Boiler Designs?

[Shiva]

 Nice! + wait, what's the part number for the hatch wheel?

@Sven J  I forgot, that brown plate, replaced with plate rounds too. Brown plate replacement would keep the neck thingies at place, whle the other plate rounds would be oriented the other way. And all those kept in place regarding to each other with hose rigid. The blue plates would keep the upper and lower in place regarding to each other.

[Sven J]

1 hour ago, Shiva said:

I forgot, that brown plate, replaced with plate rounds too. Brown plate replacement would keep the neck thingies at place, whle the other plate rounds would be oriented the other way. And all those kept in place regarding to each other with hose rigid.

I understood it exactly that way
Problem is, when you build it like that, you don't have those long plates any more running through from back to front, so the whole thing might be more prone to bending.

1 hour ago, Shiva said:

what's the part number for the hatch wheel?

It's the steering wheel from the classic 3829 assembly,  mounted on a 20482 round tile instead.

[zephyr1934]

15 hours ago, Sven J said:

@zephyr1934 The solution you describe above is exactly what I had in mind first. But that 1/2-plate "steps" in the corners looked ugly. Then I had the idea to fill those gaps with neck bracktes and had to find some way to attach them...

Btw: Here's the first real-life build that uses the proposed design.

I agree about the ugly gaps and the final version looks great!

[Shiva]

1 hour ago, Sven J said:

I understood it exactly that way
Problem is, when you build it like that, you don't have those long plates any more running through from back to front, so the whole thing might be more prone to bending.

It's the steering wheel from the classic 3829 assembly,  mounted on a 20482 round tile instead.

Ahhh, wouldn't the red plates be enough?

Ohh, nice hack/mod :)

[Sven J]

36 minutes ago, zephyr1934 said:

the final version looks great!

Thank you!

20 minutes ago, Shiva said:

Ahhh, wouldn't the red plates be enough?

Well, I haven't tried yet. But I suspect that, at least for longer boilers, they may not suffice. I like to have as much stability as possible ;-)

20 minutes ago, Shiva said:

Ohh, nice hack/mod :)

Thanks, but it's actually not my own invention to use the steering wheel this way. Several train MOCers have done so before.

Edited March 25 by Sven J

[Shiva]

Ahh :) Some of the loco's in my to build wishlist, would have use of those.

[sergiomonai]

On 3/23/2026 at 9:49 PM, Sven J said:

Hi all,

sorry for bumping this topic, but I thought it might be of general interest.
For an upcoming new steam locomotive, I needed a boiler with exactly 5 studs diameter. So I invented a rather weird design I'd like to share with you.
Characteristic elements of this design are: the "backbone" made of Modified Bricks 4733 with Rigid Hoses (cut to 4.5L) running through; the relatively new oval 1x3 plates whose open stud holes are used to attach them to the ends of the Rigid Hose pieces; and finally the inversion of stud orientation in the sides, using the old hinge plates.
The result is surprisingly sturdy.

Best regards,
Sven

Hallo Sven

do you remember my ideas for the never realized boiler of the TkZ226?

 

 

 

I think it could be adjusted to odd measurements

Sergio

 

[Sven J]

Hi Sergio,

great to hear from you again!
What happened to your previous EB account?

Yes, I remember, and this is probably quite a flexible design with regard to different diameters.
Problem is, how can it be closed at the front without gaps?

Best regards,
Sven

Edited April 16 by Sven J

[sergiomonai]

Hi Sven

Since I've not used my account for a longtime, the ancient e-mail was no more active so had to change my profile data. As regard your acute observation this is upon your desired diameter, for my project there were in fact residual voids (LEGO doesn't produce many odd stud pieces). Since, as you know, I'm not a purist, I was imaging to put a heavy black cardboard (or a self made sheet of black plastic dish) between the frontal door and the boiler body. 

regards

Sergio

[zephyr1934]

21 hours ago, sergiomonai said:

Hi Sven

Since I've not used my account for a longtime, the ancient e-mail was no more active so had to change my profile data. As regard your acute observation this is upon your desired diameter, for my project there were in fact residual voids (LEGO doesn't produce many odd stud pieces). Since, as you know, I'm not a purist, I was imaging to put a heavy black cardboard (or a self made sheet of black plastic dish) between the frontal door and the boiler body. 

regards

Sergio

Oh, that's nice! On many American steam engines the boiler had an insulating jacket (typically asbestos) that was then covered with sheet metal while the firebox was not insulated, resulting in a slight decrease in diameter from the black sheet metal over the boiler area to the uncovered smokebox that was often simply painted with a mixture of graphite and oil to give it a gray look. If your prototype similarly has a non-insulated smokebox you might be able to step down to a narrower smokebox to hide some of the gaps

[Darkkostas25]

Someone used a new round clip piece Plate, Modified 2 x 2 with Bar Frame Round : Part 7068 | BrickLink   for boilers?

[Stereo]

They did add this ~5 stud piece (1mm larger) Wheel 68327 in the time since this thread started, in some situations it could be helpful to transition down to regular 4 stud round parts as they fit in the hole.

[FGMatt]

I went pretty simple:

The orange parts are all inverted brackets, you can swap them out for regular brackets on the places where the mounts are. The whole thing is basically held together by 4 x N plates (shown in blue), which can overlap to join together any section length. It gives a roughly 6 stud wide tube, so it can be capped with 6-stud diameter circular parts.

[sergiomonai]

On 4/18/2026 at 7:47 AM, zephyr1934 said:

Oh, that's nice! On many American steam engines the boiler had an insulating jacket (typically asbestos) that was then covered with sheet metal while the firebox was not insulated, resulting in a slight decrease in diameter from the black sheet metal over the boiler area to the uncovered smokebox that was often simply painted with a mixture of graphite and oil to give it a gray look. If your prototype similarly has a non-insulated smokebox you might be able to step down to a narrower smokebox to hide some of the gaps

Hi, thank you for the information, it adds a bit of reality to my design, when the time of building will come...

[Sven J]

@zephyr1934 & @sergiomonai: I think that insulating jacket was common not only in the US, but quite everywhere (though, in later years, at least German railways used glass wool  rather than asbestos).

However, on many European steam engines the diameter of the smokebox was larger than that of the boiler proper -  just by the amount that the insulating layer added to the boiler diameter, in order to achieve a clean look.

Having said that, on old Prussian engines the smokebox had a considerably larger diameter than the boiler even with its insulating jacket included. This was to gain more space for the superheater equipment, but later turned out unneccessary.
 

Edited Tuesday at 08:44 PM by Sven J

[zephyr1934]

2 hours ago, Sven J said:

However, on many European steam engines the diameter of the smokebox was larger than that of the boiler proper -  just by the amount that the insulating layer added to the boiler diameter, in order to achieve a clean look.

Interesting. There were several US steam locomotives where they extended the jacketing over the smokebox for a smooth appearance too (e.g., the Milwaukee Road 261), but I think on those engines the actual smokebox was no wider than the actual boiler.