Track question

Discussion in 'HO Scale Model Trains' started by foulrift, Jul 24, 2008.

  1. foulrift

    foulrift Bob

    I have noticed that with temperature changes in the room where my layout is that there seems to be expansion and contraction of the track.Sometime there are gaps in the rail and sometimes there are none.I had just gone over all the track to make sure there were no gaps and tacked the track down with ACC.Is this normal and is it a concern?Thanks Bob:confused:
  2. Russ Bellinis

    Russ Bellinis Active Member

    The metal in the rails will expand and contract with temperature changes. Humidity changes will have more effect on bench work. If you have large temperature swings, the rails will expand and contract. If you don't leave enough gap when it is cold, the rails will make "S" shapes to absorb the expansion. Your acc or anything else you use to try to stop the expansion won't make any difference. The only solution to the problem if you want to eliminate expansion and contraction of the rails is to insulate the space and then use heating and ac to keep the temperature constant. If you have a problem with humidity causing the bench work to change, the solution is to paint all of the lumber on all sides to seal it from moisture.
  3. foulrift

    foulrift Bob

    Thanks Russ-The bench work is painted.What I think I'm going to do is run the engine.If there are no problems then when all the track is down I'm going to solder the joints.I only used the ACC to hold the track from moving until I get the ballasting done down the road.The layout is in my bedroom and as far as insulating the area-can't do anymore than what insulation there is in the room-I rent so I'm stuck with what I have.Thanks again-Bob
  4. eightyeightfan1

    eightyeightfan1 Now I'm AMP'd

    Thats what I did...Solder all the joints. And I paid for it.
    My layout being in the attic, it's always under some sort of tempature change. Hot during the day, cooling of at night. With all the joints soldered, I had at least fifteen feet of flex track kink, and pull its self off the ballsted road bed.
    When I repalced the damaged track, I left it all unsoldered. And unsoldered the track that was soldered.
    So far, no problems
  5. Dave1905

    Dave1905 Member

    The change in the length of the rail is very, very small. Most of the time the kinks in the track is caused by the swelling/shrinking of the wood roadbed underneath. It changes length 10 times more than the rail does.

    Dave H.
  6. Gary Pfeil

    Gary Pfeil Active Member

    I agree with Dave
  7. foulrift

    foulrift Bob

    So are you guys saying that I shouldn't solder the joints and to just let the track do it's thing? If so,that goes against everything I have read in other threads.In many threads most everyone solders their rail joints mainly to insure good electrical flow.I guess I will have to re-think this.I have tested the track unsoldered and the loco seems to run OK.
    I suppose I can run it the way it is for now,I do however plan on adding some feeder wires.Thanks again-Bob wall1
  8. Dave1905

    Dave1905 Member

    You shouldn't solder EVERY joint. Many people solder joints in the curves to keep a smooth curve. Leave gaps/joints every 2-3 rail lengths. Don't rely on the rail to carry your current, put in feeders every or every other piece of flex track.

    Dave H.
  9. foulrift

    foulrift Bob

    Thanks Dave and everyone else.I neglected to mention that my layout is small-only 2'x8' with no real curves mainly straight track.I may solder a few joints here and there except near switches-I want them to float.There are areas with track added on to complete a run and it is in these areas where I'll solder plus the feeders.As I mentioned before I have test run my engine with the track the way it is and it ran fine with no noticeable power drop but just to be sure I'll do as I mentioned. Thanks again- Bob
  10. nkp174

    nkp174 Active Member

    Real railroads leave expansion joints. You'll also see them on bridges as well. So if you lay the track in a room at 55F, 3 pieces of flex track will need 1mm to expand at 85F. Our Nickel Silver rail is more responsive to temperature changes than the steel rail of full sized railroads.
  11. doctorwayne

    doctorwayne Active Member

    A lot depends on the conditions in your layout room. My layout is in an unheated/uncooled room in the basement. The walls are well-insulated and it's usually "comfortable" in the room, although a long spell of cold weather can make it a little chillier than I like. There's a suspended ceiling in place, and the floor is unpainted concrete. There is a dehumidifier running, elsewhere in the basement, during the summer.
    I soldered all of my rail joints together, then cut gaps where I needed to be able to isolate track sections. Not counting sidings and passing tracks, there is about 145' of mainline track in service, with another 45' seldom used (it currently dead-ends in the middle of nowhere). Another 65' of track is needed to complete that track to the northern terminus of the line. While there is a bus wire for the fascia-mounted throttle jacks, the power is connected to the track only at the power pack. I've had no problems with expansion or contraction of either the rails or the unpainted wood used to construct the layout, and no problem with current drop-off as the trains travel away from the power source, which is DC. Other than an occasional dusting and vacuuming (well, once in 15 years for the latter :rolleyes: :-D), not much in the way of maintenance, either. I don't clean track, ever, unless I've been working on scenery in a particular area.

  12. Russ Bellinis

    Russ Bellinis Active Member

    I hate to disagree with you, Dave; but temperature swings will change the rails significantly. The modular clubs in So. Cal. use to set up a few times a year in indoor shopping malls before the malls discovered that they could rent the space we used to kiosks selling all sorts of stuff for extra income. We had one member who used to constantly harp on the idea that we should butt the rails tightly together at the interface joiner tracks to eliminated derailments between modules. He was in charge of the set up at one show and so he proceeded to show us how the layout should be done. We were set up under a sky light and set up at after dusk on Friday night. On Saturday, morning track was kinking from rail expansion all along the West side of the layout (sun shining in from the East toward the tracks on the West side). The joiners were removed, and trimmed to allow for expansion. As the sun moved across the skylight warming different parts of the layout, we kept getting more kinks that were repaired by removing, trimming, and replacing joiner tracks. Eventually all of the joiner tracks were replaced. There was no change in humidity, or evidence of the wood expanding or contracting. I am not talking about a big gap here, just the thickness of a business car between the module tracks and the joiner tracks on both ends of the joiner track, but without that little bit of expansion space, we had kinks and buckles all over the layout.

    By the way, this indoor mall was air conditioned, and never got uncomfortably warm. The problem was entirely due to solar gain in the specific sections of the layout that the sun was shining on directly. It never got warm enough to cause any other problems with scenery or building models on the modules, just the track.
  13. Dave1905

    Dave1905 Member

    Brass has a coeffieint of expansion of about 10 in/in-Degr F x 10(-6). (10 inches per inch and degree F of temp change times ten to the -6).

    For a solid 30 ft long piece of rail (and nickel silver is basically brass) and a 20 degree temperature swing (room =72, rail = 92) that would be an expansion of .078 in, for 30 degree swing it would be .11 in. So on a modular layout with a relatively long run of track very tight track, that .078 could cause a problem. On a smaller home layout with shorter continuous sections of track, not as much. On a 20 ft run with 20 degr swing you are looking at .05. Soldering every 2 or 3 pieces of flex track gives you runs of only 9 ft max and and expansion of .022. Easily compensated for with a small gap. A sheet of plywood can shrink up to .22" over the length of the sheet (10 times the expansion of the rail) but it is affected by changes in humidity, not temperature.

    So yes in a long run of rail a large temperature swing can cause problems. But a large humidity swing can cause even larger variations in wood/plywood dimensions.

    Dave H.
  14. seanm

    seanm Member

    That is good information Dave! Thanks! What is the wisdom on a helix? I would think that all the rail should be soldered... but maybe not. How would you hold the rail in place if there was a gap in a constant curve. My helix will need 4 pieces of flex per revolution and be 2.5 revoultions.
  15. foulrift

    foulrift Bob

    Dave-What's your point? All that means nothing to me. My layout is a small switching layout-2'x8'-no curves to speak of.I have deceided to solder the joints and add feeders.
  16. foulrift

    foulrift Bob

    I think it's time to put this thread to bed.My thanks to those of you that actually gave me the answers/information that I was looking for. Bob
  17. Russ Bellinis

    Russ Bellinis Active Member

    Reading Dave's post, he suggest soldering no more than 3 pieces of flex track, and then allow for expansion of .022" to the next piece of flex. For perspective, 1/4 inch is .250". .022 is probably close to the thickness of a business card. In a helix that will use 4 pieces of flex I would lay it out as follows. Start at the bottom or top as you wish. It probably works better to start at the bottom and build your helix base as you lay the track to the top. If it will require 4 pieces of flex to complete the helix, don't forget that you need to start your helix about 6 inches to a foot from the end of your flex track and end it the same way. You should do that to eliminate any vertical curves at the beginning or end of the helix. I would use unsoldered rail joiners between the last straight section and the first flex track going into the helix. Put a business card vertically between the ends of the rail to give yourself a gap for expansion. Start laying out your curve into your helix, but stop about 6 inches or so from the end of the curve. Since the inside rail is going a shorter distance around the curve than the outside rail, the inside rail will protrude a few inches out of the flex as the outside rail comes to the end of the tie strip. The other possibility if your flex track has a moveable rail and a fixed rail is that the outside rail will have pulled back a few ties from the end. Cut the connectors between the ties under the rail to allow the last few ties to be slid back away from the solder joint. Put on a rail joiner at the end of the rail and connect the corresponding rail from the next piece of flex track into the same joiner after cutting the connectors on the ties under the end of the new piece of flex. Slide the inside rail of the new piece of flex forward and then slide the protruding piece of rail into the tie strip of the new flex. Use rail joiners and solder the 2 pieces of flex track together. You should now be able to continue laying out your helix curve as you continue building your helix. At the next connection of flex track, you will need to put in an expansion joint. Again slide your tracks in the new piece of flex as needed to fit the protruding piece of rail to the new piece of flex. Install rail joiners between the rail ends and use a business card to set your gap between the 2 pieces of flex. Continue to lay out your helix and add the next piece of flex track the way you did the first one with a solder connection between the 2 pieces of flex. You could cut off your flex track flush when one piece sticks out too far after making the curve, but you will get smoother track if the joints are staggered a bit through the curves. A business card or a piece of thin cardboard like a cereal box will provide an adequate gap for expansion at the ends of tracks that are not soldered.

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