BLI P70 - Correcting Coupling Distance How-To

[bbussey]

Well, I am going to have to disagree with that.  Assembly of those diaphragms is tedious, at best.  And, they need to be glued to the cars after whatever rigid representations of diaphragms have been removed.  Plus, they look a bit over-sized to me on their striker plates.  What I am suggesting would at least by pass the assembly and gluing, even if the rigid diaphragm removal is still needed. (Some models just have snap-out parts for diaphragms.)

No more tedious than anything else. Certainly not more tedious than shortening the coupler distance on the BLI P70. And the striker plates on the streamlined version can be reshaped to match other prototypes, including the P70 profile.  The heavyweights version already has a smaller profile.  And since when is gluing parts together a deterrent?

Some models such as Rapido’s New Haven prototypes have semi flexible diaphragms that don’t mate but come close enough that I can live with the .030” or so gap. Other models however need something. The ALM designs (and the clones on the InterMountain/Centrailia models) are the most practical for simulating an enclosed passage between operating passenger equipment.

[thomasjmdavis]

My recollection from asking the question 20 odd years ago is that the ALM/Centralia/Des Plaines striker plates are the size they are to accommodate the radically undersized curve radii of model railroading (compared to the prototype).  NMRA minimum mainline radius for 85' passenger cars with diaphragms is 21.5
https://nmra.org/rp-11-curvature-rolling-stock

and I bet that there were (and still are) many customers who expect the diaphragms to work on radii below 21.5".

As Bryan pointed out, the strikers can be easily modified.  And I find the whole process much less nerve wracking than wire hand grabs or carving up underframes to put the battery boxes where they belong.

Except, of course, those cars with cast on "representations"- I can't seem to get these off without at least scratching the paint, and often gouging the end, no matter how careful I am.

[bbussey]

... Except, of course, those cars with cast on "representations"- I can't seem to get these off without at least scratching the paint, and often gouging the end, no matter how careful I am.

I use flat-face fingernail (or toenail) clippers to remove the builk of the cast-on diaphragm frames, followed by a #16 A-Acto narrow blade for the final clean-up.  That's been the best method I've found at preserving the surrounding details and paint.

[thomasjmdavis]

I use flat-face fingernail (or toenail) clippers to remove the builk of the cast-on diaphragm frames, followed by a #16 A-Acto narrow blade for the final clean-up.  That's been the best method I've found at preserving the surrounding details and paint.

Thanks Bryan,
After reading your post, I picked up a straight clipper (no, one does not go into one's wife's nail care kit for modeling tools) while running some errands and just tried that out.  Works great.  Just took the cast in diaphragm off an old Con Cor baggage that is the subject of a kitbash.  I think if I can find a smaller "fingernail" version, it might even work better.  But even with the "toenail" size, it is probably at least 1/2 the time, and much cleaner, than trying to hack the thing off with chisel blades and/or razor saw.

[NorsemanJack]

I do understand the sliding aspect of the separate diaphragms on the coupled cars.  That is most important on S curves, such as encountered in yard ladders and crossovers.  I have actually stood in prototype cars being switched and watched what the diaphragms do on S curves.  Given our tighter model curves, I think that is the biggest challenge for what I suggested.

But, some folks seem to have already made accordion-fold paper inserts and stuck them between coupled cars.  I am just suggesting that something similar but more realistic could be made and would probably be at least as popular as many of the other "detail parts" now for sale, perhaps including the American Limited versions. 

As for tedious installation - I think that what I am suggesting would be a lot easier to install than a pair of American Limited diaphragms.  You could probably insert a portion that fits inside the door on one car, then push the cars together so that they couple and at the same time, an identical portion fits into the door of the other car.  Of course, you might have to cut off any cast-on rigid representations of diaphragms from some manufacturers' cars for either case.

@Maletrain  I agree with everything you've said.  Ignore the crosstalk.  Your description above makes perfect sense.  As an example, let's consider Kato's wide variety of passenger sets.  The "diaphragms" from the factory are all almost identical.  The factory car spacing is also fairly consistent, with some exceptions.  A drop in "filler" diaphragm that is held in place by the two existing pieces would seem fairly straightforward.  Even a simple piece of foam glued between two rigid pieces that fit the factory diaphragm openings would be a vast visual improvement over the current "jump the gap" look.

[robert3985]

@Maletrain  I agree with everything you've said.  Ignore the crosstalk.  Your description above makes perfect sense.  As an example, let's consider Kato's wide variety of passenger sets.  The "diaphragms" from the factory are all almost identical.  The factory car spacing is also fairly consistent, with some exceptions.  A drop in "filler" diaphragm that is held in place by the two existing pieces would seem fairly straightforward.  Even a simple piece of foam glued between two rigid pieces that fit the factory diaphragm openings would be a vast visual improvement over the current "jump the gap" look.

And, it would derail the cars on anything other than straight or broadly curved track.

Hey, give it a try.  Maybe it'll work like a dream...but, I seriously doubt it.

I'm totally happy with American Limited diaphragms...I mean, like, totally man! 

Cheerio!
Bob Gilmore

[Maletrain]

The design that is slowly building in my head involves removing the cast-in or snap-on diaphragms to get the full  inter-car distance available for the dual-diaphragm insert to have the space needed to accommodate the variety of relative motions between the car ends.

I am currently thinking about a pair of "M" shaped springy wires, mounted vertically, one on each side of the passageway.  The sloping parts of the Ms would look like the rods that are visible outside the prototype diaphragms.  At the intersections of the bottoms of those Ms, a plate representing the pair of prototype striker plates would be fastened.  Some sort of thin fabric would be made in an inverted U shape to represent the passage cover, and would be fastened to the striker plate(s) in the middle and to frames with doorway-fitting plugs on each end.

The trick is to make the vertical legs of the Ms swivel where they pass along the car sides.  If I can make that happen with a simple, but reasonably robust design, then I think these gizmos would be pretty good at accommodating the relative end motions of the cars.  Imagine the cars in a curve, which would cause one of the Ms to open the V shaped angle at the bottom, while the other closes that angle a little.  Now imagine the cars on an S curve, which would cause the Ms to swivel so that looking down on them makes their arrangement go from being rectangular to being a parallelogram.  If one needs to open the angle of the M and the other needs to contract the angle of the M a bit for portions of the S curve, they can do that at the same time.  Because there is no floor or rigid ceiling to the passageway, this should not tend to derail cars so long as the vertical shafts of the M springs can swivel freely enough.

Making such a gizmo with modelers' tools in a home shop seems like a serious challenge, and I have too many other things on my plate to give that a try right now.  But, a manufacturer should be able to execute such a design without too much sweat. 

As I said before, if they were readily available, it would be a pretty simple task to insert and remove them in rolling stock.  The problem is that they are not readily available, and I probably need to fabricate at least one to make sure that it works as I think it will, plus can be made to look decent, which is the real goal of the effort in the first place.

[bbussey]

Or, you could simply install ALM diaphragms.

[Mark5]

Or, you could simply install ALM diaphragms.

Bryan,

I guess you mean the 8400. Does the 8400 work well with MTL, Lima and other heavyweights? (aside from the "official" Rivarossi spec).

http://www.americanlimitedmodels.com/n-diaphragms-for-heavyweight-cars-2-car-set-black

Mark

[bbussey]

Bryan,

I guess you mean the 8400. Does the 8400 work well with MTL, Lima and other heavyweights? (aside from the "official" Rivarossi spec).

http://www.americanlimitedmodels.com/n-diaphragms-for-heavyweight-cars-2-car-set-black

Mark,

That’s the black heavyweight style, correct?  Yes, that’s what I’m going to use when I follow Chris’ body-mounted coupler modification this weekend. Also, I’m probably going to use a Liquitex permanent paint marker on the frame, burnt umber I think is the closest shade to Pennsy Tuscan red. I use them now on MTL flexible Celcon plastic parts, and it never flakes or chips.

[bbussey]

And yes, I use them on MTL heavyweights also. You discard the existing diaphragm and fill the channel with .030 x .030 styrene strip to provide the foundation for the ALM frame.

[Maletrain]

Or, you could simply install ALM diaphragms.

Seems strange that Bryan feels compelled to keep pushing ALM diaphragms.  I have installed some.  They are not a mystery to me.  But, they are more difficult to assemble and install than something that I am thinking would better suit my intended use, if it were available.  Somehow, Bryan doesn't seem to agree that anything better/different should be contemplated.  I guess he thinks that ALM diaphragms are perfect.  Maybe they are for him.  But, Rule #1 for Model Railroading says that I get to do things the way I want to do them on my layout.  I think that also applies to asking for products that help me to do things the way I want to do them.  And, constructively discussing ideas here helps improve the ideas and perhaps turn them into useful additions that others might also find useful.  So, let's not end a discussion because Bryan is not on-board with an idea.

[NorsemanJack]

And, it would derail the cars on anything other than straight or broadly curved track.

Hey, give it a try.  Maybe it'll work like a dream...but, I seriously doubt it.

I'm totally happy with American Limited diaphragms...I mean, like, totally man! 

Cheerio!
Bob Gilmore

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

[thomasjmdavis]

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

In my case, planning to model Dearborn in Chicago- will need to run backwards through double-slip switches and tight S curves (just like the prototype) and a 12 car train changing directions 5 times over its own length.  Peco now holds my mortgage.   

[Lemosteam]

The convo is getting so off topic, that we have forgotten why the thread is here. To criticize the fact that BLI's coupler choice left much to be desired in the coupling distance department!. to discuss improved lighting, and to offer up reasonable solutions to solve thes issues.

The diaphragm question is a reasonable one, and I want to see if I can develop a coupling distance that will work without too much tear up.

I have a section of radius on my small layout that is very tight and as I receive prints, I will test my concepts there, with the as cast diaphragms, as the cars are on loan to me for measurement only.

This will help me understand what distance is appropriate for aftermarket diaphragms.