Helix within a Helix

[Rusty Spike]

I have a 12 x 7 space in a room adjacent to the train room where I'd like to stage long trains (30 cars - 2 and 3 engines).

I'm giving thought to a double track helix going down 3 or 4 loops and a single track loop within that coming back up. I'm trying to maintain 32 inch minimum radii.

I need it run flawlessly so I don't have to switch rooms to re-rail, etc.

I've never done a helix and wonder what the usual things to watch out for are and I'm requesting feedback on the concept of a helix within a helix.

Thanks.

 

[LoudMusic]

Wow, opposite direction helixes one inside the other? That's ambitious

Sounds like a really interesting way to stage long trains in a relatively smallish location, virtically. I would make as much use of that 7' wide space (36"+ radius) to give yourself as much room as you can get for the supporting benchwork - it's going to get really busy in the lumber department.

Also, if you're going for flawless operation I would go to the ceiling with it. You plan to not have to touch it anyway, might as well make as much use of the concept as you possibly can. You could also put in crossover switches at virtually every helix intersection, allowing you to turn around and come back down (or up?) at any half loop.

The only problem that comes to mind immediately is the added stress on the units / couplers. They'll be sitting on a relatively large incline for prolonged periods. Surely that can't be good for them. And if there's a failure, it's high speed havoc at the bottom.

I too have never built a helix, but I have spent countless hours theorizing on interesting design concepts like yours. Fun fun. Best of luck to you - and I'd LOVE to see pictures if / when it ever comes to fruition.

 

[Gary Pfeil]

It seems to me that having a second helix inside another is more complication than needed. When you get to the bottom, what will the track arraingement be to get you turned around and headed back up? I would think you need another loop of equal radius, no? If so, it seems easier to make the helix 3 tracks, all on the same roadbed. I would use one track (the inside one) to go down, and two to come back up, and use these 2 tracks for staging. Here is a photo of my 2 track helix, when the bottom is reached, the two tracks seperate, and are connected together by another loop. In my case, this "return loop" is multi tracked and serves as staging, but a third track on the helix would serve the same purpose. A thought: I've experienced coupler failure with some of the plastic couplers which come on the Proto2000 freight cars when I've staged them facing downhill. This because they seem to have memory and after being pushed into each other for awhile, they tend to stay "open" and uncouple when the slack is run out. I replace them with Kadee, but if you stage facing uphill this problem is avoided.

Regarding construction, there are many ways, I had access to a lot of 3/4" plywood shelves. Each one provided me with 1/4 of a circle. I routed opposite sides of each end of each piece, and glued and screwed them together to save depth (and make the grade less) I ripped 2x4"s to 2x2 and nothced them to accept teh 3/4 " plywood, using them to maintain the clearance between levels. I started with 3 sections, laid the track (take your time and do your best work!) then added 3 more sections, and so on.

Oh, the photo will follow on the next post, as I used quick reply!

 

[Gary Pfeil]

Here is the photo

 

[Gary Pfeil]

Oops, never mind my previous comments, I get it now. You could come down the inside helix, widen the radius at the bottom and return on the outer helix. For some reason I couldn't conceptualize it earlier. And a 7x12' room ought to give you enough room to level out at the bottom and start to rise. Are you able to go around the walls, or is there an entrance to the room that must be left open? Will you just duck under for access?

I would start at the bottom and build the transistion in grade first. My thought is that I would use 2x4s notched as in my photo between the two helixes, once I knew the offset of the notches needed on both sides, it is easy to mark where the notches will be on a bunch of 2x4s. I set a table saw blade to 1/2" and made several cuts next to each other to make the notches. They will all be the same distance apart to maintain a steady grade and even seperation of levels. By tapping the roadbed into the notches (a snug fit) you have made an even grade easy. These vertical uprights with notches can be attached to the wall on the wall side, and legs can be added to the inside.

One thought I just had was that the rearmost helix will be difficult to get at when you do have a derailment, as the opposite helix will be in front of it. However this may not be too serious as the large amount of room will allow a very gentle grade, and by increasing this grade a bit a healthy seperation should be possible, helping access.

Good luck!

 

[LoudMusic]

Has anyone ever seen / made a helix that goes around the outer walls, which the operator stands in the middle of? It would definitely require some sort of duckunder stepover situation, but it would give a completely different perspective to the whole thing.

 

[Triplex]

There's a plan in the Oct 97 Model Railroader that uses linear staging on an inside-outside helix, very much like your idea.

 

[planeshavings42]

Gary, I'm Highly Impressed with your hilix

Here is the photo

:thumb:Hello, Gary, I was just checking out some older threads, and came across this, and am V E R Y impressed with your helix, do you by chance remember the cut angles for the ends of your circles, I plan to build two 6 ft helix with approx. 16ft straight run between them, going up on end, and coming down the other. I also plan to have two track's on each. Any help would be appreciated. Duane Hampton