This page will hopefully help you to understand the construction of my helix. Its not a master class in woodwork or a mathematics wonder sum, its just me with a few bits of wood and a bit of track. I wanted to incorperate a helix into the layout from the original scribblings on bits of paper. So i sat down and thought of the simplest way i could do it.  So off to the model shop i went and bought 4 complete circles of track, 2 3rd raduis and 2 2nd radius. Then onto B&Q and bought a sheet of 8ft by 4ft mdf , which they cut in half to make 2 4ft sqaure boards. I then layed one of the boards on the garden table with 2 complete circles of track on them .  I then marked on the board where the circles were and added a inch each side for train over hang.  Next i thought about the supports, to hold it all up so i added with the pen, notches in the side to hold my spacers. The picture below, shows roughly how it looked on the sheet of wood. I have no sizes, its all by your own judgement.

Next i cut the whole thing out of the MDF (12mm by the way) and cut along the dotted line(above) to make like a coiled spring. Then popped it on supports to test for clearances. Below in the picture you can see , one whole circle(the lower bit) and one half circle i added so i could run trains on it when testing gradients. Below is basically all i used on camelot to go up 7 inches , with a ramp from the top , still going up to joint the rest of the layout where the new junction is now.

Below, you can see the helix taking shape, with the long red line over the top showing roughly where the wooden "box" that covers the helix is now located, that area being about 4ft wide.The box itself is not only to hide the helix , but also acts as a support for the whole thing. The other red lines with the circles  show where the supports are located below the wood, making sure there is clearance on both sides for your longest coaches. At the time this gner white rose was my longest ,and underneath, some old american stock, was my tallest. The space blocks between the decks are all 3 inches high, cut from a single piece of 3x1 inch batten.

Below you can see the helix in place , with the 7 inch height marked on the left and what should be 3 inch not 4 on the right. Looking at it like this, it doesn't look a steep as it does looking down from above. You can also see in this picture the gradient up from the top of the helix(on the right) to the baseboard join on the left . None of my trains have any trouble climbing this gradient with a good length of wagons or coaches. You can also see the beginnings of the box which surrounds it, just sheets of wood at this point.

Here is another view with the box taking shape around the helix and a light installed inside.

Im not really sure what else to right about the whole thing, as it was mainly built as trial and error. With the end result working quiet well, as youve seen in my videos and pictures. Here is another picture showing the join between the 2 circles. Hope these pictures help, as it took me hours to find these on old photo discs. The top level on this picture was the old return loop.

Just another old photo, showing the early stages of Camelot with the helix up the end and the return loop in place.

Well, here it is in its current form, still going strong after 4 years now.