Plywood is kilm dried wood, why would you argue with their own instalation instructions, the Homosote company dose not come up with them for no reason, sure in a controled enviorment nothing moves but in uncontroled they do. This also brings up why I use 1x4’s in benchwork as their expantion is less than ply expanding mostly on the edges and not the ends and it is covered in foam only so that surface dosn’t move for all practical puposes with what we use it for.
I think the capitalized KILN was to draw attention to the correct spulng. It’s “kilN,” not kilM. That aside, fibers won’t expand with moisture as they are like hairs. Pulp will. Not sure about homasote since I have never used it.
I don’t know about hair but wood fibers expand and shrink with moisture.
Just looked it up, hair dose expand and contract with moisture, who knew?
All of this talk about how wood expands and contracts, not only dimensional lumber but also plywood sheet and homasote and whatever, ignores the specific issue raise by the OP - - - a single piece of flex track bending out of position. As I mentioned earlier, the very same thing happened to me.
Expansion and contraction of wood aside, the problem in this instance is a too tight connection of two sections of flex track giving way under pressure. If expansion and contraction of the plywood occurred, a whole lot more than just one section of flex track would be involved.
Rich
I’m thinking more that the latax caulk had a lot to do with what He experienced and that the sections in question were too tight from the get-go and the thin layed caulk couldn’t hold it in place any longer. I don’t use caulk for track adhesive, so I’m guessing.
Take Care! [:D]
Frank
No, what you don’t understand is nickle silver dosn’t expand much in the typical model railroad situation and just like on the 1-1 railroads, a kink can happen in only one place, the weakest. Plywood will cause proublems on a 4x8’ space and moreso on larger.
Reb, I am not contending that the nickel silver rail is expanding at all. A simple examination of a piece of flex track will reveal that if pressure is applied at both ends of the flex track, it will bend and give. So, if you place a section of flex track too tightly between two connecting sections of flex track, it will give under pressure. That is why it is not recommended to solder each and every flex track connection.
Rich
You guys don’t have track problems at all. Check out this link.
https://www.facebook.com/ScienceNaturePage/videos/762433897222204/
Mel
Modeling the early to mid 1950s SP in HO scale since 1951
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’ve only ever had this happen once at a rail joint to a bridge crossing. I took a bit more off each rail end and have never witnessed it again. I keep my layout room temperature down a bit, its in the basement.
There is no pressure on the ends if they don’t expand once installed, the ties have breaks in them and so there is not a problem there, cork dosn’t expand or dose foam (in the context of what we do), with the powers of elimination, that leaves one culprit, the wood!!! (and yes I did use multiple “!”)
Awesome!!!
Too bad that you are wrong.
This from a cork website:
Just like other wood products, cork is subject to the phenomenon of expansion and contraction in response to climactic conditions. During the heating season, moisture levels diminish, causing cork to contract. When humidity levels are higher, cork will expand.
Rich
Of course cork expands with moisture. If you take two brand new wine bottle corks and submerge one overnight in water, it will be noticeably larger than the dry one. That’s why we store our wine on end.
When lumber is cut at the mill, it comes off the green chain the way it was cut from the tree, with the grain all the same way. When you take it off the pile at the lumber yard, the grain should also be the same way. So when I built my 6’ x 18’ bench I did two things that I had learned along the way.
One was two use two 1" x 4"s as the main spine(s) of the bench instead of one 2" x 4". Making sure I flipped and turned end to end the 1" x 4"s so they faced with opposing grain before joining them together. This way as they dry out they keep each other in check and will remain straight. The second was to clamp all the 1" x 4"s together and run them through the Radial Arm saw making cuts for lap joints. These were then glued and screwed.
Lap joint.
Here is the underside… All done with lap joints and making sure the lumber had[:)] opposing grain where two 1" x 4"s make one 2" x 4".
This bench is as square and level as the day it was built.
Accually the cork we use only looks like cork bottle cork, is is way different and is not made from premium cork and has a lot of resin in it, also the way it is manufactured, so even though it is wood, for our purposes in the way we use it in the hobby (for the most part as I have seen some weird things), it’s expantion amount is not worth considering.