What exactly is the problem that almost all us face with our model railroad track seeming to change shape (length in particular), with temp & humidity variations? Can it be attributed to the track alone, or the subroadbed alone? ...or primarily to __?I've heard a number of folks who say the expansion/contraction of our rail itself is minuscule compared to that of the wood that most of our subroadbeds are constructed of.?... And that is the primary reason we experience what appears to be a change in track length, but its really the roadbed the track is attached to??
Brian
My Layout Plan
Interesting new Plan Consideration
That is why you use foam, covered with cork roadbed of the comerial type (you don't want good cork like from cork bottles as it is the bad cork used to make midwest cork roadbed that give you the right expantion and contraction. Last use caulk to put them together as it is flexable enough to take minor movement as any two different materials may be close to the same expantion rate but not exact. Forgot that you should use foam that has sat around awhile as foam shinks when first made (that is the 2% you hear about), after that it is fine. Also I like the beaded stuff as it dosn't tend to curl.
railandsail What exactly is the problem that almost all us face with our model railroad track seeming to change shape (length in particular), with temp & humidity variations? Can it be attributed to the track alone, or the subroadbed alone? ...or primarily to __?I've heard a number of folks who say the expansion/contraction of our rail itself is minuscule compared to that of the wood that most of our subroadbeds are constructed of.?... And that is the primary reason we experience what appears to be a change in track length, but its really the roadbed the track is attached to??
Yes, the lumber shrinks. Come visit some 100 year old houses with me at my work and I will show in great detail the effects of lumber shrinkage. One of the classic examples, in the early days of stick framing, in the Victorian period, they would tie wood framing to central chimneys. In those houses today, all the second floor floors slope away from the chimneys because the outer frame has shrunk, but the masonry chimney has not shrunk. Years later they learned to let the chimney "stand free" in the frame building.
The answers, use better lumber, use good methods, built trains in the same environment you would keep fine furniture in. No problems.
My train room is above my 32' x 40' detached garage. The building is not fully heated and cooled at all times but it is fully insulated. The the train room has a gas heat and A/C.
In the winter, I keep the train room thermostat at about 50 when I am not up there. In the summer I only run the A/C when I am up there, but there is good attic ventilation in the attic space above the train room. It gets warm, but generally not any hotter than the outdoor temperature. If we have a real heat wave, I have been known to keep the A/C on set at 80ish when I'm not up there.
No expansion and contraction issues in 22 years of Atlas track on homasote, on plywood and OSB, with botrh table top and open grid construction.
No matter the temperature, the humidity is pretty well controlled all year round.
I would never build a layout in a situation were wide swings in both temp and humidity could cause condensation. That is an invitation to expansion and contraction issues, and a long list of other problems.
Sheldon
One of the number one cause's of expansion/contraction of lumber is how it is cured. Kiln dried vs Air dried. Most big box stores sell Kiln dried lumber because it is faster and cheaper to get to the consumer. But it has been proven that Air dried is the best for MC (moisture contant) which is more stable in most environments, especially in high humidity use. The other materials used in the construction of a layout, cork, track even foam, have a minimul effect on a newly constructed layout. They move with the expansion/contraction of the lumber used in the framing.......period.
If really interested about what is going on...read this link:
https://journeymansjournel.wordpress.com/2016/10/23/air-dried-vs-kiln-dried/
When I used to own My own trucks, I hauled lumber out of Montana for a Mom & Pop lumber yard near My home here in IL. and never had any problems with lumber over the yrs. when and rarely got lumber from a Big Box store, it seems I always experienced some problems......warping being the number one problem.
Take Care!
Frank
So Sheldon you are saying what I have heard others say,...its not the metal track going thru these gyrations, its the lumber its attached to.
railandsail So Sheldon you are saying what I have heard others say,...its not the metal track going thru these gyrations, its the lumber its attached to.
Yes, at the temps we are talking about, metals do not expand/contract much at all. And humidity has no effect on metal.
Wood however expands and contracts based on both temp and humidity changes. Hot and humid it can get much bigger, cool and dry it can get much smaller, plus it is always shrinking from the day they cut the tree. But that shrinking slows after a few years and stablizes if the humidity is stable.
zstripe One of the number one cause's of expansion/contraction of lumber is how it is cured. Kiln dried vs Air dried. Most big box stores sell Kiln dried lumber because it is faster and cheaper to get to the consumer. But it has been proven that Air dried is the best for MC (moisture contant) which is more stable in most environments, especially in high humidity use. The other materials used in the construction of a layout, cork, track even foam, have a minimul effect on a newly constructed layout. They move with the expansion/contraction of the lumber used in the framing.......period. If really interested about what is going on...read this link: https://journeymansjournel.wordpress.com/2016/10/23/air-dried-vs-kiln-dried/ When I used to own My own trucks, I hauled lumber out of Montana for a Mom & Pop lumber yard near My home here in IL. and never had any problems with lumber over the yrs. when and rarely got lumber from a Big Box store, it seems I always experienced some problems......warping being the number one problem. Take Care! Frank
My layout is up for over 10 years. First, I let the wood aclimate to the room I was building the layout, for at least a week. My subroadbed is 1/2" plywood. I let that sit in the room for a week, then painted it, sealing it around all sides, top and bottom. Attached it to the wood frames. I use cork roadbed, and attach the track to it using track nails. No shrinkage, warping or any track bending out of shape.
Neal
The extreme option is to use steel studs for the frame and extruded foam. I had no problem with ordinary 1x4 framing with foam on top in a basement that wasn't heated or cooled, didn;t need much cooling, but in winter it could get pretty cool and all we had was a space heater. Humidity varied greatly, very low in winter, in summer it got pretty high despite a dehumidifier running pretty much 24/7 (hose drain into the condensate pump for the central air so it wouldn't shut off with a full pan of water).
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Funny how things sort of evolve. In the beginning I was seriously considering 2" foam subroadbed shelves held up with some pretty nice metal brackets from Home Depot. The 2" foam is not so readily availble here in FL, so I looked around for options.
Found what I thought was some decent plywood (called Blondwood) at Lowes. I monitored a stack of it at their store and i became less impressed,...and thought perhaps 3/4" rather then 1/2". I had also inherited a 1/2" piece of 4x8 from a friend and stored it in my carport, both on its edge and flat on the cement floor. I became even less impressed. It went thru all kinds of gyrations.
Then I ran across some 7 ply, 3/4" plywood from Chili being sold at Home Depot. It was the best looking stuff I had seen,....Radiata Pine. It was a little thicker (and heavier) than I had originally planned, but then again I am not supporting it with 3" wood framework on its edge as in many conventional benchworks, so a little extra thickness could be helpful for both stability and extra cantilivered strength. And if I paint it all around that should help seal it against some of the moisture of humidity.
So next my staging area track plans expanded, and began to interfere with those metal brackets I had selected orginally. Got a new idea that I would weld up my own out of surplus (scrap) steel bed rails/frames.oops, I was over at my local metal scrap yard this past Fri and noticed some hollow square steel tubing they use to mount street signs with. Its 2" square verses my flanged 1-1.25" bed rails, and its really strong, and its galvanized. So now I am definitely considering this stuff.
In the past I have critiqued that I often see benchwork for our model trains 'overbuilt'. Funny how I seemed to be headed in that same direction :)
A couple of years ago, I bought some 1/2" plywood. It wasn't until I had cut it into 3" wide strips (using the cookie cutter method for subroadbed), that I noticed that the wood wasn't level, no matter how much I adjusted the risers. After I removed the offending strips, I found that looking at the strips from the end, that the number of layers (plies) varied from side to side - 5 on one side and 3 or 4 on the other. When buying plywood sheets, I now take the time to look at the edges on all four sides. Luckily, the lumber supply house replaced the offending sheet, even though I had already cut it. Excellent customer service.
On another occasion, I purchased some 1x4s from Lowe's online. BIG MISTAKE! When I went to pick up the load, there wasn't a straight piece in the lot. I had them take it back inside, where I inspected each new piece.
Marlon
See pictures of the Clinton-Golden Valley RR
railandsail Funny how things sort of evolve. In the beginning I was seriously considering 2" foam subroadbed shelves held up with some pretty nice metal brackets from Home Depot. The 2" foam is not so readily availble here in FL, so I looked around for options. Found what I thought was some decent plywood (called Blondwood) at Lowes. I monitored a stack of it at their store and i became less impressed,...and thought perhaps 3/4" rather then 1/2". I had also inherited a 1/2" piece of 4x8 from a friend and stored it in my carport, both on its edge and flat on the cement floor. I became even less impressed. It went thru all kinds of gyrations. Then I ran across some 7 ply, 3/4" plywood from Chili being sold at Home Depot. It was the best looking stuff I had seen,....Radiata Pine. It was a little thicker (and heavier) than I had originally planned, but then again I am not supporting it with 3" wood framework on its edge as in many conventional benchworks, so a little extra thickness could be helpful for both stability and extra cantilivered strength. And if I paint it all around that should help seal it against some of the moisture of humidity. So next my staging area track plans expanded, and began to interfere with those metal brackets I had selected orginally. Got a new idea that I would weld up my own out of surplus (scrap) steel bed rails/frames.oops, I was over at my local metal scrap yard this past Fri and noticed some hollow square steel tubing they use to mount street signs with. Its 2" square verses my flanged 1-1.25" bed rails, and its really strong, and its galvanized. So now I am definitely considering this stuff. In the past I have critiqued that I often see benchwork for our model trains 'overbuilt'. Funny how I seemed to be headed in that same direction :)
Water over the dam now, I have my new materials