Ho Track Problems...

Discussion in 'HO Scale Model Trains' started by jerry lewis, Apr 5, 2007.

  1. Torpedo

    Torpedo Member

    I presume you used the now banned CCA treated wood (AKA the good stuff). The new stuff is supposed to be highly corrosive to regular fasteners, requiring either best quality hot dipped galvanized or stainless steel fasteners.

    Here is an article on the subject.
  2. cidchase

    cidchase Active Member

    I laid this out in cad just for grins. In a 50" long rail, I put in a kink that bows out 1/8" on both sides over a 6" span. I think this is about a typical type of "s" kink, it's done this on my layout. The track only has to grow (or the base shrink) by .028" (less than 1/32") or .056% to put a kink this big in the track. That's roughly 1/20 of one percent expansion or contraction, it doesn't take much!! :eek: :eek:
    A couple of 0.030" unsoldered gaps affords a lot of protection!:thumb: I have a turnout that had a rail pop out of the plastic spikes on account of this :curse: :cry: . While I'm at it, I think I will replace it with Peco, which is why I was asking about the Peco rail height in the other thread. :)

    Attached Files:

  3. Gary S.

    Gary S. Senior Member

    I put feeders to every piece of flex track, and left small gaps at the rail joiners with no solder. I did this because the layout is in an un-climate-controlled garage. I used 3/4" exterior plywood ripped into 3" wide, 8 foot long strips for the framing, with 1/4" birch plywood glued and screwed to the frame, then 2" extruded foam contact-cemented to the birch plywood. Then cork roadbed glued to the foam, track glued to the cork. All the framework and plywood has two coats of paint. Also, the benchwork was completed and set on the shelfing brackets for almost a year before I started laying track.

    Hopefully I won't have any expansion problems, that would be HORRIBLE :curse: after the amount of work that goes into these layouts. My sincere condolences for those who are experiencing the problems.
  4. pgandw

    pgandw Active Member


    Having lived both East and West (I prefer the West, we're moving to Colorado this summer :thumb:), you stated the difference in our experiences without realizing it. The expansion of wood from moisture content change is far, far greater than any expansion/contraction from temperature change.

    In the East (especially places like New England and the Great Lakes states) winters are dry because a) cold air can't hold much moisture to begin with; b) this dry cold air is heated, drying it even further. In the summer, especially if you have no air conditioning, the wood swells with all the humidity.

    In the West, summers are typically low humidity so the change in mosisture content isn't nearly as great over the course of a year. When away from the water, temperature ranges are much greater with dry air, as you point out. But since wood doesn't react nearly as much to temperature change as it does to moisture changes, you have sufficient stability in Colorado, especially with plywood.

    Our friends in Arizona, especially the ones with garage layouts, do have enough temperature range that rail contraction/expansion due to temperature swings can be an issue.

    The biggest issue in the West is getting lumber products that haven't been dried enough or properly from when they were sawn/manufactured. As the wood/plywood dries unevenly, it warps because the wood fibers shrink unevenly. Hence the twisted pretzels that passes for lumber at Home Depot and Lowe's. But once dried, there should be no further probelms because of the stable moisture content.

    What part of Colorado should I look for you in? We'll be heading to the Colorado Springs area.
  5. LocoIndy76

    LocoIndy76 Member

    Wasn't trying to be argumentative..... However.......
    I'm somewhat confused, in your first post you said plywood isn't affected by humidity, but in this post you're saying that you don't have problems because of LOW humidity.... I'm not sure if it is humidity driven or not... I would probably agree with you that it is more based on actual RAINFALL amounts in my case.. So you are probably DEAD ON on that count.. The lumber I dealt with probably did get wet in some stages of the house being built and absorbed some water and expanded over time... I figured it would mainly be because of humidity, BUT it may be more the actual PRECIPITATION...... :thumb:

    I don't claim to be expert by ANY means.... Just going by experience here.... SInce I don't live or deliver lumber in other "climates" my observations are somewhat biased.

    In my case I SCREWED 2x4's across the bottom of my plywood to avoid warping.. Has worked so far....

    As Mountain Man said, whatever you do, good luck with it...
  6. Gary S.

    Gary S. Senior Member

    Thanks for the info. The gaps I left should take care of any expansion of the rails themselves.
  7. Mountain Man

    Mountain Man Active Member

    According to the manual put out by Model Railroader, Homosote has a number of faults, the two most serious being:

    1. Expansion and contraction dependent on temperature and humidity.

    2. Significant shrinkage in the first season of usage causing track to buckle.

    They recommend that anyone using this material under tracks restrict themselves to lengths of no more than 20".

    It isn't the plywood causing your problems.
  8. msowsun

    msowsun Member

    The trick is to do your track work in the winter when the wood has contracted due to low temperature and humidity.

    Then in the summer it will expand and created some gaps here and ther, but it will not kink.
  9. pgandw

    pgandw Active Member

    My experience with both plywood (1/2" as a subroadbed) and Homasote has been wonderful. Built it in coastal Oregon with rainy winters and foggy summers, and no humidity control. Moved it to Penasacola, Fl and Hollywood, FL with no air conditioning at the latter location. Had no problems with a single sheet of 4x6 of both Homasote and plywood cookie-cuttered to the track plan, and mounted to an L-girder frame. No painting of lumber, plywood, or Homasote.

    I readily acknowledge that just because I have had no problems doesn't mean others won't have any.

    The thing that I did differently which may have saved my bacon was hand-lay my track with no rail joiners. The Homasote was glued to the plywood with carpenter's glue (yellow), and the ties and ballast were glued to the Homasote with the same stuff, thinned 50:50. The glue may have provided some regulation of moisture absorbtion, just like paint. Next, because the rails were spiked, and not glued or soldered (except at turnout frogs), they could have shifted just enough to accomodate small amounts of expansion/contraction.

    I guess bottom line resolution for the original post, my recommendations would be:
    • control humidity with humidifier in winter, dehumidifier in summer. This will make the basement much more comfortable for you, too.
    • leave small 1/32" gaps at rail joints on straight track
    Just one of the recommendations may well be enough to solve the problem; take your pick. The 2 together should be enough in almost any circumstances, especially since you have already sealed the Homasote.

    my thoughts, your choices

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