To build a small helix.

[lionelsoni]

It looks like you used half the nominal diameter to the ends of the ties, or 21 inches, for the radius. It is actually more like 20.25 (for O27) to the center of the track, for a grade of 4.31 percent.

However, if you can exclude Superliners and intermodal stuff from the helix, almost everything else can tolerate 5 inches, railhead-to-railhead, assuming O27 track on 1/2-inch plywood. This is a plausible 3.93 percent, especially with a little negative superelevation.

[Boyd]

I just figured a 42" helix with 6.75" spacing railhead to railhead would be a 5.11% grade. I'm working on drawings for the layout using loops instead of the steep grades a 42" helix would need.

[Boyd]

I just did some measuring, a 54" circle would be pushing too much into walking areas. So a 42" is it. With 6.75" of spacing, railhead to railhead its looking close to 6% grade. I would really have to change the room a lot more than I want to, to install a bigger helix. An eliptical or cam lobe circle shaped helix would lessen the grade. I could maybe try an extention into and out of the closet like I mentioned in another thread before,, but it would have to have quick swingup sections for easy access to plumbing that is in past the closet.

[Big_Boy_4005]

Actually guys, Boyd lives near me, and has visited the house and seen the helix. He even has my phone number.

MTH double stacks are going to be the tallest, needing a good 6" head space. They measure 5-3/4" off the rails.

[ChiefEagles]

Big Boy [Elliot] is building a big one and knows the "ins and outs". Maybe he can give you some hints.

[spankybird]

Here is a thread that you should read on helix

http://www.trains.com/community/forum/topic.asp?page=-1&TOPIC_ID=24593&REPLY_ID=240243#240243

I’m afraid that the diameter that you want to build will have to steep of a grade.
tom

[Anonymous]

BOYD
There are two places I have found that could help you build your helix.

The following web site has helixes you can buy, but has pictures that may help in building one.
www.trainstyles.com

In the December 2004 issue of Railroad Model Craftsman, Pages 88 to 90. There is an article on making a octagonal helixes.
Hope these help.

[daan]

Yes, there is difference in traction. There was a huge test in the CTT about the difference between normal, magnetraction and rubber grip tyres.
One thing in advance though, if you want to build a spiral, make it solid and well build. better spend a few bucks more on a good base and solid anchoring, since if it's done cheap and fast a spiral doesn't work out. Rails will bend under load, derailments causing trains to smash from feet-high to the ground and grades shifting angles when a locomotive passes by due to the flexing of unsupported trackwork.
It will only get frustration that way.
You could use 4 or 8 stands made of wood, with a wood spiral screwed onto it. On the wood you could fix the rails, and on the sides you could make a small edge of wood to keep derailed trains onto the spiral.
If the spiral is solid and doesn't flex or wobble, then it will work great, though the angle will limit the trains you run thoroughly. You could do a test with your trains and a small curve supported by blocks to see what the train can haul up the hill.

[Boyd]

Well, I think I'm going for it. Build a small helix, using either 42" or 54" maximum circle size. It will have 3 to 3 1/2 loops. Its low budget for sure. I'm very mechanically inclined. My first idea is to use a threaded metal rod running vertical in the center,, with nuts, washers and plastic or insulated thin metal rods start at the bottom and build it going up like a spiral staircase. The plastic pieces or insulated metal drilled at each end for the threaded rods. I could use threaded rods, nuts and washers on the outside too for easy adjustability. I know the circle size will limit the trains that can climb up/go down this but with a limited bedroom layout I would get bored with trains just going around and around the room. There is an upper shelf on one side of the room where the trains can go to and have a real destination.
Also,, what clearance do I need in order to accomodate the tallest possible train cars in the Hi-rail market.
Is there any difference in traction between any of the types/brands of track in those sizes?