Ho Track Problems...

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

  1. jerry lewis

    jerry lewis New Member

    help! I live in vermont and each winter season my atlas flex track kinks after I spend each summer relaying it. My bench works is half-inch good quality plywood with homosote, cork road bed and atlas flex track. The first time the track developed kinks my modeler friends said that the homosote needed to be sealed. The next summer I tore up the track and homosote, sealed it both sides and relayed the homosote and track. During the winter the track kinked again, not quite as bad, but kinked. My layout is located in my basement that is a finished living area and heated during the cold season. At the moment I am not sure what to do. Some of my friends are telling me to use molded track such as Bachmann ez-track or Life-like power-loc with plastic roadbed because so systems will not kink, others tell me to use contact cement to lay atlas flex track and that will prevent any future problems. After relaying my layout twice now I want my next relaying (this summer) of the track to be my last! Can anyone help me with suggestions?
  2. MasonJar

    MasonJar It's not rocket surgery

    If sealing the homosote helped, it may be an indication that all the wood parts (benchwork, plywood, etc) are moving. Painting/sealing all that might be problematic, but you can try...

    The other thing to try is cutting gaps in the rail. While the rail does not move all that much, you need to allow room for the wood to which it is fastened to move. You may need to solder jumper wires across the gaps or add more feeders to the track. A cut the size of a dremel disk should be enough every three to six feet to prevent kinking. Cut in the summer (when the benchwork is theoretically at its "biggest") so that as the benchwork shrinks in the cold dry winter, the track will not kink - just the gaps will close.

    Hope that helps. Welcome to The Gauge!

  3. GN.2-6-8-0

    GN.2-6-8-0 Member

    What masonjar said is your best bet, Expanstion /Contraction is best solved by gaping your trackwork.. Even here in the southwest we have that problem...to a lesser degree of course but it still happens.
  4. Russ Bellinis

    Russ Bellinis Active Member

    It sounds like you are havingthe same problem we have in the Southwest, except your problem occurs in the opposite season. I suspect your basement is cool and dry in the summer when you do the bench and track work. Then in the winter, it is heated and probably quite a bit warmer than it is in the summer. When metal is heated, it expands. The only direction that the rail can go when it expands is to get longer. If the rail grows longer than the space available in the air gaps between rails, the rail kinks. Cut your gaps as has been suggested and solder jumper wires across the gaps but with a loop underneath to allow the railsto strecth without the jumper causing problems. If you continue to have rails kinking in the winter, cut more gaps and jumper them.
  5. Gary Pfeil

    Gary Pfeil Active Member

    I'd be quite sure it is not temperature but humidity that is the root cause of the problem. Humidity is higher in the summer and almost completely absent in the winter, due to the drying effects of the heating system. I had the same problem, and the advise to seal the roadbed is intended to help reduce the swelling of the benchwork due to humidity, as well as prevent it from shrinking too much when dry. I use plywood/homasote on most of the layout, and handlay a fair amount of track. I noticed the handlaid stayed put pretty well while the flex track went crazy. Basically what happened was the track nails I used for the flex track get pulled closer together in the winter dry season. This causes the kinks, as the rail has to bow to compensate for the track nails moving closer together. The handlaid has no track nails, just spikes much more often than track nails in flex track. And, the spikes are shorter, do not penetrate the roadbed to the subroadbed. Where I have flex track is hidden staging, and I don't even use homasote there, just plywood. I did observe that track laid directly on plywood kinks more than that on homasote, and that hand laid seems unaffected. Anyway, I removed some track nails in both directions from a kink, right during the heating season, and used a cutoff disc in a dremel to cut a gap. The thickness of the disc was enough to eliminate the kink, I then renailed the track. I've had no problems since, in any season. You may need to add feeders of course. Hope this helps.
  6. Ralph

    Ralph Remember...it's for fun!

    Jerry, I had similar issues with homosote. Painting it helped. Once my tracks were ballasted though I haven't noticed any problem.
  7. jerry lewis

    jerry lewis New Member

    Ralph--thanks for mentioning the ballast. I have not yet ballasted and of my layout and a friend just suggested that I do that also. Thanks to all that have replied thus far!!!
    Jerry (RUTLAND)
  8. steamhead

    steamhead Active Member

    Ballasting the track may help if the WHOLE track (ties and rails, maybe even the roadbed) is moving with the temperature changes. Ballasting will fix all that in place EXCEPT the rails. The metal will expand and contract with temperature changes. You will probably still need gaps to compensate for that.
    Just my $0.02...
  9. nachoman

    nachoman Guest

    how about using a humidifier in the winter? (or a de-humidifier during the summer?)

  10. Glen Haasdyk

    Glen Haasdyk Active Member

    I've never had a rail kink problem. But my benchwork is all made out of plywood with cork roadbed on top. Since I'm on the old DC block system for control, cutting gaps in the rails is standard so I can isolate the blocks. I wonder if not having blocks cut for DCC contributes to the problem?
    I also live in a semi-arid area (honest!) so humidity stays the same all year long.
  11. Mountain Man

    Mountain Man Active Member

    It can't be the plywood - because of the way it is made it does not expand or contract due to temperature or humidity changes. Look for another cause.
  12. Santa Fe Jack

    Santa Fe Jack Member

    I beg to differ. Plywood is wood, and it expands and contracts with humidity just as any wood does.

    This is precisely why I use foam insulation panels for the benchwork. It's dimensionally stable, wihc is important inthe southwest where it may be 20% relative humidity in the morning, jumping to 80% in a thunderstorm.
  13. pgandw

    pgandw Active Member

    My experience is a little different. Plywood expands and contracts far less than lumber, but still does so. In situations where the expansion/contraction is too severe for the other plys to handle (leave some unpainted 3 ply plywood out in variable weather for a while), glue or ply failure is often the result. Warping is a best case.

    Wood fibers swell when they absorb moisture, and contract when they lose moisture. This causes contraction/expansion to be much greater across the grain rather than along the grain.

    Wood boats - even those built of lapped plywood planks - are a great demonstration of this behavior. A wood boat that has been sitting on shore for a few months will leak like a sieve for the first few hours until the wood fibers start swelling. It's hard to find enough pumps to keep up. Within 6-12 hours the rate of leakage is cut in half. It usually takes about 2-3 days for a wood boat to completely stop leaking. All this despite the wood being well painted, but because of the drastic change in moisture content from one environment to the other. In fact, you cannot safely seal just one side of a wood hull because the uneven moisture absorbtion and expansion that now results will destroy the sealing resin and hull shape. Marine plywood can often be safely sheathed in fiberglass because the multiple thin plys laid at 90 degree angles reduce the propensity for warpage, and the waterproof glue in marine plywood further reduces moisture migration.

    Good wood furniture is thoroughly shellaced or otherwise coated during assembly to significantly retard moisture content changes. But cheaper wood chairs will often have their glue joints fail after exposure to a variety of humidity environments. Certainly has happened in my house. :curse:

    The difference in model railroad benchwork between dry winter heat (no humidifier) and summer natural humidity (no air conditioning) is often more than 1/16" over a 6-8 ft length if measured at the same temperature - even with a sheet of plywood on top. The difference will stress joints in the benchwork. If the benchwork sections are tightly assembled in the winter, the section joints will be "too tight" and stressed in the summer. If assembled tightly in the summer, the joints will have visible gaps in the winter.

    Painting will slow the migration of moisture into/out of wood down significantly, but does not stop it. Shellac and epoxy are the best "sealers" against moisture migration. But getting past the peaks of humidity without the maximum absorbtion due to the delay action of the paint is often enough to solve the problem in the model railroad world. Painting all sides/edges helps even more.

    The ideal is humidity control through air conditioning, dehumidification, and humidification. Your wood furniture will thank you, too.

    yours in benchwood and benchmarks
  14. Mountain Man

    Mountain Man Active Member

    Actually, it doesn't. Plywood is manufactured by layering the plys at right angles to each other, which creates enormous dimensional stability. I have been building structures out of wood and plywood for decades here in the Colorado high mountains, where extremes of temperature literally pull nails out of horizontal and vertical structures, and have never had a problem with plywood's dimensional stability. It is very popular with many woodworkers and furniture builders, and it is the choice for almost all roof decking - which is flush-fitted - for that specific reason.

    In addition, there are numerous railroad layouts in Colorado using plywood, and none of them have reported track buckling. They all specifically recommend plywood as the horizontal surface for train layouts, as do many of the magazines and offical "how-to" manuals.

    I would look for something else to be the culprit, somethng on top of the plywood and directly attached to the tracks, unless, of course, you actually installed interior grade plywood rather than exterior grade, which is not constructed using water proof adhesives, didn't seal it properly, and allowed it to absorb moisture from layout construction materials and chanes in humidity. I can certainly see where that might cause problems at some point, but you could hardly blame the plywood.
  15. jeffrey-wimberl

    jeffrey-wimberl Active Member

    Wanna bet? I work in a wood shop where wood furniture (cabinets, book shelves, desks, chairs and such as that) is made. Unless it's properly sealed, 1/2" plywood can expand or contract up to 5% of it's volume. 3/4" more so and more as you go through thicker sheets until you get to a thickness of 1 and 1/4" at 6.5%, at which point it expands/contracts less, but not by much. I've tested this myself by putting a C clamp on a piece of 3/4" untreated plywood before leaving the shop on what was to be a hot and humid night. The clamp was just tight enough to hold itself in place but could be pulled off without much trouble. When I came in the next morning, the plywood had expanded enough that the clamp left indentions in it a 16th of an inch deep. That's a lot of expansion. Most layout builders are going to build indoors (interior room, basemant, attic, garage) and aren't going to go for the extra expense of treated plywood. My layout base is treated 3/4" plywood and doesn't expand or contract to any significant degree, not even when hurricane Rita ripped part of my roof off and soaked part of the layout. Additionally, due to storm damage, the power was out for close to a month and daytime temps in my trailer went to over 110 degrees (it was hot enough that several spray paint cans under the layout exploded) and the humidity had the humidity gauge pegged for much of the time. I had a track kink in one place, where there was no gap in the rails. After cutting a gap with a hacksaw the kink immediatly went away. So, yes, sealed plywood doesn't expand or contract very much whereas untreated plywood can exand and contract quite a bit. As stated before, most layout builders won't think about using treated wood on an indoor layout. Applying a sealer to untreated plywood isn't enough because the interion plys will still not be treated. They will need commercailly treated plywood to get this level of protection from expansion and contraction.
  16. LocoIndy76

    LocoIndy76 Member

    Agreed... I worked in a lumber yard making deliveries and pick-ups. I've seen 7/16 plywood expand to almost twice it's thickness after it has been on a jobsite. This is lumber that has sit inside, collecting moisture while the house was being built.
  17. Mountain Man

    Mountain Man Active Member

    However, we have very low humidity in Colorado, and even less in the winter, whereas you have a lot more back in Indiana. How often does it rain in Indiana? 300 days of sunshine a year in Colorado.

    Average Colorado humidty is below 30%; many times it is around 20%, and it goes lower at times.

    Manwhile, I'm sitting here looking out my window at the two large doghouses I built 16 years ago. I built them just like a home, stick framing, flush-fitted plywood sheathing, flooring and decking, siding to match the house, roofing to match and so forth. Big dogs - wolf hybrids, in fact. These doghouses have sat outside through heat of up to 100 degrees and cold to minus 40. Snow has accumulated inside them and slowly melted in the spring, and I have never, ever had a single piece of that plywood buckle at a seam or joint, nor has a single nail pulled out if it.

    Our house was built with flush-fitted plywood sheathing and roof decking, and we don't have a single cracked drywall seam after two decades. Flush-fitted plywood sheathing has to buckle to accomodate the stated expansion, right? So I wonder where all that expansion went...

    As my dear old grandaddy used to say: "I knows what I knows and I knows why I knows it". You still need an explanation for why the professional layouts and club layouts in this area don't have to rebuild every year.

    Of course, the most obvious explanation for the trouble is one that no one has seen fit to mention - an unheated layout space. If temperature is kept fairly constant, you probably wouldn't have that problem.

    But hey - I'm just an ordinary guy, not one of you experts, and I'm not having the problem.
    My personal and sincere recommendation would be to contact your local railroad club and ask them how they do it. Or, I could dismantle those dog houses and send them to you in sections that don't warp or buckle. :)

    Whatever you do, though, good luck with it. :thumb:
  18. Gary S.

    Gary S. Senior Member

    I did a google search to find the expansion rate of different metals, but couldn't find anything. I am wondering just how much the 3 foot long nickel silver flex track rail will expand with a change in temperature, say from 40 degree F to 90 degrees F.

    And wow, a piece of 7/16" thick plywood expanded to twice its thickness? I'd have to see that!

    Seems like several people have had problems with homasote. Also, it seems that the extruded foam may be a very good material to use, it is pretty dimensionally stable, no?
  19. jeffrey-wimberl

    jeffrey-wimberl Active Member

    Foam solves some problems but creates others. For one, it cannot support the weight that the wood can. For another, you'll have static electricity problems out the wazoo. It won't hold nails and the use of some glues is problematic. How do I know this? Been there and done that. That's why my benchwork is treated wood, the top is treated plywood. On top of the plywood are a network of bare wires attached to the metal box of a grounded outlet. On top of this is a layer of 1/2" styrofoam sheets. I have no static problems with it because the static electricity is bled off through the ground wires. All this was learned the hard way, through trial and error over many years. As a result, I have a layout with the stability of wood benchwork, some of the flexibility of foam and the sound deadining properties of foam. I can stand on my layout and not cause any significant damage to it and I weigh 237 pounds. I use treated wood because it doesn't expand or contract to any significant degree due to humidity, which here runs over 70%. On your expansion of the rails, it doesn't have to be much to cause a problem. Even an expansion of 2% per inch can cause a kink in trackwork that is tightly fitted together. That's why I leave gaps in the rail joints and also cut additional gaps.
  20. Torpedo

    Torpedo Member

    0.016 inches by my calculation, which is not guaranteed to be accurate. The coefficient of thermal expansion for nickel silver is 16.2, according to a couple of web sources.

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