Help with HO Scale Helix design
#1
Hi guys, im looking for some help with a helix idea that i have. Im not good with measurements and such, so im hoping i can get some help from you guys Misngth

You might have seen my M&ET plans in the Layout Planning forum. Well im redesigning parts of it, its going to be part layout and part modules. It needs to be a double decker layout in order to bring the size of this massive project down, which i do not have a problem with and i think would make it more interesting.

If you have not seen the plan, you can see it here in THIS THREAD

The specifications for the helix are pretty simple.... i think LOL

~~I would like the helix to be 22 or 24" radius.
~~Single Track would be fine, but double track would be great, but it is not necessary....
~~Im thinking that the helix would have to travel 14" down to the bottom level, 14" between top and bottom level should be sufficient room for all structures while also leaving enough "sky" room
~~Not sure how much space would need to be between each spiral of the helix....
~~Anything else??? I know im missing alot of stuff for the plans lol

The reason i only need a 22 or 24" radius on the helix is because i wouldnt be running anything longer then a 60' car down to the bottom level.... The engines that i would be running up and down would be 70 Tonners, SW1500's, and Gensets so there fairly small locos and could handle 22 or 24" radius with no issues....

Im looking for any and all advice here on this helix design/plan. I know there is probably some stuff that i left out that needs to be known, so please ask away and feel free to post your thoughts. Thanks in advance Misngth
Josh Mader

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#2
Is it possible to run the 22" inside the 24" radius?

Here is a thread which is good for calculating a helix <!-- m --><a class="postlink" href="http://www.trainboard.com/grapevine/showthread.php?t=85383">http://www.trainboard.com/grapevine/sho ... hp?t=85383</a><!-- m -->
Tom

Model Conrail

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#3
Two questions:

1) how long do you expect your trains?
2) what is the thickness of your layout base?
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#4
tomustang Wrote:Is it possible to run the 22" inside the 24" radius?

Here is a thread which is good for calculating a helix <!-- m --><a class="postlink" href="http://www.trainboard.com/grapevine/showthread.php?t=85383">http://www.trainboard.com/grapevine/sho ... hp?t=85383</a><!-- m -->

Tom, Im not sure if a 22" radius could fit inside a 24", but i dont see why it wouldnt. 22" radius would take 44" to make a complete circle and 24" radius would take a 48" to make a complete circle, which should leave 2" between the tracks right? That would be sweet if i could do that....

Thanks for the link, ill have to check that out later tonight, im on my way out the door for a day at Disneyland with my girlfriend Misngth Misngth
Josh Mader

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#5
nachoman Wrote:1) how long do you expect your trains?

Hummm i guess thats a very important question lol. I suppose i would like to run trains down to the lower level between 10-20 cars.... All trains going down or up the helix would be pulled by 3-4 70 Tonners, 2 SW1500's, or 2 Genset locos, which is how the real M&ET moves freight on there tracks in the Beard Industrial District.


nachoman Wrote:2) what is the thickness of your layout base?

Im not sure yet, but im thinking ill be be using 1-2" blue foam. Most likely ill be sticking with the 1" blue foam, cuz thats what i can get (living in Cali) the stuff in the Tongue & Groove 2x8' panels. I might double up on the foam to make it a total of 2", i just dont know as of yet. Im thinking i would be fine with just 1" as the M&ET is on VERY flat land, and i have not seen much terrain except for minor changes around structures in such, in which i can just add foam below the layout/module and carve out.... So im going to say 1" foam for my base is going to be my final answer lol. 1" foam plus probably 1/2" ply if i use ply for the real base. I havnt decided on the actual construction of the layout section and the module sections yet....

If you need more info, i can certainly give it some thought and jot down my ideas about the construction of the layout and module bases....

Now the Free-Mo module bases would be a whole different story, but i dont plan on hooking any of the Free-Mo modules up to where the Helix would connect top and bottom levels so this shouldnt be so important right now.
Josh Mader

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#6
Josh, have you got any of your freight cars built, yet? I measured an f-unit and found it to be about 2.5 inches tall. I suspect your power units will be about the same height as an f-unit. Measure your tallest car, add an inch for clearance and the thickness of the table and track and you have the amount of elevation you need to gain on each rotation of the helix. You need to have the helix base strong enough to eliminate sagging. You can't use an "L" girder type of construction because the extra thickness of the "L" would increase the distance the helix would need to go up in order to clear. If you made your helix base wider, say an extra inch to inch and 1/2 inside and outside of the tracks, you could make it like 2 upside down "L" girders, in other words a "U" channel. In that case, the base could be kept thinner and flexier because the sides would stiffen the bench work.
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#7
If your trains are relatively short, have you considered a set of switchbacks as opposed to a helix?
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#8
Josh,

Minimum thickness for a module using 2" foam is about 4", including roadbed and track. The 2" foam is actually strong enough to be supported only every 24" or so. So a 2x4 module, built from nominal 1x3 (good pine, or ripped from 3/4" ply) with a cross bar in the middle is your basic building block.

Now if you want 14" between the surface of the bottom module, and bottom of the upper deck, you'll actually need to climb 18".

I also think that it would be better to have 2 1/4" between the tracks on a curve like that (see <!-- m --><a class="postlink" href="http://www.nmra.org/standards/sandrp/s-8.html">http://www.nmra.org/standards/sandrp/s-8.html</a><!-- m -->). SO you will have to go to 24 1/4" radius on the outside, or reduce the inner to 21 3/4".

Anyway, some calculations for your consideration:

Circumference = pi x diameter OR pi x 2 x radius

3.14 x 2 x 24 = 150" or 12.5 feet per complete turn for the 24" radius AND
3.14 x 2 x 22 = 138" or 11.5 feet per complete turn for the 22" radius

So that's 24 feet of track for each turn the radius makes.

Now you need to go up 3" with every turn (<!-- m --><a class="postlink" href="http://www.nmra.org/standards/sandrp/s-7.html">http://www.nmra.org/standards/sandrp/s-7.html</a><!-- m -->), but that's from the railhead. So call it 4" if you make your helix subroadbed out of something like 3/4" ply.

Grade% = rise / run x 100%
4"/150" x 100 = 2.6%
Don't forget that the inside will be effectively steeper, since there is less run.
4"/138" x 100 = 2.9%

Can you live with that grade? Since it is on a curve as well, the length of the trains will be quite restricted. The only way to reduce the grade is to increase the radius, since the 4" clearance is pretty much non-negotiable.

So going up 18" using a 4" climb with every turn requires 4.5 turns.
4.5 x 24 feet per turn = 108 feet of helix track.


Something to think about...! I hope it is helpful. I am going to put some other comments in your layout design thread too.

Andrew
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#9
One other comment - the tighter the radius, the more likely the train is to "stringline" and haul the cars off the track sideways, instead of hauling them along the track, which is what you want them to do. This may cause problems with the 60' cars on the steeper/tighter gradient. The only real way to find out is to try it out - but go for the largest radius you can fit in and keep the gradient as flat as possible, at the expense of increasing the number of turns
Found this which may give you an idea about space needed HO scale Helix model train elevation kit 2% *NEW ITEM* Item number: 360171276386
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#10
Josh, I think I would still mount the Modesto Yard on an elevator and forget the helix. You could build the yard bench work with thin plywood and foam for light weight, and then use a frame work made of aluminum angle to strengthen the entire assembly while holding the weight down. Install 2x2 stringers vertically on your wall studs, and mount the heaviest duty, ball bearing drawer slides vertically to locate and guide the yard up and down. Install a 3/4 inch threaded rod going through a nut secured to the yard benchwork. Put a pulley on the bottom of the threaded rod and a pulley on the end of a 110 volt ac motor mounted to the wall below the bench work. When the motor turns one way the threaded rod carries the yard up to the second level, when it is reversed the threaded rod carries the yard down to the lower level. Put a spring loaded switch below the bench work at the bottom and another one above the bench work at the top that is wired to the motor switch through the normally closed contacts at each end of the travel. You would power the motor through a double pole, double throw rocker type switch. When the yard is coming down and actuates the switch at the bottom, the switch would open shutting off the motor and shifting the power to the other side of the rocker switch. That would stop the yard from moving down further, but allow the rocker switch to start the motor in the opposite direction. The switch at the top of the travel would work just the opposite stopping upward travel but allowing downward travel. Make the two limit switches adjustable to allow you to align the yard with the layout. If you don't want to be switching high voltage, you could wire the motor through a contactor with the contactor activated by relays energised by the rocker switch.
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#11
While not the most inexpensive option, Ashlin Trains has a 22" radius helix that will do an 11" rise with 4" between levels. Might be able contact them for a custom size if you need another loop for a little more rise.

<!-- m --><a class="postlink" href="http://www.ashlintrains.com/servlet/the-51/railroad-model-train-ho/Detail">http://www.ashlintrains.com/servlet/the ... -ho/Detail</a><!-- m -->

My N-Scale helix came from these folks.

Just wanted to toss that out there as option as well.
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#12
Russ and Andrew, you guys are awesome!!

Russ, an Elevator would be interesting, and i like your idea. It would just be a matter of making it happen. The way you explained it doesnt sound like it would be that hard, but ill have to have my grandpa read it over, hes good with things like this, and he would be helping me build it, and i have a feeling he would understand it more then i am right now. Of coarse, i only read it one time, i usually need to read things like this a few times to understand everything, just how my little brain works LOL 35
Josh Mader

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#13
MasonJar Wrote:Josh,

Minimum thickness for a module using 2" foam is about 4", including roadbed and track. The 2" foam is actually strong enough to be supported only every 24" or so. So a 2x4 module, built from nominal 1x3 (good pine, or ripped from 3/4" ply) with a cross bar in the middle is your basic building block.

Now if you want 14" between the surface of the bottom module, and bottom of the upper deck, you'll actually need to climb 18".

I also think that it would be better to have 2 1/4" between the tracks on a curve like that (see <!-- m --><a class="postlink" href="http://www.nmra.org/standards/sandrp/s-8.html">http://www.nmra.org/standards/sandrp/s-8.html</a><!-- m -->). SO you will have to go to 24 1/4" radius on the outside, or reduce the inner to 21 3/4".

Anyway, some calculations for your consideration:

Circumference = pi x diameter OR pi x 2 x radius

3.14 x 2 x 24 = 150" or 12.5 feet per complete turn for the 24" radius AND
3.14 x 2 x 22 = 138" or 11.5 feet per complete turn for the 22" radius

So that's 24 feet of track for each turn the radius makes.

Now you need to go up 3" with every turn (<!-- m --><a class="postlink" href="http://www.nmra.org/standards/sandrp/s-7.html">http://www.nmra.org/standards/sandrp/s-7.html</a><!-- m -->), but that's from the railhead. So call it 4" if you make your helix subroadbed out of something like 3/4" ply.

Grade% = rise / run x 100%
4"/150" x 100 = 2.6%
Don't forget that the inside will be effectively steeper, since there is less run.
4"/138" x 100 = 2.9%

Can you live with that grade? Since it is on a curve as well, the length of the trains will be quite restricted. The only way to reduce the grade is to increase the radius, since the 4" clearance is pretty much non-negotiable.

So going up 18" using a 4" climb with every turn requires 4.5 turns.
4.5 x 24 feet per turn = 108 feet of helix track.


Something to think about...! I hope it is helpful. I am going to put some other comments in your layout design thread too.

Andrew

21-3/4" radius for the inner track might work, but the more im thinking about it, the more i think i want to have a little bigger radius then that for the inner. Maybe 24" on the inside, and 28" on the outside. This would allow me to run longer trains down or up on the outside track correct since the radius is wider?


If im reading your calculations correct, your saying that i would have a 2.9% grade right? I could live with that.... lol. 18" between the levels would be better anyways, and if i could get away with going that high without too much more work and headache, then thats what i will do. It should also give me a little more "head" room lol
Josh Mader

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#14
shortliner Wrote:One other comment - the tighter the radius, the more likely the train is to "stringline" and haul the cars off the track sideways, instead of hauling them along the track, which is what you want them to do. This may cause problems with the 60' cars on the steeper/tighter gradient. The only real way to find out is to try it out - but go for the largest radius you can fit in and keep the gradient as flat as possible, at the expense of increasing the number of turns
Found this which may give you an idea about space needed HO scale Helix model train elevation kit 2% *NEW ITEM* Item number: 360171276386

This was what i was thinking about and i think i would like to make the radius a little wider as i mentioned in my post above. I really dont want trains derailing and plunging to the floor LOL

do you have a link to that item you posted?
Josh Mader

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#15
nolatron Wrote:While not the most inexpensive option, Ashlin Trains has a 22" radius helix that will do an 11" rise with 4" between levels. Might be able contact them for a custom size if you need another loop for a little more rise.

<!-- m --><a class="postlink" href="http://www.ashlintrains.com/servlet/the-51/railroad-model-train-ho/Detail">http://www.ashlintrains.com/servlet/the ... -ho/Detail</a><!-- m -->

My N-Scale helix came from these folks.

Just wanted to toss that out there as option as well.

AWESOME thanks for the link Shaun!! I am going to seriously consider this. The price isnt too bad, and i would need probably 2 of them kits for my helix. Ill also get in touch with them about getting a custom helix designed and built for me, that would be pretty sweet, and take alot of work out of the picture on my part lol. Hopefully the price wont be too much either lol. $109 for that helix in that link sounds like a pretty good price to me, and well worth the money in my opinion
Josh Mader

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