# Migraine from trying to design a Helix



## sawgunner (Mar 3, 2012)

After reading some threads here and searching the internet i found this page http://www.linsjunction.com/images/helix_clinic.pdf about designing and building a helix but and having lots of trouble with the math from it. I am good at "basic carpentry" but this feels out side my realm or maybe i'm suffering from what i normally do which is to over think things to death.

would like it to start from my table height of 41" and go up 18" to the next level at 59" @ a 3% grade and 28" radius for the helix.

can someone explain the steps to do this in plain english and or mathematical terms that i can understand or draw out some sketches i can print off to help aid in this process.

thanks a bunch


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## swiggy (Jan 25, 2010)

you may want to save the headaches.......wait, sorry, migraines are a different breed altogether. check this out...maybe email them for an order? May give you some ideas as well

http://www.ashlintrains.com/servlet/the-51/railroad-model-train-ho/Detail


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## gunrunnerjohn (Nov 10, 2010)

Each turn of the Helix would rise 5.28 inches using a 28" radius, so it would be about 3.5 turns to make the 18" rise.


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## sawgunner (Mar 3, 2012)

cool! 

now what is the best thickness plywood to use for this that won't warp or twist over time but still leave me enough between the loops to clear roadbed, track and double stacks?


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## gunrunnerjohn (Nov 10, 2010)

Well, since you have 5.25" for each turn, it seems you can use whatever you need, surely you don't need more than about 3.5" clearance for HO stuff, right? Let's say 4" for double-stack containers, right? The spacing between the decks should be plenty to allow whatever construction you like for the decking.


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## sawgunner (Mar 3, 2012)

Thanks John!

I'll start to build it this weekend and take some pics of the progress


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## joed2323 (Oct 17, 2010)

Look at sstlaure aka scotts build thread http://www.modeltrainforum.com/showthread.php?t=8241&highlight=helix

or this one where me and him talk about the actual building of a http://www.modeltrainforum.com/showthread.php?t=10783&highlight=helix
scotts 

Start at page 18 of my thread, scott goes in detail on how he built up his helix and basically explains where to start.

I have my basic bench work started, and as soon as i get something worth not laughing over :laugh: i will post more of my progress

Scott should catch this thread shortly, and he will be giving his input


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## gunrunnerjohn (Nov 10, 2010)

The formulas are pretty simple, a 1% grade is 1" in 100 inches, so a 3% grade is 3" in 100". Given you have a 28" radius, that's a 56" diameter circle. Multiply that time PII (3.1416) and you get 175.9296. Multiply that times the grade you want, 3%, and you get 5.277888" for each trip around.

One thing of note, you will experience a bit more load going on curves, so if you're working close to the limit, you may want to consider doing maybe 2.5% for the grade to take the curves into account. That would give you 4.3" for each trip around, so it would be a bit tighter in overhead space.

Something to consider...


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## sawgunner (Mar 3, 2012)

ok here is the basic 1st level track plan i am going with


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## joed2323 (Oct 17, 2010)

Awesome sawgunner! cant wait to see somebody else tackling a helix or two


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## sawgunner (Mar 3, 2012)

there will be 2 in mine both will be single track and function as both up and down for the second level. one for east bound and one for west bound


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## sstlaure (Oct 12, 2010)

Why so steep on the helix grade? That grade plus a constant curve could limit things. With a 28" radius, you really don't need to climb any more than 4" per revolution, you'd end up with 4.5 revolutions to climb your desired 18" and you'd have a 2.2% grade. (176" run/4" climb)

I personally like this 4" climb per revolution because you can use 1x4 dimensional lumber on it's side (3.5" thickness) to set the grade and the spacing between layers of the helix. That plus 1/2" plyboard gets you the 4"/revolution. It's just right for doublestacks and autorack height cars with another 1/2" or so clearance to spare between the top of the cars and the bottom of the plyboard.


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## cv_acr (Oct 28, 2011)

3% grade on the helix is not a great idea - that will severely limit train lengths, and light cars could be in danger of "string line" derailments where they pull to the centre of the curve.

The minimum rail to bottom clearance in HO scale is 3.5" (if you don't use modern full size cars you can get away with a little less, but not really recommended. So rail to rail height separation will be about 4". There's not really any reason to go higher that that. 

Having set the separation height, the radius of the helix really sets the grade. 

The length of track in each turn of the helix will be approximately 2 x pi x radius (formula for the circumference of a circle). 

So the grade of a helix with 4" level separation (3.5" spacers and 1/2" plywood base) will work out to 4 / (2 x 3.1416 x radius) x 100%, or about 0.637 / radius for the grade.
By increasing the radius, you decrease the grade and vice versa.

27" radius would make a grade of about 2.4%
28" radius would make a grade of about 2.3%
29" radius would make a grade of about 2.2%
et cetera.


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## sawgunner (Mar 3, 2012)

i do plan on pulling 100 car trains up and down these with 3 locos on front and 1 or 2 on back. 3% didn't seem so bad on my last rendition of this thing when i was only going up to 4.5" to add a upper main to the original layout but i can see the point with it being only one turn as opposed to 3.5 where trouble can arrise.

I'll do it at 2.3% and see how it turns out. The upper level is pretty much just going to be staging for the full trains and some tracks for the local to come pick up strings to go switch.

looking at doing 2 grain trains, 2 intermodals, and 2 coal drags as primaries for through freights maybe a couple mixed as well. depends on how much room for tracks i end up with on the upper level.


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## gunrunnerjohn (Nov 10, 2010)

Measure your tallest car or locomotive, that's how much clearance you need.


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## cv_acr (Oct 28, 2011)

sawgunner said:


> i do plan on pulling 100 car trains up and down these with 3 locos on front and 1 or 2 on back. 3% didn't seem so bad on my last rendition of this thing when i was only going up to 4.5" to add a upper main to the original layout but i can see the point with it being only one turn as opposed to 3.5 where trouble can arrise.


take this as the voice of experience: that is not likely to happen. Especially not at the original 3% idea.

At my club we have a number of helices, all with the 4" rail to rail separation. Most are minimum 30" radius. We routinely run 40+ trains through here with little issues, although a big train NEEDS at least three, often 4 engines to make it smoothly. We have done over 50, but we try to limit things to around 40 (the 50 car train didn't derail, but it did stall out). That is a really big train on any model railway layout anyway.

Note I said those helices are 30"R. We have one that is down to a 28" on our branchline, and while we have put a 40 car train up it successfully, the tighter helix puts an incredible strain on the first few cars in the train. If the cars near the front are even slightly off spec, they can derail. We try to limit any train going up the branchline to a max of 35 cars. This is enough to be mostly consistently reliable. 40 cars up this helix is a bit of a gamble.

Not only does the tighter radius increase the actual grade (the smaller circle means less distance to make the rise) a curved grade is harder to get up than a straight grade. So the tighter the helix, the more the actual grade, but also the more the effect of the curve. The theory promoted by Model Railroad Hobbyist magazine is that a sharp curve can add up to half a percent to the "effective" grade; which is pretty significant when we're shooting for a 2-2.5% actual target.

Spacing out helpers does help take some of the strain off by spreading out the forces and reducing the amount the lead engines are pushing (that's the same reason real railroads use helpers/distributed power) as long as the helper engines don't stall or run slower than the lead engines. You need the slack to stay pushed in. As soon as something causes the train to stretch, you're done for.

The key with helices is to keep the grade as low as you can afford to without making the helix radius so large it takes up all your space, and use as many turns as it takes to attain the correct height. Size vs. steepness is always the trade off.

If you want to run big trains, all of your equipment has to be very reliable. This means not just good running condition, but SIMILAR and consistent running conditions and car weights. Our club standards for every car include NMRA recommended weight, free-rolling metal (no plastic) wheelsets (car must roll away on its own if placed on a 1% grade. If it won't roll downhill, it fails) and Kadee couplers (a good metal clone like the new Walthers ProtoMax is acceptable, but the metal clones offered by Rapido and TrueLine Trains have experience some spotty QC and reliability issues, and any sort of plastic coupler is not acceptable). Trust me, if you want to go big, you will not be sorry to adhere to very strict car standards. Detail and accuracy issues are up to your personal feelings, but when it comes to MECHANICAL standards, don't accept anything not up to snuff. If it fails a test, pull it until it can be repaired.

If you want to see photos and video from the club layout, check out:
http://www.wrmrc.ca
http://www.youtube.com/wrmrc
It's a large layout under heavy construction.


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## sawgunner (Mar 3, 2012)

I understand what your saying in terms of weight and strain. if i had my way i'd have a full basement to work with and not less than a 1/4 of one. I'm also am still thinking that what i want to do is feasible given proper weight distribution, and power placement.

I don't follow NMRA standard in regards to car weight as to me it is very unrealistic that every car on a railroad will weigh the exact same. obviously i will put lighter cars towards the back as i have always done. all of my cars are either walthers gold line, atlas masters, Intermountain, or athearn so they all have metal wheels and KD's on them. 

Motive power will be a mix of Atlas, Athearn RTR/Genesis, Intermountain latest style diesels down to one ABA set of F units pulling the Southern Belle

Keep in mind I am certainly not the brightest crayon in the box but there are tricks to doing anything other than following certain standards (to which some do not really make any sense)


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## santafealltheway (Nov 27, 2012)

I was playing around with a helix, i found if you make it just high enough that all your cars clear the track above, it works great. Takes all the math out of it.


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## T-Man (May 16, 2008)

The bigger the circle the easier it is.


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## sawgunner (Mar 3, 2012)

well Thanks to John i've got the math part figured out and like i said i guess i was way over thinking it.

as for the diameter i am currently working on what the max size i can go without disrupting what i would like to do on the lower level.

now if i could get clearance to tunnel through the wall and go into the laundry room and put the helix there that would be great but not thinking that's going to happen so back to the original


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## gunrunnerjohn (Nov 10, 2010)

Maybe the helix could be over the washing machine.


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## sawgunner (Mar 3, 2012)

LOL with the size of that room i could almost triple the size of my layout if i could tunnel through the wall!!

will have to go get a pic


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## sawgunner (Mar 3, 2012)

here is the other option if i don't do a helix. The bluish gray track goes up from 0 - 18"


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## joed2323 (Oct 17, 2010)

i would do a helix just because they look cool and macho


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## 05Slowbalt (Dec 19, 2011)

Sawgunner I am starting on my two Helix this coming weekend as I will have 5 days off. I will post start to finish. I don't know everything but I have learned alot and we will see how it goes lol.


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## manchesterjim (Dec 30, 2011)

gunrunnerjohn said:


> Maybe the helix could be over the washing machine.


CAREFUL!!!!.....next thing you know....your beautiful helix becomes:










:laugh: Just sayin.......

Jim


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## NIMT (Jan 6, 2011)

manchesterjim said:


> CAREFUL!!!!.....next thing you know....your beautiful helix becomes:
> 
> 
> 
> ...


I will second that!


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## sstlaure (Oct 12, 2010)

sawgunner said:


> LOL with the size of that room i could almost triple the size of my layout if i could tunnel through the wall!!
> 
> will have to go get a pic


Go through the wall....they are surprisingly easy to modify.


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