Model Railroading > Helix Help

I am hoping on building a helix however I have never done that before, anyone here have some tips? I would be really interested if anyone knows a website that can help me design one. I have no idea about Radius; I’m going with 30" inside track and 36" outside track. Can I go smaller?
Thanks

Look at Bruce Freidman's listing a few down where he is talking about the laser level. He has some photo's which should give you good insight. Also, look at Blair's (jackpot)Blog "northofNarrobri.com". He has some good photos and narrative. Beware though as Blair's is a helix on an Australian layout so it goes the other way around when you send it down. ;~)

My advice is get good tools as you will never get the precision you require cutting wood manually. I recommend having access to a quality drop saw to cut all risers uniform and square. If one has access to a CNC cutter it is ideal for cutting the plywood into circles, however, good quality jigsaw will work too. Do not use cheap plywood and do not scrimp on the thickness. Personally, I would go with 17mm thick ply but people always tell me I "over engineer" (I consider that a compliment).

Also, when it comes to trying to save money, you can do it by making the helix tight (less track). This will also save space, however, my warning is do not do it. Try to go for a minimum of 30" radius but I would design my layout with a larger 36" radius as a minimum. Blair's Narrobri layout will be running shorter trains and no passenger cars whereas you might not so his is tighter it looks like.

There is an excellent commercial product out there that will have your helix up and running in a weekend. Once you read Blair's escapade, you may consider this expensive option cheaper as he said he got his right on the 3rd effort. Take a look at Easy Helix: http://www.easyhelix.com/ This has the advantage of being something you can salvage should you ever move and cannot keep your layout.

I also recommend Tony Koester's book on Double Deck layouts as a good resource.

Rick



Edited 2 time(s). Last edit at 10/25/09 06:45 by rschonfelder.

An observation on the helix ----
I notice that most modelers build their helix double track with an up side and a down side. Why not build a single track helix with tunnel portals and ventilation structures at both ends. Think about the famous RR tunnels, Moffat, the Cascade crossings etc. How many of them are double track? This would give you the ability to "lose" an entire train in the tunnel (instead of having it stick out both ends). It would also introduce an operational element into your running as trains would have to wait for other trains to clear the tunnel and for the tunnel to ventilate. The problem is that it would not allow for continuous running of two trains in opposite directions if that was one of your goals.

Old Bob out in Lost Wages

I built this one out of 3/16 luan plywood and 1X4 blocks for risers in 2004. It`s 84 inches in diameter and rises only 59/16 inches in one turn. That`s plenty of clearance for the highest of doublestack cars. My track centers are 2 3/8 inches. Build a perfect foundation for the 1st turn and the rest falls into place using 1X4 blocks for risers. A standard 1X4 is 3 1/2 inches wide (56/16 inches) plus the 3/16 thick plywood makes for the 59/16 rise. When suported like this the plywood is MORE than strong enough. The luan is also moisture resistance and doesn`t cost an arm and a leg. Be careful when you work with this stuff. The splinters are like swords. Wear gloves and sand all the edges good. I used a 4 ft. Golfsmith metal ruler with holes drilled in it to swing the radius.

twl

ontrail Wrote:
-------------------------------------------------------
> I am hoping on building a helix however I have
> never done that before, anyone here have some
> tips? I would be really interested if anyone knows
> a website that can help me design one. I have no
> idea about Radius; I’m going with 30" inside
> track and 36" outside track. Can I go smaller?
> Thanks



Edited 3 time(s). Last edit at 10/25/09 08:50 by keysubdiv.

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Whatever you do, the correct line of thinking is that if you've got to skimp or worry
about cutting down on the radius or raising the grade don't bother building it. You'll
spend your whole life fishing out derailments.

The wood spacer method looks like the way to go, takes a little more up-front work but it looks more consistent. Another method uses threaded rods with appropriate hardware, which is said to allow more adjustment, seems to lead to problems.

Beware of installing the plywood segments while flat and then lifting them into final location. The method adds some sort of an additional twist to the plywood.
Another curiosity is that the finished helix has a dis-proportional presence in the room. I refer to it as the 800 pound gorilla in the train room. Didn't think it was going to be that large, it's truly 3-dimensional compared to most of the Layout which is closer to two dimensional.

Thanks guys..
So what kind of a grade am I looking at? I thinks the plywood idea is where I am heading, however the size looks daunting. Ill have to measure it out and see.

Most of the helixes for HO scale layouts I have built are double track with 30" radius on the inside and 32-1/2 radius on the outside. I have never had any problems with overhang with very long passenger cars. These radii work to about a 2% grade.

I use two layers of 1/4" plywood glued together with 1/4" threaded rods, nuts and washers. I made a template out of cardboard for 8 sections to a circle which includes the track center line. I purchased a very long 1/4" drill bit from Home Depot to drill the holes on the outside for the threaded rod. I use temporary spacer blocks from 2x4 pieces of plywood to get the 3" clearance. The joints on the sandwiched plywood are staggered. This method provides the smallest outside diameter for a given radius. I also use a clearance of 2-1/2" from the center line of the outside track to the outside of the subroadbed with the threaded rod holes drilled about 3/8" from the outside edge.

I also use a small block of wood about 3 inches long with a line level on top of it and a wood screw on the far underside. I build the bottom framework out of 1x2 L girders. I splice my entrance and exiting roadbed to and from the helix much like the sandwiched subroadbed in the helix. I have built several helixes and helped a friend build two. We can say that the helixes have the best track on the layouts.

I use ordinary risers screwed to the underside of the first level subroadbed attached to the L girders. Start at the beginning of the helix with the level and adjust the screw on the grade level so the bubble is level with a slight grade and work your way around that first level until you get the point that it crosses over itself all the time adjusting your risers so that the bubble is level. Also make sure the subroadbed is level horizontally (this is very important.) Now, if the crossover of the first level is too high, back off your screw and start over. Do this until you can go all the way around with the bubble level and the first level crosses over itself a the correct clearance (3" works for me).

Lay your track as you go up. After you have built your first level the rest is easy with gluing your subroadbed together and holding with clamps and laying track. It really is easy and a work of art when you are finished.

ontrail Wrote:
-------------------------------------------------------
> Thanks guys..
> So what kind of a grade am I looking at? I thinks
> the plywood idea is where I am heading, however
> the size looks daunting. Ill have to measure it
> out and see.


With a 36" radius, and a 4" rise you get very roughly Circ =2 Pi R or 76 x Pi or about 240", Rise over Run 240/4 or about a 1.6% grade. Which should be attainable by just about any train without needing helpers, short trains or special attention when downbound. But that is also going to be at least 6.5' across. If you got to a 30" radius and 4" rise you get to over a 2% grade and that is going to start getting into challenges.

Go to my website www.bnsfchillisub.com and look at "Local Layouts", check out Garth's "Kansas City Terminal" layout. This should show you everything you need to build a great helix.

Bruce

My first helix had a radius of 30". I ran 30 cars train up it without any problems. I do agree on not using cheap lumber. I used cheap 3ply 1/2" plywood. Never again. I also used threaded though rod as I was able to tune the helix. The layout came down1 1/2 years ago and all that is left from that helix is the threaded rod which will be used on the next helix.

Wictl

Bruce: Nice website and pictures, but how on earth did you lay the helix track after the helix was constructed? I thought that you had to lay the track simultaneously as you built the helix. Jim Leighty