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 26' Flatcar in Fn3
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Engine Wiper

Posted - 08/15/2020 :  01:26:59 AM  Show Profile  Visit BreizhSteamer's Homepage  Reply with Quote
After preparing the frame and floor boards, construction can continue with the underframe. The main components are the body bolsters, needle beams and trusses. Unfortunately, I don't have got a complete set of diagrams, so I had to guesstimate concerning the longitudinal and cross trusses. However, it's not rocket science.

Since I've already cut all the floor boards to length, an assembly rehearsal was in order. Again, everything was loosely put together, nothing can be glued, yet.

The frame is layed completely with boards for test purposes.

And while one's at it, there can (Nah: must!) be a short ride of the whole contraption on top of one of the demonstration waggons. There was some concern because the flatcar is going to be quite a bit wider than the locomotive. However, while building my first scratch-built flatcar, I don't want to bow to a loco which isn't to scale. So I fall back to my company having purchased a small loco and some standard cars.

The assembly is test run on a test waggon.

But let's get on with it: The body bolsters and needle beams are cut to length, notched and assembled for test purposes. The needle beams will later carry the queen's posts, which enhance the distance between the frame and the trusses and hence facilitate the leverage.

The body bolsters and needle beams are fitted into the frame.

Now the really fiddly part commences. The cross trusses have to be threaded into the frame. They pass the forces that exert onto the side sills on to the king pin in the middle of the car. Because the operation session is drawing closer and I want to see some results, this time I've bought square nuts and washers in M1.6. The truss plates are cut from 0.3 mm brass sheet.

The trusses supporting the body bolsters are mounted.

A close-up of the nut and washer fastenings. The boxes of my Accucraft's knuckle couplers are in place, too. Later on, I will have to add the draft timbers which pass the pull and push forces into the frame. By the way, the flawed spots on the side sills are quite a welcomed side effect, they can stand in as tear and wear.

The knuckle couplers are directly screwed to the dead blocks.

Now that both sides are prepared, the fame is finally white-glued. The picture shows how the body bolsters are being pressed to set the glue, after the sills have already been fixated.

The body bolsters are being white-glued to the frame.

If you thought the cross trusses had been tricky, you will love the nex part. The longitudinal trusses are layed out along the whole length of the waggon and fixated at the end sills with square nuts and washers. I also had to add some support on top of the body bolsters, the diagrams hint at some metal plates. I couldn't spare the time and nerve for those. That might be something that I'm going to change for the other flatcars.

The trusses are threaded into the frame and additionaly secure the knuckle couplers.

And that's the completely trussed frame from below. Of course the queen's posts are missing, there are some difficulties in delivery right now. So I've left some length of rod at the end sills in order to keep it in reserve for the queen's posts' assembly.

The trusses are complete.

The floor is boarded in the usual fashion: A bit of white glue to lend the model some more endurance and the planks are nailed to the side sills. That's child's play with red cedar: One simply picks a nail with a pair of pliers right below its head and skewers it into the wood all the way to the stop. Then a quick shove with the now closed pliers from above: done and no bent nails!

The floor boards are white-glued and nailed to the frame.

The last board often needs to be trimmed in width, as this one. I always rejoice on how the grooved boards form up a closed and very sturdy floor. By the way, one can easily spot several imperfections in the individual boards which I allowed quite deliberately to happen. They give the floor an irregular and gappy appearance and also contribute to the waggon's character.

The last floor board is trimmed to size and fixated.

Country: France | Posts: 104 Go to Top of Page


Premium Member

Posted - 08/15/2020 :  09:08:13 AM  Show Profile  Reply with Quote
A fine job so far!!


"And in the end, it’s not the years in your life that count. It's the life in your years." A. Lincoln

Country: USA | Posts: 13047 Go to Top of Page


Premium Member

Posted - 08/15/2020 :  11:51:24 AM  Show Profile  Send Guff an AOL message  Reply with Quote
Very nice!

David Guffey

Country: USA | Posts: 2037 Go to Top of Page

Engine Wiper

Posted - 12/16/2020 :  03:43:33 AM  Show Profile  Visit BreizhSteamer's Homepage  Reply with Quote
Hello everyone,

sorry for the long hiatus, there's been a lot of stuff going on lately, most of it unrelated to model railroading I'm afraid.

Jerry, David, thanks for the kind words!

I'm continuing my report with some pictures of the operation session. It was that date coming up which spurred me into building this flatcar. Since we only had a relatively short time for operations and I was preoccupied with test runs, there are only a few pictures. In return, I learned lots of lessons.

Lesson #1: The test track is not the reality
While test-running my test waggons I actually managed to navigate body-mounted couplers through a R1 curve (600 mm radius). Apparently, I was quite lucky because on my friend's layout I've experienced several derailments, even in R3 curves (1200 mm radius). With couplers mounted to the waggons' frames, the tracks' foundations obviously play a major role.

On this occasion it becomes clear, that the flatcar is really sturdy. In the following picture one can clearly see how the test waggon bends under its load, since it's made from a single 6 mm thick board of plywood. The flatcar on the other hand uncomplainingly carried loads in excess of 10 kg.

The first short train, consisting of bulkhead, test waggon and the new flatcar.

Lesson #2: The bogies need some play
My friend's layout dates back to the 1990s. It's in very good shape considering its life span, however there are many sections of track which aren't perfectly level. My bogies' wheelsets have low flanges, which strongly react to such imperfections. Fortunately, the solution is quite easy: Giving the bogies' mountings a bit of play allows for a three-point bearing which reduces the risk of derailments.

Lesson #3: Couplers on bogies have their merits
Not just the imperfections mentioned in lesson #2, but some gaps in the frogs of some points (switches) and other challenges of the trackwork resulted in many derailments over the day. From which I've learnt: bogies like to be guided.

If the couplers are mounted to the waggon's frame, the bogies have to find their own path and tend to run their flanges against the rails more often. At older frogs or other demanding spots of track this leads to the first wheelset riding up the rails. If however the couplers are mounted to the bogies, the latter are guided into the following curve by the leading vehicle and appreciably gain in better tracking.

Lesson #4: Huzzah for variety
OK, this is more of a lesson which my friend has learnt. Since we both vowed to hold several operation sessions a year, he expanded his layout to some extent.

Since the garden has to have room for the family, he achieved a nice tradeoff: the fixed layout ends at a yet-to-finalize bridge crossing the pond and therefrom portable track is laid as needed.

Mix of portable track and fixed layout.

Thus a new layout can be realised each time and we have lots of room to experiment with. It also nicely fits into another idea of mine, but that's not official, yet.

Lesson #5: Shunting with a chain needs a winch
I've found many good uses for the chain fixed to my N°1. Especially towing waggons while running in reverse. However, it's remarkably tedious if one has no control over the chains' length. So, I'm planning a bricolage for next week to improvise a winch.

Country: France | Posts: 104 Go to Top of Page

Michael Hohn

Posted - 12/16/2020 :  09:21:54 AM  Show Profile  Visit Michael Hohn's Homepage  Reply with Quote

Looks like fun. Are you planning any changes to your flatcars, such as going to couplers mounted on the bogies?


Country: USA | Posts: 6993 Go to Top of Page

Engine Wiper

Posted - 12/16/2020 :  3:25:00 PM  Show Profile  Visit BreizhSteamer's Homepage  Reply with Quote

I'm indeed going for bogie-mounted couplers. It surely is a trade-off, sacrificing prototypical looks for operational safety, but as long as I don't have my own layout asking my friend to "fix his blasted trackwork", doesn't seem like an option, now does it?

More to come shortly.


Edited by - BreizhSteamer on 12/16/2020 3:26:37 PM

Country: France | Posts: 104 Go to Top of Page

Michael Hohn

Posted - 12/16/2020 :  3:59:30 PM  Show Profile  Visit Michael Hohn's Homepage  Reply with Quote
Wise choice. Fidelity in friendship is more important than fidelity to prototype.

Country: USA | Posts: 6993 Go to Top of Page

Ray Dunakin

Posted - 12/16/2020 :  11:53:57 PM  Show Profile  Visit Ray Dunakin's Homepage  Reply with Quote
Nice work on the flatcar, and the tips you posted are very helpful.

Country: USA | Posts: 3359 Go to Top of Page

Engine Wiper

Posted - 12/17/2020 :  05:08:51 AM  Show Profile  Reply with Quote
Nice work


Country: France | Posts: 205 Go to Top of Page

Frank Palmer

Posted - 12/17/2020 :  10:05:04 AM  Show Profile  Visit Frank Palmer's Homepage  Reply with Quote

Frédéric, nice to meet a fellow Fn3 modeler. Very nice attention to detail on the flatcar.


Country: USA | Posts: 6080 Go to Top of Page

Engine Wiper

Posted - 12/20/2020 :  07:29:33 AM  Show Profile  Visit BreizhSteamer's Homepage  Reply with Quote
Ray, JG(?), Frank, thanks for your kind words.
I sure hope that I can keep it up to the very end, I've never tried to detail the underside of a waggon before, so there's some uncharted territory for me.

Mike, true!

Edited by - BreizhSteamer on 12/20/2020 07:30:03 AM

Country: France | Posts: 104 Go to Top of Page

Engine Wiper

Posted - 12/24/2020 :  02:08:55 AM  Show Profile  Visit BreizhSteamer's Homepage  Reply with Quote
Our Summer Operation Session was a lot of fun, but most of all it was informative. I learned three very important lessons concerning my flatcars:

  • Frame-mounted couplers need large radii

  • Bogies need clearance for operational reliability

  • Bogie-mounted couplers increase reliabilty

Alas it came to light, my test waggons are way more forgiving than the rigid frame of an actual flatcar: even with R3-radius curves (2,390 mm of diameter, no less!) I struggled to move the waggon without any derailments. There are three reasons to it:

The obvious one is that frame-mounted couplers can only marginally swivel. So one needs large radii. Since I'm going to operate my trains on other people's layouts most of the time, I can't just expect the tracks to accomodate my waggons. So the waggons will have to adjust to the layouts.

Not quite as obvious is the fact that the bogies mustn't be fastened too tight. One has to allow for some play to compensate for the tracks' imperfections. That adds up to a three point support. If one ignores this requirement, the wheelsets are lifted off the track and due to the low flanges derailments follow quickly.

Lastly, there's one thing that I hadn't figured out before: Mounting the couplers to the frame means that the bogies have to find their own way. When entering a curve, the first wheelset is displaced laterally, the resulting torque turns the bogie into the curve. Just another challenge for the low flanges. Mounting the couplers to the bogies ensures that the leading waggon guides the bogie, which is literally pulled into the curve. Thus derailments happen far less often. That's a new one to me!

It can't be helped, as long as I don't build my own, perfectly constrcuted layout, the couplers have to be mounted to the bogies. But what about the height of the couplers? Fortunately it turns out that I can simply flip the mounting boxes. The couplers lose only a few millimeters in height compared to the frame-mounted option and I can live with that!

Proof of concept: the knuckle couplers can be mounted to the bogies at almost the same height.

Of course the couplers can't just be fastened with one flimsy screw. So a reinforcement is in order, made from small blocks of red cedar. The prototype would sport the draw timbers at this place, so I don't have to overstrain the modeler's license.

First try on draw timbers.

The first static test finds the construction to be somewhat plausible and the mounting boxes can now be fastened to the draw timbers. That will make sure that tension and thrust are passed on without building shearing forces on the mounting boxes.

The draw timbers underneath the waggon.

As a consequence the bogie mountings are suddenly becoming very important, in case of doubt the whole consist will tug at those. Until now, I've used simple woodscrew of 3 mm diameter, that won't do no more. First off, the body bolster's boring is enlarged.

The body bolsters' are drilled to fit M5 threads.

This boring receives an M5 thread. This thread is then hardened using superglue, quite a neat trick I've learned from constructing model aircrafts. Why M5, you ask? We'll come to that.

The M5 threads are tapped.

Since Piko's bogies are cast from plastic, they won't withstand the sharp edges of a threaded screw. These bogies have a boring with a diameter of 6 mm; they are supposed to receive a 6 mm king pin, which is secured with a washer and plasticscrew. I'm flipping the concept: The boring will receive a brass bearing bushing with a wall thickness of 0.5 mm.

A brass tube with 6 mm outer diameter and 5 mm inner diameter is cut to length.

This bearing bushing is pressed into the bogie. Of course, now there's only room for a M5 threaded screw which can't damage the plastic bogie any more.

The piece of brass tube serves as bearing bushing to protect the bogie from the screw's threads.

The bogie is being mounted with a stainless steel M5 Allen screw. The lesson learned during the operation session is applied and some play is allowed so that the flatcar keeps contact to track on less-than-perfect layout sections.

The bogie is being mounted with an M5 screw.

A short test run on some snap track shows that these adjustments bring good results. So it's definite that all my waggons will be constructed with bogie-mounted couplers. And I can later convert them to frame mountings, if I ever get to build my own layout.

And once more it just shows that one has to make compromises. However, I can happily live with this one.

Country: France | Posts: 104 Go to Top of Page

Engine Wiper

Posted - 12/30/2020 :  1:28:41 PM  Show Profile  Visit BreizhSteamer's Homepage  Reply with Quote
Hey folks,

could I trouble you for some quick feedback?
My flatcar's drawings suggest four stake pockets, that's six and a half feet between two stakes.
Would you call that sufficient, or should I go for more?

Thank you very much,


Country: France | Posts: 104 Go to Top of Page

Engine Wiper

Posted - 01/09/2021 :  04:20:15 AM  Show Profile  Visit BreizhSteamer's Homepage  Reply with Quote
Come on guys - no ideas on the number of stake pockets?




Country: France | Posts: 104 Go to Top of Page

Michael Hohn

Posted - 01/09/2021 :  06:01:06 AM  Show Profile  Visit Michael Hohn's Homepage  Reply with Quote

Yes, that seems the right number, based on prototype plans and photos.


Country: USA | Posts: 6993 Go to Top of Page
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