[noiseboy]

We're planning an over-ambitious OO layout in our son's small bedroom. It's a little tricky to describe, but the centrepiece is a mountain.

Imagine a basic oval sitting at one level above ground, 3rd degree radius with 2 r600 straights on one edge and 2 points on the other. This is the outside of the layout. Into one point goes an incline which wraps inside the oval on its way down (2nd degree radius) and out the front to a station along one wall - the overall shape is of a question mark. Out of the other point goes an inside rise - currently I'm thinking this could lead to a semi-helix construction, which would join the path of the rise on its way up on the storey above. It would make a half-turn with the track underneath. This semi-helix would ultimately be under the mountain, then the top level come out on top and peel off. This should (if I've worked it out right) be slightly inside the 3rd degree radius, using a combination of bridges and side-of-mountain stuff. It then makes a final 3/4 circle, flying out sideways along another wall of the bedroom. That is all probably inexplicable.... sorry!

I've done some incline tests on this idea using rough supports and the trains can make it up and down reliably, it seems. The problem now is the practical one of how on earth to construct it, if it is possible - the margins are super-tight all round.

My current thinking is to build effectively a 2nd baseboard above the first, which is just a perimeter and hollow inside. This would be the first level. I guess I could use any rigid material for this - the base is 18mm chipboard with a nice 50cm diameter hole in the middle for access, I guess 12mm chipboard for level one would be fine (I'm put off mdf because of track pins). But how to construct the ramps? I guess plywood is best here - what thickness? 6mm? Also, what sort of support? I had a look at the Noch helix which looks like a great design, but not quite the right dimensions in our case. Is it possible to make these kinds of supports and DIY?

All help and advice appreciated!

 

[Wallaroo]

Hiya,
I have recently been looking at Helix's for a new layout, to feed the storage tracks and to gain height to cross the bietshtal bridge. Have just about completed one for N scale. I found some very useful information at the following sites, although in German if you use the google translate page it does a pretty good job...

http://64.233.189.101/translate_c?hl=en&am...5TjTgnpQH8B968A

The site has an excel document that you can use to calculate the board sizes and you can input your own track radii in the 2nd tab 'gleise'. Do some tests using paper sections to check sizing with the tracks etc.

I had looked at the Noch units but they are way too expensive ( i think around $180 for 1.5 turns downunder) so for about 1/3rd of that i have 5.5 turns dual track N.

cheers

Jeremy

 

[dwb]

Try this topic for a brief discussion on spirals about 18 months ago.

David

 

[alastairq]

what is the overall shape of the layout's baseboards?

dimensions overall will help.

[for example, is it a rectangle?

or will it go ''around the walls?'']

 

[zmil]

The Helix topic and link is probably one that could be added to the FAQ page (yet to be created)

Regards

Zmil

 

[noiseboy]

Thanks to all for the links and advice thus far! Good tip re trying out things with paper, by the way.

The baseboard is weirdly shaped - the mountain section is approx 1.2m x 1.4m (with one curved corner to follow the line of the track). If you imagine that in a corner of a room with the 1.4m against the long wall, there is another 1.6m x 0.5m in one direction for station and sidings, then at the top of the mountain another extension will go out on the shorter wall to a smaller station at the top.

Had a chat today with a relative who is very good at construction who thought that the chipboard / plywood combo should work well. He suggested threaded bolts to form the basis of supports, drilled through the baseboard (we'd also need to drill 2 holes through metal strips to support the plywood itself). How does that sound to everyone?

 

[dwb]

QUOTE Had a chat today with a relative who is very good at construction who thought that the chipboard / plywood combo should work well. He suggested threaded bolts to form the basis of supports, drilled through the baseboard (we'd also need to drill 2 holes through metal strips to support the plywood itself). How does that sound to everyone?

Sounds good to me. The trick is to get a combination of gradient and curvature that your trains are comfortable with and to keep the gradient even.

David

 

[noiseboy]

QUOTE (dwb @ 11 Jan 2009, 19:09) <{POST_SNAPBACK}>Sounds good to me. The trick is to get a combination of gradient and curvature that your trains are comfortable with and to keep the gradient even.

David

It's a bit of a black art, isn't it?! When testing, one route up (the one I'm using) seemed to be a piece of cake, the other that on-paper was no more difficult proved impossible.

Is there a best received wisdom on getting into and out of gradients? Should they be relatively abrupt or more gradual? Or is it (again) simply suck it and see? I have a set of points at the top of the hill, and instictively I felt I should have the track flat and straight going into them, which seemed to pay off - I got a very good speed roaring up (and down) the hill and safely across the points in the end doing it that way.

I've been experimenting a little more today, and think I can make construction a little easier by actually having three levels across one quarter of the helix under the mountain, and then running the exposed track in tiers without any criss-crossing as originally envisaged. Things line up a whole lot easier which should make the whole process less painful!

In the very very long term, after all this has finished, I'm wondering about adding a rack railway, but that might be for another thread!

 

[dwb]

QUOTE Is there a best received wisdom on getting into and out of gradients? Should they be relatively abrupt or more gradual?

I can think of two problems which need to be avoided

1) Grounding of long wheelbase vehicles when the transition is too sharp

2) Vehicles becoming decoupled if the angle between them is sufficient to allow the coupling to slip out. This is not usually a concern for the Hornby / Bachmann hook and bar style coupling but it does matter to me as I use Kadees.

Basically "smoothly does it" is the motto. Allowing a stretch of "calm" track before points is definitely a good move.

David

 

[Edwin]

Also a good idea to have the vertical curve (change of gradient) on a piece of track that is not also curved horizontally.

 

[barrymx5]

You may find the following helpful - I did!!

Designing and Building Multi-Deck Model Railroads
By Tony Koester
Softcover; 8 1/4 x 10 3/4; 96 pages; 175 color photos;
USD 19.95 by Model Railroader

 

[noiseboy]

Thanks guys!

 

[Brian Considine]

Helix's are a very useful way of gaining height in a small area - very popular in mainland Europe which is one of the the reasons why most European locomotives can haul far, far more that needed on the reasonably straight & level.