Plywood used for MR surface.........

[lvanhen]

You could even use 3/4" ply, but that is not necessary.  The main consideration is what type of plywood are you using.  CDX is the cheapest type - used for sheathing.  Cabinet grade is the best.  The letters stand for the surface grade of the plywood.  A= smooth, no plugs, B= smooth with "football" shaped plugs, C= not very smooth but no voids, D= pretty rough with some exterior voids.  The X rating means exterior glue.  (try to get that info from some genius at Lowes or Home Cheapo!!)  1/2" is fine if it is supported every 16" or so, 5/8" is usually not available in the smoother surface grades, and still needs support every 16 to 20".  3/4" is available in the better grades, but check the price!!  The other thing to watch is the wood species.  Cabinet grades will usually be birch or oak, although cherry etc is available at much higher price than you need for a MRR.  Birch is better than oak, as oak has a surface grain.  Construction grades are usually douglas fir or yellow pine - AVOID THE PINE!!!!!  Pine will warp, is harder to nail into, and is heXX on saw blades!!.  If you choose 1/2" DF (doug fir) AC grade, you will not be sorry.  from a retired carpenter/cabinetmaker! 

[mobilman44]

Hi,

My existing 11x15 HO layout is "surfaced" with 1/2 inch plywood with 1/8 inch cork overlay.  Mainline trackage is spiked to regular cork roadbed, while yard and lesser trackage is spiked directly on the 1/8 inch cork overlay.  I am partial to plywood, one reason is that I use the "cookie cutter" method to change grades to access lower level staging or upper level main lines with 2 percent grades.  

After the Holidays, this 14 year railroad will be dismantled and a new one built in its place.  I am considering using 5/8 ply (or whatever is the next thickest over 1/2 inch), and will continue to use the cookie cutter method.

BUT, it occurred to me that maybe 5/8 inch ply would not work so well, especially since I am going to increase the grades to a max of 2 1/2 percent.  What are your thoughts on this???

Additional information:  The layout room is climate controlled, Homosote and/or foam is not an option, and I tend to build "bullet proof" benchwork.

Thanks!

Mobilman44