Helix

Most modelers tend to shy away from the dreaded helix. I was leary about them as well, and as my layout plan progressed, I realized that I would need not only one, but two! As it turns out, it has not been all that bad. I built both of my helixes using the threaded rod method and I think they turned out pretty well. For those of you contemplating building a helix, take a look at the photos and captions below. I will try to explain my helix construction as well as things that went well, and things that did not.

This is the larger of my two helixes. It is a single track 32" radius helix with seven and three quarter turns. This helix brings trains up from my staging yard to the first or second level and vice-versa. Trains can also traverse from the first to second level for a continuous loop if desired. Both main levels also have balloon tracks, or tracks that make a loop around the helix. This allows me to run a train on each level for open houses. They will also be used as staging tracks during operating sessions. Click on this picture as well as others for more information on the construction methods.

This is a photo of the inside of the large helix. Each turn rises approximately four and a half inches, which means the helix portion iteslf rises over three feet. The framework that the helix rests on is made with 2 by 4 lumber and is quite sturdy. I access the inside by the small hole on the left side of the picture, definitely a "crawl space" sort of opening.

This is the smaller of the two helixes. It is just under four turns and takes trains from the first level to the second and vice versa. Like the larger helix, it has balloon tracks around it to allow continuous runs on both levels. These will also be used for staging during operating sessions. Since this helix does not have to service the staging yard, it is much higher than the other one. This makes accessing the inside of this helix much easier. This helix is mounted on a 2 by 4 frame supported by 2 by 2 legs.

Looking down in the inside of the smaller helix, you get a good look at the upper and lower balloon tracks. Both of my helixes are made with one-half inch plywood laminated with one-half inch homasote.

This is where the layout meets the larger helix. You get a good look at the upper level balloon track. Not all the track had been laid when this photo was taken. In the lower left of the photo you can see where the connection is made between the fourth helix turn and the first main level.

This is the connection between the smaller helix and the upper level. Again, you get a pretty good look at the rising helix meeting the balloon track and the benchwork for the upper level.

Here is the framework for the smaller helix. There are twelve 1/4 inch threaded rods that support the entire helix. As luck would have it, the 32 inch radius for my helix was perfect, as it allowed a very simple, time saving method of construction. It also resulted in better, more forgiving clearances. This will be discussed in the next photo.

This is a crude drawing of the pieces that went into the helix turns. I could cut several from a sheet of plywood, and there was very little waste. It took four pieces to make a single turn, which really simplified the construction. Click on the drawing for a much more detailed explanation of what was done and how it all fell into place.

Here is a photo of several assembled helix turns awaiting installation. I would splice the four pieces together with wood glue and a small piece of plywood. I would then laminate on the homasote between the splices. This gave a finished roadbed that was easy to spike into. When I had all of the turns completed, I would align them in a stack like the one in the photo and drill the holes for the threaded rods through them all at once. This really helped in aligning them later. The helix turn on top of the stack is the lowest level turn for the smaller helix. The blocks of wood and metal pieces are for supporting the balloon track. More on those later.

This photo shows two of the eight threaded rods that mount on the inside of the track. These are actually going through the area of plywood that would have been sawed off and wasted if I had cut them out the way I had first planned. These rods are well in from the track, which greatly increases the clearances for the trains traversing the helix. Since there are four pieces of plywood that go into each turn, these rods lined up nice and square when it came time to put everything together. There are also four rods that are mounted outside of the track that are not shown in this photo.

Here is a photo of one of the four rods that are on the outside of the track. These four rods also line up with the splices, of which there are four per turn. For the splice, I simply cut and glued a piece of plywood the same thickness as the homasote roadbed, which can also be seen. The turns are secured above and below with a washer and nut. I also used a lock washer on the top, though I probably did not need to. Do not use a lock washer on the bottom, as it causes a lot of problems while determining your percent of grade as you build the helix.

This is a close up photo of the rod, washer, and nut assembly on one of the inside rods.

I built my helixes because I wanted a double level point to point layout for operation with no duckunders. To do this required two helixes. I also knew that I wanted the ability to run trains in a continuous loop, and if possible, run a train on each level for open houses. To accomplish this, I installed balloon tracks on both levels of both helixes. I call them ballon tracks because they resemble a balloon when looked at from above. Essentially, all a ballon track is is a return loop that runs outside the helix. My first balloon track was the lower level track on the large helix, I'm not even going to show you that one because it is such a mess, though you can see it in some of the photos. The rest of the balloon tracks were built using the method shown here. A mending brace is screwed to the main turn and supports the balloon track.

Since the mending brace is attached to the helix loop, it is on a grade. I wanted my return loops level. Therefore, I had to adjust the height of the return loop using blocks of wood. On the top level, which is shown in this photo, as well as the previous one, the helix track went from being the correct height to being four and a half inches too low as the turn went around and down. To compensate for this, I added blocks to the mending braces below the ballon track subroadbed. This photo shows a riser that is about 2 inches tall. The previous photo shows a riser that is only about one half inch tall.

The problem was just the opposite on the lower level balloon track. Since the first helix turn was rising, the balloon track needed to be lower than the helix turn. To acomplish this, I glued blocks (anti-risers?) to the helix turn, and then screwed the mending braces to them. As you go around the turn, the blocks get bigger, essentially lowering the balloon track in relation to the helix turn so that it stays level and even with the lower level benchwork. This photo shows a five eighth inch anti-riser glued to the helix turn. The balloon track is in the background, and as you can see, is lower than the helix turn.

This photo shows an anti-riser that is about two and a half inches. The lowered balloon track is on the left, the rising helix turn that the anti-riser is glued to is on the right.

My wiring is pretty simple, wires sottered to the rails and the wires run down the outside of the helix and held in place with staples. Be very careful with planning your wiring, as my layout progressed, I had several "bugs" to work out to get the DCC system set up just right.

The finished product. Here is the larger of the two helixes ready to be connected to the rest of the layout. Notice the difference between the clean lines of the upper ballon track conctruction versus the lower. I felt that the way I did the lower one would be stronger, but the resulting appearance makes me think it just wasn't worth it. If I were to do it again, I would have made this one as I did the others.