Building a helix

frank martin Jul 20, 2000

  1. frank martin

    frank martin E-Mail Bounces

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    Has anyone built a helix? What are some sugestions on building one. How much trouble have you had with derailments. I want to buildone with 36 inch radius and 4 tracks.
     
  2. atsfman

    atsfman TrainBoard Member

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    I have a single track helix that has been in place since 1989 and have not had problems with it. It is in HO, 36" radius, I used Atlas code 100, secured to homabed roadbed on 5/8"plywood. The only derailments have been mechanical failures on rolling stock. Which brings up an important point, make sure you have access to it for rerailing, because nothing works 100 percent forever. My derailments have been minimal however. It makes two and half revolutions, connecting the top deck of the railroad with the middle deck and is hidden from view by a major freight yard located over the top of it. However, I can crawl under benchwork and come up in the middle of it. Two more things, I use DCC, make sure you have a plug near the helix so you can connect a throttle for testing, make sure you have some sort of lighting that can be turned on when doing maintenance. Hope this has been of help.

    Bob Miller
     
  3. ChrisDante

    ChrisDante TrainBoard Member

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    I am building a 2 track helix that will raise the track 17inches. The rest of my layout has code 70 rail, however the helix will have code 100. We are limiting the grade to 2%. The inner track will be 27" radius and the outer 30". I ran across an interesting concept that we are incorporating into our design. We will be using 16 threaded steel rods, 3/8" diameter and 48" long, as the vertical supports. They will locate the virtical rise of the treads of the helix by nuts and washers giving us total adjustment of grade. The rods will be secured at the bottom into plates placed around a hollow octogon at 8 points around the circle. The treads are 1/2" by 6" plywood with cork laid as roadbed.
    Follow the advice of Mr. Miller as well, ie keep it hollow and light it.
    Our helix will be hidden in a mountain.
    I am getting a digital camera in a couple of months and will post pictures as available.
    Measure twice then cut and good luck, keep us posted.


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    When in doubt, empty your magazine.
     
  4. Robin Matthysen

    Robin Matthysen Passed Away October 17, 2005 In Memoriam

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    The M.A.T. has a single track helix that then leads to spiral tunnels. I hoped to use 20inch diameter but had to settle for 15 inches diameter because of space restrictions. This isn't too bad for N scale. As mentioned by others, easy access is essential. I get to mine from underneath. For light I use an automotive trouble light and have a couple of hooks in place for it. I also have access in other mountain areas so a mobile light is handy. I didn't want to install permanent lights in these areas as I do not have to go in there that often. Code 100 track on half inch plywood and 1/8th inch cork roadbed. Good track work saves many problems later so take the time to do it right. The temptation is to get it in operation quickly but patience wins out in the long run.

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    Robin
    Maberly and Tayside
     
  5. ncng

    ncng TrainBoard Member

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    ChrisDante: I would like to know how much clearance you are allowing and what your roadbed thickness is. A 27" radius at 2% grade only provides 3.39" of climb and doesn't allow for any transitions at the start of the climb or at the termination of the climb.

    I have a double track helix that has a minimum radius of 36" and a maximum grade of 2.25%. I use 1/2" plywood with 1/2" homasote. I allow a minimum of 3.75" of clearance.
     
  6. ChrisDante

    ChrisDante TrainBoard Member

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    Reply to ncng:

    I should have made it clearer, the actual diameter of the roadbed is 62.5" and the easments were not included in my post, as they are outside the actual helix. I am using 1/2" plywood and cork roadbed with a 3.5 in clearence. If I end up with 2.5% that'll be ok. Since we're using the rods we can adjust. There will be no outsized cars on the helix, in fact mostly passenger.

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    When in doubt, empty your magazine.
     
  7. mtaylor

    mtaylor Staff Member TrainBoard Supporter

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    I am building a N-Scale monster layout with mutiple levels. My latest rough draft plan does not use any helixs at all but uses a mostly gradual grade and heavy grades in other areas. The reason for this plan?....I am scared stiff trying to figure out how to build a helix. How do you ensure consistant grade? It's easy for me to specify a 2% grade but how move that from paper to real life? Also, what is the formula for figuring out grades. I am still considering the use of two Helixes (how does on spell that?) between levels 1 and two and between two and three. There is also plans for level 0 which is for staging. Currently access to this level is planned to use a medium grade.

    I am Helix dumb so any help would be great. I bought the MR benchwork book to see if that would help.....a little.

    Thanks
    Matt
     
  8. ChrisDante

    ChrisDante TrainBoard Member

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    Mat,
    Here's some help with grades and with the helix(s). To determine a grade, here's two of many. First a 2% grade is 2 units in 100 units [units= feet, inches, yards, miles, etc.]

    Our most used method is to buy a grade device at a RR hobbie shop. A bunch of companies make them, I think you can find one in Walthers. Its a plastic device that hooks on to the end of a 2 or 4 ft level. Lay it on the tracks and raise the grauated end until the bubble is centered and read the grade.

    The second is to take a flat car and carefully glue a ruler vertically on the car. Make sure it is perfectly vertical. Next take a carpenter's transit and sight to a point on the ruler. Run the flat car to your next point, a known distance, and and read it again. Do the math and you've got your grade.

    To make the helix adjustable, here's what we're doing. Construct a rigid frame, about the same as your roadbed outer diameter. Build an octagonal on top of the frame.[we're using 1/2X4 lumber]. At the corners of each leg of the octagonal screw on a plate 90deg. to the octagon facing the center of the helix.[these will be the anchors of our vertical rods]. Place two threaded rods [we'er using 3/8ths steel]vertically on each plate, making sure they are inside and outside the diameter of your track clearence. You should use a total of 16 steel rods, in 8 pairs.
    Cut your subroadbed[we're using c/c 1/2"plywood]in sections, drill holes to match the steel rods. Place a nut and washer inbetween each subroadbed section on the rods. Sister the roadbed sections together. Now all you have to do is raise the completed helix from the bottom, layer by layer with the nuts and washers untill you get to your desired grade[we're raising the helix to a rough grade then fine tuning it using the nuts to move each section up and down as necessary]. Now you have an adjustable helix.

    Our's is under construction now, and I will update you as to our mistakes when they occur. I don't have a digital camera, but if I can borrow one I'll take some "in progress" pictures.

    Best of Luck

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    When in doubt, empty your magazine.

    [This message has been edited by ChrisDante (edited 25 July 2000).]
     

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