BLI P70 - Correcting Coupling Distance How-To

[Maletrain]

The prototype drawings I have show about 26" between passenger cars, which is filled by diaphragms.  So, to improve the appearance of model passenger cars, we need to make them look similar to the prototype, but we still need to be able to make them run reliably on the trackage as we model it.  So, there are going to have to be trade-offs.  That should be obvious to all who are reading this.

So, the real question is how small should the radius be that we design our coupling distance and diaphragms to accommodate.  Can we discuss that here?

I think it is unreasonable to make all after-market parts be designed such that all lengths of passenger cars can operate on 9" curves.  What do others think?  And, let's be specific about what lengths of cars we are talking about for our radius choices.

My personal choice is to keep 80'-85' passenger cars on radii of 19" or larger, but I will subject 60' shorties to 13.5" radii on my branch line.  That should allow me to keep things moving reliably and aesthetically in the space I have.  But, others won't necessarily have the space to do that. I will be satisfied with diaphragms fill the gaps between cars at coupling distances that are somewhat larger than N scale 26" (which is only 5/32").  I am trying to get my freight cars down to 3/16" spacing (30 scale inch separation).  But, the diaphragms in passenger cars can make larger separations still look pretty good.

So, what distances do others want?

[robert3985]

I like the looks of ALM diaphragms on the ends of every passenger car...looks a lot like the prototype...so, I won't be interested in the whole idea of a separate "diaphragm" to be applied between cars after they're coupled up. 

I don't find that assembling and painting the ALM diaphragm kits are difficult in the least...very easy IMO...and they work perfectly, and look good too. 

I assume that developing an entirely new product that looks okay and functions reliably is going to take exponentially more time than assembling, painting and installing ALM diaphragms on an entire fleet of passenger cars. 

And, I agree 100% with @bbussey Brian about them.  Taking the time and effort to develop an inferior product, no matter how good it might look or how perfectly it might function. It isn't attached to the car and doesn't add to the car models...just to coupled up trains, and adds much more time wasted inserting them between cars every time a passenger train is put on the track...and need to be kept track of when the trains are removed from the layout...as opposed to the ALM diaphragms, which just function once coupled without any extra effort or thought, and look good when the passenger car isn't coupled to anything.

What is wrong with only running passenger trains on straight or broadly curved track?  I must be missing something here.....   

If you actually read my post, you'll not find any intimation that there's anything "wrong" with running passenger trains on straight or broadly curved track.  However, it's pretty obvious that most layouts have track plans which incorporate trackage that will cause passenger cars equipped with the proposed insertable diaphragms to derail, or the product will fall out...on such common trackage items as S curves, small turnouts, tight radii in yards or other places that require them for the track plan to fit.

I wouldn't want to feel the need to limit my passenger operations, or where the trains go just because of some inferior product inserted between cars when ALM diaphragms already look and work just fine with no extra effort after they're installed, even on less than ideal track work.

But, if you guys what to spend the time, thought, money and effort to develop insertable N-scale diaphragms between coupled cars, then go for it.  However, I would be remiss to not express my opinion that it'll be a wasted effort since a much superior product is already out there and has been for a long time.

Cheerio!
Bob Gilmore

[NorsemanJack]

But, if you guys what to spend the time, thought, money and effort to develop insertable N-scale diaphragms between coupled cars, then go for it.  However, I would be remiss to not express my opinion that it'll be a wasted effort since a much superior product is already out there and has been for a long time.

Cheerio!
Bob Gilmore

Not sure who "you guys" is.  A fellow poster posted what I thought was a clever suggestion.  He was subsequently told by several posters that basically he has a stupid idea and would be wasting his time.  This generally isn't how we "encourage" fellow modelers.  I was merely sharing a positive opinion that the idea might have merit.  That said, I'm not in a position to pursue such things at this time.  I've never really liked the look of those other diaphragms which you seem to feel are the final answer for everything.  Too each his own.

[thomasjmdavis]

The prototype drawings I have show about 26" between passenger cars, which is filled by diaphragms.  So, to improve the appearance of model passenger cars, we need to make them look similar to the prototype, but we still need to be able to make them run reliably on the trackage as we model it.  So, there are going to have to be trade-offs.  That should be obvious to all who are reading this.

So, the real question is how small should the radius be that we design our coupling distance and diaphragms to accommodate.  Can we discuss that here?

I think it is unreasonable to make all after-market parts be designed such that all lengths of passenger cars can operate on 9" curves.  What do others think?  And, let's be specific about what lengths of cars we are talking about for our radius choices.

My personal choice is to keep 80'-85' passenger cars on radii of 19" or larger, but I will subject 60' shorties to 13.5" radii on my branch line.  That should allow me to keep things moving reliably and aesthetically in the space I have.  But, others won't necessarily have the space to do that. I will be satisfied with diaphragms fill the gaps between cars at coupling distances that are somewhat larger than N scale 26" (which is only 5/32").  I am trying to get my freight cars down to 3/16" spacing (30 scale inch separation).  But, the diaphragms in passenger cars can make larger separations still look pretty good.

So, what distances do others want?

Checking some from my own "fleet"- measuring distance between bodies of pairs of Rapido and Walthers and Kato cars, which I think are the closest coupling "out of the box" of cars I have, I measure .275" as they sit there, and get about .285 if I "stretch" them out- say what one might encounter in a 12 car train v 2 cars sitting in a station.  While that is a measurement over 48 scale inches, they do look pretty good.  Checking 2 random Kato 85' cars, I got a measurement of .24 sitting in place, and .259 stretched (more spring in the coupler?)- so on the order of 40"-43"

I suspect that if we reduce down to actual prototype spacing, we will need to increase our curves out to prototype radii.  Which as I said in an earlier post, would be about 48".

NMRA minimum for 85' cars with diaphragms is 21"- so that would be to me the logical "minimum radius" to shoot for.

For my own purposes, I might build a few of my car sides into "show cars" at some point- ie strive for as much prototype accuracy as I can manage, where a really accurate diaphragm would be a big help- but since the cars would for contest or photo purposes, would need to be individual.

I will be trying to achieve some uniformity in my fleet, so will be modifying cars with especially obnoxious spacing.  But I doubt I will ever get to the point of doing so with Kato or Rapido cars- more likely to settle for a "Kato" spacing of .25" or thereabouts, and leave the Rapido, Walthers, etc cars alone. 

Which is a long way of saying- if it is a pair of diaphragms with 26" {prototype) spacing, and come apart, I might be in for a few pair.

If you want something specific for yourself, go ahead and make it.  If I see it and want some, I will let you know.

If it is a "tube" between cars that looks more realistic than an ALM, I might buy a several dozen pairs for use on cars that will not uncouple in an operating session.

If it is a pair of diaphragms with a common model spacing - where the pair would fit the .28 ish space between the Rapidos with enough flex to also work in the slightly tighter Kato spacing, AND looks more realistic than an ALM, I might adopt it as the "company standard" if it becomes available in quantities.

But that is just me. 

PS: my objection was not to the idea, but to the implication that ALM parts were difficult to work with.  If you can build a better mousetrap, go for it.

PPS: On being told something is impossible, what one of my professors said to me 45 years ago, and proved true in many years designing and building sets and rigging lights- "The difference between the difficult and the impossible is that doing the impossible is usually more fun." (Prof. Russell Whaley)

[chicken45]

I hate everyone and everything!

[mmagliaro]

My 80 footers have 30" (scale) space between them, as measured at the ends of the car sides.  They have part of the ALM diaphragms on each end, so they don't "accordion" out... they are just glued to the existing vestibule parts that were already molded on the cars, but having that part of the ALM unit on there closes up the gap somewhat. On 24" curves, they do not touch.  On 18" they occasionally graze each other, but they don't derail.  In reverse, pushing a 6-car train, it's dodgey.  As long as I take it slow, they work.  But if I push through an 18" curve with any speed, sometimes one car will force another once off the track.  So I just don't do that.

If you are soliciting opinions on what capabilities a product should have, I'd say
80 footers
18" radius curves
30" scale spacing

should be what we're shooting for. 

[Point353]

I hate everyone and everything!

You can audition to be the Honorary Curmudgeon's understudy.

[CRL]

I hate everyone and everything!

Nobody can accuse you of not being inclusive.

[Angus Shops]

I find the ALM diaphragms over scale and 'clunky'; while they fill in the gaps between cars, they don't really look much like prototype diaphragms, especially when viewed on the end of an uncoupled car. But that's me, and for my purposes, I find I don't really need them.

My layout (Canadian Pacific in the Rockies in 1958 with a full complement of the passenger trains of the time) uses 24" radius curves and any switch likely to see a passenger train on the diverging route is a #9. There is no passenger switching, trains proceed in one direction with no backup moves. This allows me to use rigid scale diaphragms castings with the coupling distance spaced so there is only a small gap between the diaphragms when the train is being pulled. When the train is stationary or being pushed the diaphragms are in contact with each other which allows for close to scale car spacing for photos and etc.

My layout is a point to point style with stubb end staging at both ends with no provision for turning trains. The passenger trains are restaged by coupling another set of locos to the rear end of the train, cutting of the the head end locos and pulling the train 'backwards' around the layout. It's a bit of an onerous process but I still enjoy 'running trains' even if they're just restaging runs. The layout was designed to have a siding to perform a run around move on close to the throat of the staging yard to minimize the length of the final back up move into staging. The staging yards have #7 switches, but I use the tracks with the least diverging routes for passenger train staging. A 'staight shot' backup move is usually not a problem even when a 12 car train is being pushed with all the cars pushing on their diaphragms. I go slow and if something looks amiss I stop the backup and pull forward enough to stretch out the train and relieve the pressures on the diaphragms. Usually works; not always.

This works for me. I can easily see why this would not be appropriate for any layout with tighter curves, smaller switches, passenger car switching, or regular back-up moves (in others words, possibly ever other model railroad other than mine). I've ordered two sets of Rapido's Canadian; I'll be interested to see how they manage the coupling distance/diaphragm conundrum, and if I'll feel the need to modify these cars...
Geoff

[CRL]

If closing the visual gap between the cars is the goal, maybe an oval of very soft black foam rubber could ride in the center of the diaphragms between the cars to prevent light from showing through as the cars go by. If not, then forget I said it. 

[eja]

I have several cars with a single AMB diaphragm installed on one end.  Prototype? No !  Mostly fills the open space ?  Yes.  Looks good ?  Yes (to me)    Fills the space - usually.  Avoids many of the issues associated with curves and tight radii?  Yep.

YMMV ......
ed

[peteski]

I find the ALM diaphragms over scale and 'clunky'; while they fill in the gaps between cars, they don't really look much like prototype diaphragms, especially when viewed on the end of an uncoupled car. But that's me, and for my purposes, I find I don't really need them.
. . .
Geoff

I have to agree with Geoff.  Yes, those functioning diaphragms fill the space between the cars but yes, they are overscale and clunky, and they donn't look very prototypical.  That is why I was really surprised that Bob Gilmore, whom I consider a perfectionist, uses and endorses them.  Looking at his meticulously detailed models (the weathered Big Boys, UP cabooses, very realistic trackwork, and pretty much everything he does, I just don't see him accepting the look of those ALM diapgrams on the ends of his passenger cars.  Call me puzzled. 

[wazzou]

Call me puzzled. 

From here on out, you'll be known as puzzled.

[robert3985]

I have to agree with Geoff.  Yes, those functioning diaphragms fill the space between the cars but yes, they are overscale and clunky, and they donn't look very prototypical.  That is why I was really surprised that Bob Gilmore, whom I consider a perfectionist, uses and endorses them.  Looking at his meticulously detailed models (the weathered Big Boys, UP cabooses, very realistic trackwork, and pretty much everything he does, I just don't see him accepting the look of those ALM diapgrams on the ends of his passenger cars.  Call me puzzled. 

Dear Puzzled, ALM diaphragms have their imperfections for sure, but so does oversized rail, oversized spikeheads, fugly and out-of-scale telegraph pole crossarms, overly wide wheels, overly tall flanges, NMRA specs on turnouts, directional headlights, classification lamps that can't be turned on or off or change from white to green, no track furniture on hand-laid N-scale track & turnouts, every turnout throwbar ever made, non-rotating over-scale switch stands, attachment screws in smoke stacks, too much distance between engines & tenders & cars, slinky effect using Micro Trains couplers, oversized Micro Trains couplers, oversized every other brand couplers other than MT True-Scale couplers, mold parting lines on the noses of Kato F-units, grossly oversized engineering plastic handrails & stanchions, molded on grab irons, molded on lift rings, weird headlight color temperatures...ad infinitum.

Although I have attempted to construct and make models as "perfect" as my skills, tools and knowledge would allow me since starting building models at the age of seven, I have never deceived myself into thinking that I had constructed or assembled any model that was actually "perfect".  In my N-scale modeling experience, I have attempted to improve aspects of the hobby by accepting new, higher standards such as the early adoption of low-profile flanges on all of my Ntrak trains (which I turned on my lathe) and converting as soon as I could in the early 80's to Kadee N-scale couplers...then to MTL Z-scale couplers on my N-scale trains.  I never used C80 flex or turnouts on any of my Ntrak modules, but first, used Rail-Craft C70 flex with hand-laid C70 turnouts...then using Rail-Craft C55 mainline track, with hand-laid C40 sidings, spurs and branchlines...all with hand-laid turnouts...but still ground my teeth at the tallness of C55 and the railhead width of C40.

Many of the above items I have learned to live with in my 4 decades of modeling in N-scale, and some items are much better than they used to be, but still not "perfect"...including ALM diaphragms, which (although not perfect) are the best product out there to represent diaphragms between diesel engines and passenger cars in N-scale.

The problem with the the insertable "diaphragms" as a viable product IMO is the whole concept of them.  (1) They're not attached to the train...they just stay in place due to friction which means (2) Every time you put a passenger train on the layout, you have to insert them, or take them out when taking the train off the layout which (3) Requires storage for the myriad press-in diaphragms and (4) Much extra time to insert, remove and store.  Also (5) They're not attached to the ends of each passenger car which detracts from the appearance of each passenger car model.  Additionally I believe (6) they'll fall out eventually somewhere on the layout and (7) cause derailments on track that is less than ideal for running long passenger cars. Finally, the insertable "diaphragms" will require ( 8 ) coupler modification and (9) standardization of distance between coupled up cars and (10) modification and removal of obstructions and molded-on vestibule opening details on some passenger car models and (11) painting will diminish their functionality if a more prototype appearance is wanted.

The main advantages they may have over ALM diaphragm kits is (1) they won't require assembly before they can be used for a lot of cars and (2) they could be made to look less "clunky" if extra effort and research is done to get them to look more prototypical, although prototype diaphragms have separate parts on the sides and tops, which if included in the insertable "diaphragms" will negate their simplicity while increasing their fragility.

To be fair, a comparison of the pluses and minuses of the ALM diaphragms should be made:

(1) ALM diaphragms don't look strictly prototypical (no folded bellows, molded on top springs) (2) Require modification of vestibule ends on many RTR passenger cars (3) Require standardization of distance between cars on many passenger car models which also requires (4) modification of coupler mounting or type and (5) often require painting to look prototypical and (6) require assembly.

The advantages of ALM diaphragms are that (1) They are readily available NOW (2) They come in various configurations to fit most engines and RTR passenger cars (3) They can be easily painted without any loss of functionality if you want to (4) They're attached to the ends of passenger cars so (5) they don't need to be stored or (6) inserted or (7) removed when making up a train or taking a train off the layout. ( 8 ) They also don't fall off because of non-ideal track conditions and (9) Trains can be made up just by coupling up the cars with ZERO added effort or thought once they're properly attached to the vestibule ends. Finally, the ALM product (10) Improves the appearance of single engines and cars, even if clunky since most passenger cars had diaphragm on their ends and an N-scale car without something hanging out there is clearly missing something.

So, both styles have their advantages and disadvantages, but the ALM product's design from an appearance and functionality aspect is clearly superior to any simple, one-piece insertable product.

However, I would be very supportive of a new N-scale diaphragm product which had all of the ALM product's advantages but looked more prototypical and had finer details, but...as opposed to my opinion about hand-laying both C55 and C40 track, I'm not concerned enough about the clunkiness of the ALM product to ever consider scratch building better-looking diaphragms.

Before I would do that, all of my passenger cars will have to have separate grabs, vestibule stairways, body-mounted True-Scale couplers in new coupler pockets, steam and brake lines, correct interiors including window blinds/shades, correct colors and passengers.  They will also have to be the correct cars with correct names, numbers, roof vents, roads and colors...then, I'll start worrying about my clunky ALM diaphragms.

In the meantime, if the insertable diaphragms ever comes to the market, I won't purchase them...simply because of the bother of using them, even if they remain in place while the train is running, and don't derail cars.

Cheerio!
Bob Gilmore

[Angus Shops]

I'm a little surprised that MT or Rapido, with there demonstrated wizardry in casting tiny plastic parts to make up otherwise really great scale models of various passenger cars, haven't created a more refined, closer to scale, functional diaphragm. MT's heavyweights have diaphragms that are 'functional' in that they move when pressed, but they are too small to close the gap between cars, and they're too stiff to function properly even if they were in contact with each other.
Geoff