Helix calcs in XTrkCad

[Tom Bryant_MR]

I'm working on a helix using XTrkCad.

Elevation Diff = 12"
Radius = 24"
Turns = 4
Angular Separation = 225
Grade = 1.721
Vertical Separation = 2.6

Does roadbed, plus track, plus highest car need to fit in this space ?

[SpaceMouse]

Yes, plus the width of the wood. You won'r make it.

[selector]

Your vertical separation is too little. Try 3.5" as a minimum in order to allow 'fixing' derailments, etc. Also, your radius is a too tight, as a result.

[rrinker]

ditto and ditto. The distance shown is the space from the bottom of the track of one level to the bottom of the track of the next turn. You need to also allow for the wood, ballast, and track thickness. For HO you want a minimum of 3.5" railhead to railhead, to allow clearance for cars. PLUS the thickness of the structure and roadbed. PLUS a little more if you want to be able to reach your hand in.

--Randy

[SpaceMouse]

I'm not planning any roadbead in my helix. It will not be a scenicd part of the layout.

[Tom Bryant_MR]

Thanks all [:)]. That clears up a few things. This is my first layout in HO and the size of how things tend to spread out really amazes me. And I'm from Texas. It appears that vertical separation is affected by a couple of factors. One, the pure math of elevation diff / the number of turns and two, as the angular separation increases, the vertical separation decreases. This now makes sense. Even if you specify 3 turns and the output of the helix is less than the full 3 turns, then the elevation has to be spread over not 3 turns but some factor less than 3 turns but still greater than 2 - in this case. So, my numbers now look like:

Elevation Diff = 12"
Radius = 28" (added 4" to keep grade < 2)
Turns = 3
Angular Separation = 180 (will swing entrance 90 degrees so exit comes out where I need)
Grade = 1.949
Vertical Separation = 3.4

I measured one of my 40' box from bottom of rail to top and get 2.4" Assuming, 1/2 inch wood base, that gets me to 2.9" and leaves .5" clearance - a little tight.

I can well understand now why many have said that the helix is a space hog - and hidden trackage at that [V]

I haven't looked into what size plywood base is being used. 1/2" seems a bit on the high side.

[selector]

Half-inch ply is too heavy for your ramps in your helix, if that is what you just said. A quarter inch would be plenty considering its purpose and weight bearing requirements. In fact, you could easily get away with MDF, doorskin, or masonite cut to shape and lengths, assuming your supports are not only at each quarter of the circle (90 deg apart).

BTW, that lone 1/2" in clearance that you will have left is veerrrrryyy tight. Could end up limiting you in what you can run up and down that helix.

[Tom Bryant_MR]

QUOTE: Originally posted by selector

Half-inch ply is too heavy for your ramps in your helix, if that is what you just said. A quarter inch would be plenty considering its purpose and weight bearing requirements. In fact, you could easily get away with MDF, doorskin, or masonite cut to shape and lengths, assuming your supports are not only at each quarter of the circle (90 deg apart).

BTW, that lone 1/2" in clearance that you will have left is veerrrrryyy tight. Could end up limiting you in what you can run up and down that helix.

Good points and agree with all. In order to keep the minimum vertical separation at 3.4" but yet adjust the almost 2% grade down to ~ 1.5% grade, I had to pu***he radius from 28" to 38". Now I was looking at a "tube" taking up 6 ft of my 10 x 12 ft room. I've blown off (deleted) the helix. I'll experiment with a possible around the room solution.

Thanks again for the inputs.

[Anonymous]

Please let me know, about this. I am building one also.