medium size helix (30"-36" radius) questions


M

Mattchu60

Member
Hello all,

I am in the planning stages of my layout building. The layout will be a folded dogbone style, in a 10.5' x 19' room with 30" minimum radius curves. I think I am getting close to settling on a track plan, which is pretty hard as I keep changing my mind.

One thing that keeps coming up is staging/yard. I would rather have my layout be about scenery and industries than having a yard gobble up half of it, but I still need a place for storing trains. I would like to build a 2nd deck below the layout for staging.

For this, I will need a helix. I would be looking at a curves for it somewhere between 30-34" radius. I'm concerned about getting trains up this hill. I dont plan to run more than 2 units in a consist ever. Will be a mix of steam/early (2 axle) diesels for power.

What kind of grade would I be looking at? Any tips on how to build one of these? How much space should I allow between decks?
 
Mattchu60 said:
For this, I will need a helix. I would be looking at a curves for it somewhere between 30-34" radius.

What kind of grade would I be looking at? Any tips on how to build one of these? How much space should I allow between decks?
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I think there are several good threads on building a helix. The ones I like best are those that have threaded steel rods with bolts holding the decking in place. the bolts can be twisted to make minor adjustments in the height of the decking.

I usually say one needs 3" of clearance for HO. Then add the thickness of the decking and road bed so say 3 3/4".

circumference = pi x diameter so 34" x pie = 106.8" x 2 = 213.6"
Going up 3.75" in 213.6" (3.75"/213.6") looks to be a 1.8% grade.

30" would be right at 2%
 
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JFYI it's pi not pie, regardless of the kind of pie (apple is my favorite).

I decided not to build the helix I needed so I contracted with:

http://www.ashlintrains.com

to build two of them for me.

Very pleased with the result despite a bit of miscommunication at the start. I told them I wanted a 4" rise per turn, which I measure from sub-roadbed-top to sub-roadbed-top. They measure (or did) sub-roadbed-top to sub-roadbed-bottom.
 
helix

dstern350 said:
Have you seen any pictures of the bolt setup that you describe?

Thanks
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I have some picture of the threaded rod setup for a helix on my website found here. I used 1/4 -20 all thread from my local big box store and 3/4 in washers. There are nuts on both top and bottom of the helix pieces. I used 90 degree sections of 5mm (~1/4 in) Laun plywood laminated together for total thickness close to a half inch. There are 16 all thread rods supporting the helix. I use a spacing block and a level set to my grade to verify that each turn is the proper height.
 
dstern350 said:
Have you seen any pictures of the bolt setup that you describe?
Click to expand...
observation.JPG

trainbowl.JPG
 
Stoker said:
Keep in mind that you can get all-thread rod in the electrical department (hanging rod) in 8'-10' lengths for a fraction of cost per foot of the 3'-4' pieces in the structural steel bin.
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Interesting. I'll have to keep that in mind.
Brian
 
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