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Author Topic: New coupler development (was Coupling survey)  (Read 29673 times)

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Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #255 on: April 22, 2018, 09:21:22 am »
Looks great. :NGaugersRule:

How is coupling on curves working? Unfortunately not all sidings can be straight...

Have you already an idea on the pricing? I would have to convert about 100 pieces of rolling stock...

When do you think you can release a beta version to be tested by others?

I must convert and fix coupling on my stock somewhen soon...

Coupling on curves is always going to be a problem for any design.  There are several factors: the sharpness of the curve, the distance between outer axle / bogie pivot and coupler face, whether the couplers are fitted and aligned correctly, and finally the massive amount of sideplay in the N gauge wheel/track interface which will cause vehicles to slew sideways on the track. All these factors can combine to prevent the loop from aligning with the hook and dropping over it.  Having said which these couplers will still couple up on a Setrack 2nd radius curve, but reliability on a curve of this radius is not great.

Pricing - I still need to do the costings, but around 1 per pair for the etches and all the other materials. OK, you have to assemble them yourself, but it's still cheap enough.  Bear in mind that you only need to convert vehicles which you intend to shunt with: on fixed rakes of coaches for example, only the outer coupler at each end needs to be changed.

Timetable: I need to sit down and write the instructions which I want to do over the next week.  I have ordered materials to make up 6 - 8 kits for test purposes (8 pairs of couplers to a kit) which will be offered to those people who have expressed an interest in participating in the testing stage.

Richard

Online AlexanderJesse

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Re: New coupler development (was Coupling survey)
« Reply #256 on: April 22, 2018, 09:40:31 am »
Well that sounds pretty reasonable.

With Setrack R2 it is possible to plan also small layouts for switching and with the possible to finetune the distance between cars at this price... and the good looks. I'm all in.

As I am not allowed (SWMBO) to work intensively on my hobby I don't qualify as tester of first quality  :uneasy: and, most probably will have to wait for general availabilty...
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Offline Black Sheep

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Re: New coupler development (was Coupling survey)
« Reply #257 on: April 22, 2018, 09:57:41 pm »

Timetable: I need to sit down and write the instructions which I want to do over the next week.  I have ordered materials to make up 6 - 8 kits for test purposes (8 pairs of couplers to a kit) which will be offered to those people who have expressed an interest in participating in the testing stage.

Richard

If it helps with writing the instructions I'm a graphic designer with some technical drawing ability, although in this day and age it's easy enough to take stage by stage photos and add some text!

Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #258 on: April 25, 2018, 07:59:26 am »

If it helps with writing the instructions I'm a graphic designer with some technical drawing ability, although in this day and age it's easy enough to take stage by stage photos and add some text!

Thanks for the offer, I think I will be OK as I have written an entire book on how to repair old Land Rovers, but might still take you up on your offer if I run into problems with the illustrations.

For now, here's a short photo sequence showing how the couplers are assembled.  This isn't intended as an instruction manual, just a bit of insight into what is needed to make them.



These funny little things are coupler etches as removed from the fret.  Half etched folds on each side to bend up into a U shape, through-etched holes for the loop pivot, and the long thin sticky-out bit is the delay bar.



First stage is to fold the buffer bar up sharply through 90 degrees using smooth jaw pliers.  The hook above the buffer bar is then bent back another 30 degrees.  There are no half-etched lines to help with folding as they would weaken the hook and bar.



The delay bar is now bent upwards 90 degrees and the sides bent along the half-etched lines to form a U-shaped channel.  These are now ready to attach to the shanks.



The coupler etches are now attached to 2mm square styrene strip using cyano adhesive.  The bottom and sides are attached first and squeezed with pliers to ensure they are flat against the shank and all square.  The tab which supports the delay bar is then folded over the top and the delay bar bent to shape with very fine needle nose pliers.



This shows the final shape of the delay bar.  There needs to be enough clearance for the coupler loop to slide freely between the delay bar and the top of the hook.



The pivot hole for the loop can be drilled out using the etched holes provided (note: remaining photos show the previous type of coupler which has some design differences, but the operations are the same).  I find it best to drill the hole half way from each side until they meet in the middle, run the drill bit through and move it back and forth like a file to clear the hole.  This minimises any problems caused by the holes being drilled slightly off-square. Now would be a good time to paint the shank.  I am looking into methods of chemically blackening the etches.  You don't want to paint the coupler once assembled as the pivot will gum up.



Loops are bent up from 0.7mm nickel silver wire using a simple jig - a piece of 1/4 x 1/8 brass tube filed down to a U shape.  They can be trued up once bent - a few small tweaks with the pliers to ensure they are all square and not twisted.



The tail of the loop is passed through the pivot hole ensuring it slides freely...



...and bent down and back to form the drop arm...



...which is then cut short with a pair of wire snips.  Again this is the previous Mk 6 coupler and the different design of the delay bar is obvious here.  The drop arm is left slightly longer until the coupler has been fitted to a vehicle: it is then cut to final length (just above rail height when pointing straight down), and half a dozen turns of fine iron wire wrapped round it to attract the uncoupling magnet, and secured with a spot of cyano.

Now all you have to do is decide how to mount it to your loco, coach or wagon.  That's where the fun really starts - more to follow soon.

Richard

Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #259 on: April 26, 2018, 08:22:05 am »
A few coupler mounting illustrations, and we will start with the simplest version, mounting the coupler direct to the underframe (coaches and wagons).  This requires the existing coupler box to be removed: on many vehicles the box just clips onto the chassis so the vehicle can be returned to standard.



Coupler conversion at its most basic: Farish ex LMS brake van with the coupler box unclipped, and new coupler installed with a small screw through the shank and into the pivot hole for the NEM coupler insert.  Small pieces of Plastikard are used to shim the coupler so it is the correct height.



On Peco wagons the coupler box is moulded to the underframe.  Replacement underframes are cheap, so the easiest way out is to cut away the entire coupler box, fill the space with Plastikard and screw the coupler to that.





One problem is that the long solid shank is quite visually obtrusive especially on vehicles with long end overhangs.  So I came up with this "skinny" version (grey wagon): the shank is cut off just behind the pivot point and the bottom plate folded up and then back in a Z shape, with a small piece of Plastikard glued across the top to strengthen it. I think the extra effort is worthwhile. Farish 16 ton minerals with the original coupler pockets unclipped, the brown one has nuts and bolts holding the couplers on as I drilled the screw holes in the chassis oversize and the screws wouldn't grip on their own. Oops.



For bogie vehicles the coupler can be attached direct to the bogie underframe.  You can see here the advantage of having a straight shank whose length can be varied to suit the application.  This is a Farish Blue Riband Mk1 with the NEM close coupling pocket removed and the bogie rotated through 180 degrees to provide a mounting point - the other end of the bogie frame has a big cutout to clear the original body-mounted coupler box. Again all fully reversible apart from leaving a small screw hole in the bogie frame.



Dapol wagons have an unusual type of spring-loaded Rapido coupler with part of the pocket being attached to the body, part to the chassis.  I took the same approach with this Hop 21 as with the Peco wagons - cut the whole lot out, reinstate the missing underframe with Plastikard and go from there. 



The "skinny" couplers work especially well on this wagon which has unusually long overhangs.  Once painted the result should be pretty unobtrusive. 

Coming soon - NEM coupler pockets about which I have nothing good to say.

Richard





Offline Bealman

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Re: New coupler development (was Coupling survey)
« Reply #260 on: April 26, 2018, 08:31:01 am »
This is wonderful stuff, and a complete credit to you, Richard.  :thumbsup:

I wish you every success.

But isn't it a shame we have to go to such lengths for decent couplings!
Vision over visibility. Bono, U2.

Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #261 on: April 26, 2018, 11:25:07 pm »
I have had a nagging doubt for a while about the height of the coupler above rail level.  I originally set it using a clip-fit NEM shank coupler on a Farish Mk1 as a reference, which gave me a height of around 3.5mm from rail top to the bottom of the coupler loop.  The first few couplers I fitted were all mounted direct to the vehicle underframes: once I started fitting couplers to vehicles with coupler boxes (locos mainly) I found I kept having to fudge the mountings, bend the couplers downwards etc to get the correct height.  I always seemed to be having to adjust down, never up.

Today I acquired three mint boxed Farish cattle vans with NEM couplers. Almost all my existing rolling stock has already been butchered for bulky MicroTrains coupler boxes and I needed some standard unmodified vehicles to work on.  I have spent the evening playing around with different types of mounting, and as a result it looks like I will have to raise the coupler height by 1mm to allow the couplers to fit standard coupler boxes.  That should still give adequate clearance under the bufferbeam for bogie vehicles, and I think it will make it easier to get the drop arm length right which is one of the more fiddly bits of the assembly process.

The bad news is that I now have four locos, 15 wagons and one coach with couplers the wrong height.  The good news is that they were all going to have to be redone anyway: half of them have makeshift modified Mk 6 couplers which need changing for Mk 7s and the rest are all unpainted and will need to come off and have the loops removed so that they can be given a coat of paint without painting them solid.

Hopefully this will be the last design change.  But I said that last time, and the time before that...

Richard

Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #262 on: April 27, 2018, 10:18:39 am »


A bit more fiddling before work this morning.  Excuse the oily thumb, I'm doing engine rebuilds at the moment. This Farish cattle van has a cranked drop arm to clear the front of the coupler box.  Not a new idea but one which featured on my very early designs.  It seemed too fiddly at the time but with the current design of etch, getting the length and angle right is dead easy. So I will build up half a dozen of these to the new standard height and see if the reliability is still OK.



One disadvantage of using the existing coupler boxes is that you cannot mount the coupler very far back otherwise the drop arm will not clear the front of the box, even the new cranked version.  So close coupling is not as good as it would be if you did away with the coupler boxes.  However, this comparison shot shows that even using coupler boxes, the gap between vehicles is closed up quite a bit compared to the standard N gauge couplers.


Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #263 on: May 01, 2018, 08:29:20 am »


Not much time for coupler development work the last few days, but I have been playing with nasty chemicals to try and blacken the metal bits.  This one was done with Birchwood Casey "Aluminium Black" (recommended on one of the finescale forums for nickel silver) with the white plastic shank touched in with a Sharpie marker pen.  I think the result is pretty satisfactory.  Rather than applying the blackener with a cotton swab as per the instructions I poured it into a plastic tub and dunked the entire etched fret into it.  The loops were bent up and dipped prior to fitting.  The chemical leaves a powdery residue which rubs off easily leaving a very pleasing tarnished black-brown finish which does not seem to scratch or chip when handled.

I am steadily working away at the instructions.  These will be quite long - more like a booklet than an instruction sheet - so the plan is to make them available for free download as a PDF, with an option to purchase printed copies. The coupler kits themselves will not come with printed instructions, just a slip with the download address.

Richard


Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #264 on: May 01, 2018, 08:39:15 am »
Beauty and the Beast?


Offline Black Sheep

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Re: New coupler development (was Coupling survey)
« Reply #265 on: May 01, 2018, 08:39:43 am »
Perhaps printed copies come with a 'starter pack' with, say, 6 couplings or just one fret of couplings for people to have a go at building them to see if the coupling suits their requirements / fingers

then 'expansion packs' come with larger quantities of couplings but clearly marked as no instructions (as people will keep the instructions from the starter pack)

Offline Bealman

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Re: New coupler development (was Coupling survey)
« Reply #266 on: May 01, 2018, 08:40:34 am »
Richard, I think you're a genius.  :thumbsup:

Let's hope that N gaugers are watching, and it takes off!

 :thumbsup: :beers:

George
Vision over visibility. Bono, U2.

Offline belstone

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Re: New coupler development (was Coupling survey)
« Reply #267 on: May 01, 2018, 10:10:41 am »
Perhaps printed copies come with a 'starter pack' with, say, 6 couplings or just one fret of couplings for people to have a go at building them to see if the coupling suits their requirements / fingers

then 'expansion packs' come with larger quantities of couplings but clearly marked as no instructions (as people will keep the instructions from the starter pack)

I have thought about a starter pack, with instructions and a couple of magnets to get going with.  One other issue I need to look at, which ties in with the idea of a starter pack, is the assembly jigs.  There are two needed - coupler height, and a loop bending jig. Neither the height nor the loop dimensions are critical in themselves, but if you want your couplers to couple up to ones made by someone else, the height and loop length of your couplers need to be absolutely identical to theirs.  That probably won't happen if people are left to make their own jigs. 

The height gauge is very easy, just a fold-up piece of brass, maybe I could do a "starter etch" with four pairs of couplers and the assembly jigs.  Loop bending jig is more tricky as it needs to be strong enough to bend 0.7mm NS wire around it, so I will have to give that one some thought.

Richard

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Re: New coupler development (was Coupling survey)
« Reply #268 on: May 01, 2018, 10:47:34 am »

If it helps with writing the instructions I'm a graphic designer with some technical drawing ability, although in this day and age it's easy enough to take stage by stage photos and add some text!

Thanks for the offer, I think I will be OK as I have written an entire book on how to repair old Land Rovers, but might still take you up on your offer if I run into problems with the illustrations.



Richard

With a large chapter on preventing rainwater leaks? :D

Offline Black Sheep

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Re: New coupler development (was Coupling survey)
« Reply #269 on: May 01, 2018, 10:40:01 pm »

I have thought about a starter pack, with instructions and a couple of magnets to get going with.  One other issue I need to look at, which ties in with the idea of a starter pack, is the assembly jigs.  There are two needed - coupler height, and a loop bending jig. Neither the height nor the loop dimensions are critical in themselves, but if you want your couplers to couple up to ones made by someone else, the height and loop length of your couplers need to be absolutely identical to theirs.  That probably won't happen if people are left to make their own jigs. 

The height gauge is very easy, just a fold-up piece of brass, maybe I could do a "starter etch" with four pairs of couplers and the assembly jigs.  Loop bending jig is more tricky as it needs to be strong enough to bend 0.7mm NS wire around it, so I will have to give that one some thought.

Richard

The DG couplings loop jig is sold separately and is a block of brass with a hole through it to hold the end of the wire before wrapping around, the instructions do say you can use pliers, not sure if that's with a measurement on to get it correct each time if such a tool exists

 

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