Has anyone build a base plate anchored train spiral?

[Afolomus]

Hi guys,

I'm planning a Lego diorama with a mountain range. Within one of the mountains I plan to place a lego train spiral. Heights and height differences make train mocs just pop. Do you have examples of how to build a train spiral anchored to base plates (imagine 4 48x48 plates)?

To my amazement I couldn't find a single example on google images: Noone builds train spirals on base plates. All spirals fall into three categories:
1) The tracks are on a nonlego structure, mostly wooden supports.
2) The tracks are on a lego structure, but that structure is not on studs, but flat ground.
3) And the third one is this crazy outlier that uses Lego bending: http://www.nalug.org/TrainShow2006/Spiral/spiral01bm.jpg

And when I entertained the idea, I came across a possible problem. If you change a circle to a spiral but you only have the same length, you change the diameter/radius. Does this change the layout or puts the entire structure under so much stress, that it's simply problematic to set up?

Calculation:
Imagine a classic circle based on curved tracks. You have a radius of 40 studs/32cm or a diameter of 80 studs/64cm. If you abstract it as a string you can imagine it as a flat circle or with an incline. This leads to two states:
Flat track:Circumference 201 cm
Spiral:Height (12 bricks equal) 11,52 cm, Imagine unwrapping it while keeping the incline. Then you are left with an easy pythagorean theorem with a hypothenuse of 201 cm. This leads to a circumference 200,67 cm.

This leads to a difference of 1,08 mm (1 stud equals 8 mm) in diameter. This leads to some stress I might want to mitigate by not anchoring the entire structure, but not to changing the layout (going down a stud in diameter or something along those lines.

Hope you can help, greetings Afolomus

[Toastie]

22 minutes ago, Afolomus said:

This leads to some stress I might want to mitigate by not anchoring the entire structure, but not to changing the layout

Just do it. Honestly. Your calculations are perfect.

LEGO bricks, plates, tracks ... are much more relaxed than any calculation tend to predict. Look at that totally illegal #3 bending example (as in: Have fun with it!).

Much more importantly: Keep the track elevation such that a train can actually climb it.

Nice project!

All the best,
Thorsten 

 

 

[Afolomus]

Thanks for the reply :)

Regarding the elevation: 12 Bricks in one spiral is the minimum I've got from testing. The linked example picture runs with 15 bricks per rotation, so I'm optimistic about it working.

Greetings, Afo

[Polarlicht]

How long are your trains? I can barely even drive with the full Santa Fe train with two PF train motors on an incline of like 3m length and 20cm height difference.

[Vilhelm22]

Also how much space are you allowing at the base?  Are you doing R40s only or can you go bigger?  At an extreme (though I realise basically nobody has space for this in their personal layout) scale, Monty Smith in the LGMS Facebook group proposed an R120 spiral, with 1 brick/segment.  Of course by going for larger radius you can a) reduce the gradient allowing for smoother ascent/descent with less power required or b) reduce the number of spirals.

The totally nuts option would be to use flex track!

[XG BC]

in terms of stress just look at masao hidakas and the monorails discussed in our CRS topic:

the curves of that masao hidaka type monorail are entirely constructed using stressed bricks. lego has more tolerances than youd think.