[MOC] GWR Olton Hall (Hogwarts Castle)

[EWay]

My second train MOC, completed about a month ago, and my first attempt at a steam locomotive.

I present to you Great Western Railway locomotive 5972 “Olton Hall”, otherwise known as Hogwarts Railways locomotive “Hogwarts Castle” - the loco which pulls the Hogwarts Express.

It's a subject that's been MOC'd many times before, but I've always loved the look of Hall, Castle and Manor class GWR locomotives so my first attempt at steam was always going to be one of those, and I figured if I'd be bringing it to shows from time to time, a familiar locomotive would have the most appeal. That being said, now it's built (it's quite fragile) I'm terrified to take it out of the house... so it remains to be seen whether it will ever actually go to a show!

Purists look away now. This uses BigBenBricks XL driving wheels and a Circuit Cubes motor and bluetooth battery hub. It's my first experience with these third party products and I'm delighted with them both. The motor sits inside the firebox of the locomotive. It’s connected by a wire to the tender – lift up the coal section and the battery hub is sitting inside. The app to control it leaves a little bit to be desired, and documentation is almost non-existent, but at least in theory apps can be updated and, last time I checked, supposedly more documentation was due to be released in “spring 2022”.

This was a challenging build at every stage. Designing a steam engine in stud.io means you can’t test its running ability, and it turns out that significant tweaks were required. Various parts of the MOC were just plain difficult to put together. The driving wheels are connected by gears, but the gears have to be lined up with exactly the right teeth so that the holes on the wheels line up to connect the connecting rods. The boiler is flimsily attached and difficult to put back together if it comes off, often requiring major surgery.

Even sourcing parts was tricky – two half-cylinders in dark red, which have only ever been released in one set, a dark red 1x2 1x4 bracket released in two sets (but one is a polybag, and the other one is a special edition 200 piece bucket so rare that there’s only 1 listed on Bricklink!), dark red windows which have only appeared in two sets… these were among a dozen or so parts with 400 sellers or fewer on Bricklink.

I also experienced three part breakages, which I can’t ever remember happening to me before, due to brittle dark red. The worst instance was one of those rare dark red windows, which broke across the bottom as soon as it looked at another piece. Fortunately I was able to glue that one back together (I recommend Loctite All Plastics Super Glue) – you can barely see the crack and it’s got perfect clutch.

Once I’d built the tender, I discovered it wouldn’t go round Lego curved track – I didn’t think it was long enough to matter originally. Thankfully it wasn’t too hard to modify it to have the back two axles on a turntable. It’s not even that noticeable when it’s running that they’re slightly articulated. Getting the front bogie to turn without hitting the cylinders was much more difficult and I had to experiment with several different configurations before I got it working.

The cylinders are possibly my favourite part of the model. It took a bit of ingenuity to attach them at this angle, especially since they are studs out at both ends, but I think these pieces capture the shape of Olton Hall’s cylinders perfectly.

I won’t say too much about the boiler since I borrowed very heavily from BritishBricks (and also Andrew Harvey, who I believe deserves credit for the original sloped boiler idea). At least the section behind the dome is my own work – getting a section 2 studs long to replicate the curve of a half cylinder on its side is very tricky, and it’s the part of the model I’m least happy with, but I don’t think it’s any worse than the alternative, which would be to use cheese slopes to approximate the curve. Unfortunately SNOT macaroni bricks aren’t an option, because you’d also need 2x2 macaroni plates to get the right height (or a 2x4 semi-circular plate), and such a thing doesn’t exist.

Another feature I’m particularly pleased with is the coupling between the engine and the tender. Getting it to navigate R40 curves (quite a feat in itself) means that if I used a simple pivot between engine and tender (e.g. train magnets or a couple of 3176 Plates, Modified 2 x 3 with Hole connected with a pin), the tender would collide with the cab unless there was a huge gap between them. I spent ages trying to come up with a method whereby there would be a short coupling that would naturally extend when going around corners to avoid collisions, and in the end what I came up with was extremely simple. I’m now going to vainly christen my solution the Eastaway Coupling :D It’s easier to explain with an image so here it is:

Inertia does the work of pulling the linkage to the side when needed. Unfortunately this doesn't work when driving in reverse (at least I assume, I haven't actually tried it). In reality the pin isn't fully inserted into the axle+pin connector - I needed an extra half stud of room to allow for handlebars at the front of the tender. Before anyone asks if the connection is strong enough to pull carriages being just an axle in an axle hole, I believe it is, but only because I tested 20+ different 2L axles in 20+ different axle+pin connectors to find the ones with the strongest grip. It's handy to have an extensive Technic collection!

The deviation from pure Lego has been a strange experience. I used some questionable building techniques – the top of the boiler is attached by fitting a half-cylinder over the studs of a bracket at a slight angle, the pipes that come down from the sides of the smokebox aren’t actually attached to anything, the connecting rods of the pistons are bent outwards very slightly (but well within the tolerances of a Technic half-liftarm pin connection). The purist in me is slightly uncomfortable, and I can see it’s a slippery slope, but I've set myself some ground rules, (e.g. I'll only use custom parts where there's no possible brick-built alternative) to keep myself (pardon the pun...) on track.

Edited May 17, 2022 by EWay
typo in body; forgot to add [MOC] in title

[ColletArrow]

She's another beauty, stunning work! I do enjoy pretty much anything GWR though so I might be biased

The sliding coupling is ingenious, I've seen similar systems on OO gauge models but your implemenation here looks neat. The cylinder shaping is fantastic too. Have you built a cab interior?

I am surprised that you chose to use CircuitCubes for power, and by the sounds of it just one motor, for such a large loco. How much pulling power does she have?

[EWay]

50 minutes ago, ColletArrow said:

She's another beauty, stunning work! I do enjoy pretty much anything GWR though so I might be biased

The sliding coupling is ingenious, I've seen similar systems on OO gauge models but your implemenation here looks neat. The cylinder shaping is fantastic too. Have you built a cab interior?

I am surprised that you chose to use CircuitCubes for power, and by the sounds of it just one motor, for such a large loco. How much pulling power does she have?

Thanks! I don't have any carriages yet so pulling power is yet to be determined... might have to add a second motor somewhere one day. I was struggling to find any other motor options tbh, as I wanted to try out the coupling and it wouldn't have worked if it was powered through the tender!

Here's a bit of cab interior detail:

Also there's a video of it running here: https://flic.kr/p/2nhtn9N

Edited May 16, 2022 by EWay

[Vilhelm22]

I’ve seen many renditions of ‘the Hall that thinks it’s a Castle’ over the years as well as the real thing and this is a brilliant one.  Great work @EWay on this excellent MOC!  Particularly as your first steam locomotive…

[Feuer Zug]

Well done. This is a shining example of the Hall class locomotives. The dark red really works better than any of the official LEGO models in regular red. Your solution for coupling the locomotive to the tender is interesting and ingenious.

[zephyr1934]

What a fantastic build, it looks amazing with lots of details. I can totally see what you mean about it being fragile, which comes from many of the details. Your experience with part availability is also spot on, you can't avoid it but with a bit of experience you learn to keep an eye on parts prices as you build (except when you don't and discover a common 2x2 plate is extremely rare in the color you're building) and when possible, come up with clever part substitutions to bring the costs down (e.g., a pair of 1x2 plates). I'm sure you will continue tweaking the build to keep the look while addressing whatever fragility. The tender coupling is brilliant, but I'd suggest you either glue the assembly together or replace it with a technic beam that cannot pull apart. Left on its own, it will wait until the least opportune moment to pull apart on you. Of course that means you have to find a half stud offset in the bricks, with the idea part substitution being a 1x2 brick with one stud on the side, but those only exist in white at the moment. With a little head scratching I bet a viable alternative could be found. At any rate, great work!

[Ropefish]

7 hours ago, EWay said:

This was a challenging build at every stage. Designing a steam engine in stud.io means you can’t test its running ability, and it turns out that significant tweaks were required. Various parts of the MOC were just plain difficult to put together. The driving wheels are connected by gears, but the gears have to be lined up with exactly the right teeth so that the holes on the wheels line up to connect the connecting rods. The boiler is flimsily attached and difficult to put back together if it comes off, often requiring major surgery.

I would offer a suggestion here, only gear the weighted driver set! this reduces the amount of gearing the train has to use as the drive rods do what they would do on a real a train, of course this would mean you will need a 3d printed drive rod to span the four drivers but ive found it makes operation much smoother due to less friction.

the tender connection  is a wonderful little thing, some O scale locomotives have a similar draw bar on them that allows the tender to pull out and to the side on curves but pull up close on straight track creating tension with a spring, I also love the piston cylinders very smart use of parts there and looks a lot better then the 3 hole thin lift arms!

[EWay]

14 hours ago, Ropefish said:

I would offer a suggestion here, only gear the weighted driver set! this reduces the amount of gearing the train has to use as the drive rods do what they would do on a real a train, of course this would mean you will need a 3d printed drive rod to span the four drivers but ive found it makes operation much smoother due to less friction.

It certainly would help, but where there's a purist Lego solution I prefer to use it!

[Ropefish]

11 hours ago, EWay said:

It certainly would help, but where there's a purist Lego solution I prefer to use it!

Totally understandable, i can respect that.

[Man with a hat]

Great build. It looks really good. And the cylinders indeed work out perfectly. I like the coupling solution. The principle is quite clever and I am sure a reliable/robust version can be made of it.

[XG BC]

looks very nice! you captured it perfectly. ingenious solution for connecting the tender and loco together.

[Paperinik77pk]

I add my appreciation together with all other members - very nice locomotive and very smart solutions (the cylinders are my favourite!!!) 

Ciao!

Davide