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Thread: Building a Helix with PVC Pipe

  1. #1
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    Default Building a Helix with PVC Pipe

    I have seen a few discussions of utilizing PVC pipe for sub-roadbed, and this particular one is one of the better ones,...
    http://cs.trains.com/mrr/f/88/t/137192.aspx?page=1

    photos at that site

    Then he made a few modifications....
    I will continue thinking outside the box with...

    PIPE ROADBED VERSION 2
    This is version 2 of the pipe roadbed method.

    I used masking tape on the underside of the pipes. Then I added cement between the pipes!!! You don't need to cut all these masonite pieces anymore. Just glue cork roadbed on top of the cement. The cement will not move at all because the round shape of the pipes will no allow it. My cement was not fresh so I got lumps in it. I will try to even out the surface by adding a thin layer of spackle. I think that will be very easy to do because you use the top of the pipes as a support when you even out the spackle. I can asure you that this roadbed will not move in any direction. It must be the strongest roadbed ever... The only thing I need to do is to change the distance between the pipes. It must be a little more when you use cement between the pipes. But I used the same distance in this experiment. Maybe it's possible to join the pipes with smaller pipes instead of wood dowels. Then you can still use the pipes for track power. One cable in each pipe, no visible cables.
    photos
    So now I'm wondering if portions of this idea are a possibility for constructing a 30" helix structure?.
    Last edited by beiland; 06-14-2017 at 03:45 PM. Reason: 30", not 30'

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    Default

    Quote Originally Posted by beiland View Post
    I have seen a few discussions of utilizing PVC pipe for sub-roadbed, and this particular one is one of the better ones,...
    electrolove, Fergie, loathar, tstage, and even Lillen now there are some names that bring back some memories. .... I have electrolove's real e-mail somewhere. If it can find it I'll write and find out how that all ended up. I don't remember what his minimum radius was. I know the original layout was destroyed (in a flood I believe), and don't know if this is the original or a new one.

    Just FYI electrolove's layout is one that morphed from a simple idea into an impressive representation of D&RGW through the Colorado mountains. I don't remember if any of his original wants and requirements were left at the end (other than running the California Zephyr train). Each time we did a revision of the plan he liked it better than the first ideas and replaced them with new wants and requirements. Others would comment and we would revise again. As I said the end result was impressive. It makes a good case study on designing a model railroad. If that site wasn't copyrighted to them I would collect all those posts and make it into a book or at least a "how to" article.
    Last edited by Iron Horseman; 06-14-2017 at 11:12 AM.

  3. #3
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    Default

    You are saying that all of those fellows experimented with this PVC idea?

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    Default Frame Structure for External Helix

    A thought occurred to me this morning....

    How about a outer hexagonal box frame structure (fabricated out of say 1" or 1.5" square-section alum tubes) into which you would place the coiled up PVC pipe. This frame structure would hold the coiled pipe from expanding outwardly further. And vertical square tubes joining the top and bottom 'hexagons' could be the side supports/attachments for the pvc pipe roadbed at the various levels as it rose in grade.

    I'm thinking double pvc tubes for the roadbed as reference above, glued together side by side, with the track laid over the two tubes.

    Sure would make a nice open space access to the helix tracks from inside the circular space of the helix structure, since most of the helix support structure is located on the outboard side of the tracks.

    ??

    PS: The frame structure could be fabricated from wood of course, but I chose alum tubes for 2 reasons:
    1) I have some already that I salvaged from an old screened in porch structure here in FL
    2) I'm looking for materials that are less affected by moisture, humidity, etc ie, alum & pvc

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    Default

    I am pretty mechanically inclined and I really can't grasp what you are describing as made from aluminum square tubing. Do you know how and do you have access to a Heliarc welder for welding up the frame? Being as open as you describe, what's to stop a whole train, loco; or, a few RR cars from falling to the floor in a derailment? I think building a helix from Masonite and/or wood would be far easier to perform. However, if you think your idea has merit, just go for it!
    Last edited by NP2626; 06-15-2017 at 08:23 AM.
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    Quote Originally Posted by beiland View Post
    You are saying that all of those fellows experimented with this PVC idea?
    No, those are just the old friends and regulars of that board who happen to have contributed to that thread. As far as I know Benny is the only one who actually used the pvc. I did find his e-mail and sent him a note to ask how it came out in the long run.

  7. #7
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    Default

    Would be interesting to see how, or if this worked out. As only straight sections seemed to have been shown in those forum posts, I wonder how it actually worked on curves, especially on the sort of radii used on layouts. I've got quite a bit of PVC electrical conduit of 1" or less diameter and even that doesn't curve that well without heating. Once you do that the smoothness of the curve becomes problematical. In a helix, you not only have the radius of the curve to contend with, but the twisting of the roadbed as it rises/falls, basically a continuous screwthread shape.
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  8. #8
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    Quote Originally Posted by Iron Horseman View Post
    electrolove, Fergie, loathar, tstage, and even Lillen now there are some names that bring back some memories. .... I have electrolove's real e-mail somewhere. If it can find it I'll write and find out how that all ended up. I don't remember what his minimum radius was.
    It would be interesting to get him involved with this discussion, since he seems to have experimented a lot with some PVC roadbed methods.
    It would also be interesting to get some of his photos, and/or permission to use some of his photos of his experiments.
    Last edited by beiland; 06-15-2017 at 08:39 PM.

  9. #9
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    Quote Originally Posted by NP2626 View Post
    I am pretty mechanically inclined and I really can't grasp what you are describing as made from aluminum square tubing. Do you know how and do you have access to a Heliarc welder for welding up the frame?
    I'll give you a little sketch before to long as I work out a few more initial thoughts.

    I hope not to have to using welding technics, but rather good old pop-rivet/adhesive joining of the square-tube aluminum extrusions.

    Being as open as you describe, what's to stop a whole train, loco; or, a few RR cars from falling to the floor in a derailment?
    Haven't worked out those details yet, ...but on many existing helix structures, particularly this built with all-thread rods, what keeps them from letting the trains fall into the opening in the center of the helix? ...just a few all-thread rods?
    Last edited by beiland; 06-15-2017 at 09:29 PM.

  10. #10
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    Default General Concept

    Just to help with visualizing the concept. Lets say you had a 5 foot square by 2 foot deep wooden box that had no top on it.

    Now lets coil some 1/2 inch dia PVC pipe into that box without overlapping the pipe upon itself,...the coil will grow in height within the box as we coil an ever-longer piece of PVC tube into that box. The box will force the normally straight tube into a nice 5 foot, (60" diameter circle,...30" radius) within the box. (btw, I have a few sources already that confirm that this PVC tubing could be coiled into as little as 24" radius).

    Now lets say we want to keep those coils of PVC tubing from actually lying directly against the wooden inside surface of the box. I think we need to use a few of these spaced evenly around the perimeter of the tubes,....PVC snap saddles
    Name:  PVC white saddle.jpg
Views: 332
Size:  7.6 KB
    But wait, look at this one, its threaded
    Name:  sch-40-saddle_1.jpg
Views: 322
Size:  10.5 KB
    We could use this saddle to hold the coiled tube, and bolt the saddle to the side of the wooden box.

    Now what if our single PVC tube coil was instead a double tube (two tubes glued together). Its been done before, as a form of spline roadbed.
    Last edited by beiland; 06-15-2017 at 09:31 PM.

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