 95%, occasionally two vehicles will not couple up the first time, but will couple on the second attempt.  I have not had any random self-uncoupling since I increased the size of the hooks slightly. That is probably as good as any of the other systems out there. 

I attached the coupler on the Mk1 to the bogie frame which was nice and easy with the fixed shank design: i removed the NEM pocket and associated hardware, and turned the bogie round 180 degrees to give me a flat bit of plastic to put the mounting screw through.  I also had to make a hole in the top of the bogie frame for the guide pin. All easily returned to standard (bar a couple of small holes underneath) if required. 



The delayed uncoupling facility is less reliable.  It works 100% when propelling in a straight line, but tends to recouple on sharpish curves.  Two of my turnouts are small radius and I cannot propel vehicles reliably through those without them sometimes recoupling. Part of the problem is the delay bars themselves, which as mentioned before are an improvised modification and a bit crude.  I could improve reliability by making the loops wider, but that would make the couplers more obtrusive.

I have been toying with the idea of replacing the fixed delay bars with a DG-style lifting latch, but that would make assembly more fiddly and I like having as few moving parts as possible.  I tried making my own lifting latch mechanism but it really needs to be built into the etch, far too fiddly for my clumsy fingers and tired old eyes to make from scratch. So I will play around a bit more, see if I can refine the fixed bars (I had an idea while typing this which might improve things) and then decide whether I really want to go through yet another redesign.

Richard

Offline Black Sheep

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Re: Coupling survey
« Reply #199 on: March 09, 2018, 02:53:49 pm »
I now have enough vehicles to be able to start testing, so this morning I played with my toy trains over breakfast.



I am getting pretty good reliability on coupling and uncoupling.  Uncoupling is pretty much 100% provided the vehicles are placed correctly over the magnet.  Coupling is around 95%, occasionally two vehicles will not couple up the first time, but will couple on the second attempt.  I have not had any random self-uncoupling since I increased the size of the hooks slightly. That is probably as good as any of the other systems out there. 

Many DG users have their vehicles 'handed' with a loop on one end but not the other for the above reason, and I have operated a 2mm finescale layout where I did occasionally have to use the bufferstop at the end of a siding (and a hedge on another siding) to assist with coupling.

Offline belstone

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Re: Coupling survey
« Reply #200 on: March 09, 2018, 11:59:00 pm »

Many DG users have their vehicles 'handed' with a loop on one end but not the other for the above reason, and I have operated a 2mm finescale layout where I did occasionally have to use the bufferstop at the end of a siding (and a hedge on another siding) to assist with coupling.

I am trying to avoid handed vehicles.  On a terminus layout with run round loop you end up needing to have loops on both ends of all your locos, which is the most difficult place to fit them.  (On something like a 2MT 2-6-0 a front coupler with loop would be physically impossible.)  I don't know how bad the loop clash problem is with DG / B&B, but my couplers have much heavier, larger diameter loops which should help a lot. Most of the issues I have had have been more to do with incorrect coupler heights than anything else.

Meanwhile I have been investigating the issue with delayed uncoupling and I am shocked at how bad the geometry is on a small radius Peco turnout.  They are described as 12" radius, but are in effect two straight sections joined by a short, extremely sharp curve, closer to 6" radius than 12".  The result is a really outrageous offset between the vehicle being propelled and the loco propelling it, so the loop slides sideways off the delay bar, then recouples as the vehicles exit the turnout and straighten up.  No amount of fiddling with the coupler design is going to fix this. The photo illustrates the problem nicely: the brake van has already cleared the short curved section and is headed off at a 10 degree angle, while the loco has only just entered the curve and is still pointing straight ahead.



The Peco small radius turnout is not far off an A5 turnout (as supplied by Finetrax) in general dimensions: the difference is that on a proper A5 there is a continuous curve from the frog to the end of the blades, whereas on the Peco version the rails are dead straight from the frog to the blade pivot - see photo below.  I have no idea why Peco designed them this way, a Triang Super Four turnout has better geometry.



The coupler design will handle the transition from straight track to Setrack No. 2 curve with no problems, which is better than I expected and shows just how awful the Peco turnouts are. 

Grrr.

Richard

Offline Black Sheep

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Re: Coupling survey
« Reply #201 on: March 10, 2018, 08:17:20 am »
hahahahaha  :smiley-laughing:

Guess who's marshalling yard has a string of eight small radius turnouts!  :'(

Do you have to do a shuffle over the magnet to uncouple or simply pass over the magnet with the coupling not under tension?

If the latter then a magnet as you exit the point into the siding would resolve things by simply powering the magnet at the right moment.

Offline belstone

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Re: Coupling survey
« Reply #202 on: March 10, 2018, 09:00:42 am »
hahahahaha  :smiley-laughing:

Guess who's marshalling yard has a string of eight small radius turnouts!  :'(

Do you have to do a shuffle over the magnet to uncouple or simply pass over the magnet with the coupling not under tension?

If the latter then a magnet as you exit the point into the siding would resolve things by simply powering the magnet at the right moment.

The couplers need a Kadee-style shuffle over the magnet to set the loop in the delay position, but you are right about the solution - magnets on each exit road rather than at the entry.  For a fan of four sidings like my test plank that means four electromagnets instead of one, which is a pain.  I checked the same two vehicles on a Finetrax B6 turnout where they are fine, and a Peco medium radius (roughly the same size as a B6) which is OK but only just.  The medium Peco is a bit better designed than the shortie, with a gentle curve between the frog and the blade pivot.

N gauge wheel standards don't help. There is so much sideways slop that as the leading wheels run into the turnout, on the small radius one the leading wheelset is already a third of the way along the blades before it starts to change direction.  It then has to change direction by 10 degrees in a length of about 30mm, which makes an effective radius of a little under 8 inches. That's tight.

Richard


Offline belstone

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Re: Coupling survey
« Reply #203 on: March 11, 2018, 11:16:27 pm »
I had a day out at the Huntingdon show and came back with a couple of medium radius turnout to replace the nasty small radius ones.  I also acquired a second hand Setrack turnout.  My test shunting "plank" has now been relayed and incorporates what I call the Impossible Siding, a Setrack reverse curve which should test any coupler system to the limit.

So this evening I had a play and found that the delayed uncoupling system works fine on Setrack (9 inch radius) when it didn't work on small radius Streamline (12 inch in theory).  Here's the proof - dropping off a brake van on the Impossible Siding, hands off.  The glitch at the start was caused by the loco getting tangled up with the (temporary) controller cable. The brake van was uncoupled over the magnet just before I started filming as I don't have enough hands to operate camera, controller and magnet switch at the same time...


Offline belstone

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Re: Coupling survey
« Reply #204 on: March 13, 2018, 08:22:38 am »
Yesterday my 6-core cable finally arrived, meaning I could tidy up the controller and wiring so it is no longer draped across the track.  I changed the microswitch on the back of the controller for a smaller one - still looks a bit of a lash-up, but works beautifully. 





So I made another short video, just a loco and a few wagons running backwards and forwards across the magnet, showing how the delay feature works.  A couple of small glitches: the coupler on the back of the cattle wagon needs fettling as the loop is slightly below the horizontal at rest, hence needing a good thump to recouple.  And a demonstration of what happens if you uncouple a single free-running wagon and then propel it off the magnet before letting go of the switch. 

I made a longer video - 8 and a bit minutes of hands-off shunting in and out of all 5 sidings - but the quality wasn't great so I haven't uploaded it. Bearing in mind that the couplers are an improvised lashup with bits glued and soldered to them, things aren't going too badly at the moment. I'll get the revised etch drawings done and sent off to PPD this week, hopefully.  I need to look into chemical blackening of nickel silver as well.

Richard


Online Newportnobby

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Re: Coupling survey
« Reply #205 on: March 13, 2018, 10:13:36 am »
That is very impressive, Richard

Offline Black Sheep

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Re: Coupling survey
« Reply #206 on: March 13, 2018, 11:46:24 am »
Chemical blackening I'd leave down to the person building, but would be interested to hear what you use as this is a route I was going to go down when planning to use DG couplings.

Does the coupling have a name yet?

DG
B&B
AJ
Belstone

?

Offline belstone

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Re: Coupling survey
« Reply #207 on: March 13, 2018, 12:07:04 pm »
Chemical blackening I'd leave down to the person building, but would be interested to hear what you use as this is a route I was going to go down when planning to use DG couplings.

Does the coupling have a name yet?

DG
B&B
AJ
Belstone

?

The B&B couplers come ready-blackened, I think those are etched in stainless steel. I like the idea as it avoids the risk of clogging up the whole thing with paint.

I am calling this the Magpie coupler - Mag for Magnetic, and Magpie because it shamelessly steals design features from pretty much every tension-lock coupler since the days of O gauge Hornby tinplate :)

Richard

Online Newportnobby

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Re: Coupling survey
« Reply #208 on: March 13, 2018, 01:02:04 pm »
That's just brought back memories of Jenny Hanley  :heart2: presenting Magpie, c/w theme played by the Spencer Davis Group!
 :oopssign: :sorrysign:

Offline tutenkhamunsleeping

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Re: Coupling survey
« Reply #209 on: March 13, 2018, 01:26:50 pm »
c/w theme played by the Spencer Davis Group!

 :offtopicsign:
Blimey, never knew SDG did that! Caught Steve Winwood live about 4 years ago - excellent!

 :offtopicsign:

 

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