Best Plywood for a Flat Surface

Just my opinion, do what ever you want, but the best plywood is not plywood it is MDF. Does not warp and does not splinter, I also think it is easier to cut and sand.

But if MDF gets wet, very not a drop or two, it will swell and you are screw-ed! In My Opinion from making benches for my Drill Press, etc.

And it is very heavy! So make sure if you use it that the framework is strong enough.

#3 or #4.  I agree, they are the best. 

MDF, very flat and smooth, but heavy and not sure how well it does in the long run.

When shopping for plywood at HD, I often that the straightest, flattest sheets are somewhere in the middle of the stack

1/2" is fine. The problem is the lack of under structure. i built mine with stringers 16"

on center and used $9.95 OSP board with homasote. After 15 years it is as flat and level as can be. If I did it over I would leave out the homasote as all the track is on vinylbed roadbed. This for a sheet of plywood on a table.

If doing a cookie cutter type layout I would use 3/4" plywood. Pretty plywood does not make it stronger. Save your money.

As a cabinet maker this is what I use: my work benches are all ACX plywood. Smooth top, who cares about the underneath and the exterior glue keeps it stable. I have benches in my workshop that are 15 years old and are as smooth today as when I built them. For cabinet work it is cabinet grade birch or oak. And Flash has it right, look thru the pile don't take what is on top.

I would think that what you're going to mount the plywood to would determine how flat it's going to be.  If you're doing a "legless" layout, a 2 x 4 or 1 x 6 framework under the plywood, screwed in place, would keep it flat.  Don't skimp on the screws.  I used 1/4" thick plywood on my table top layout, but when doing it over again, I think I would use a thicker piece to give it a more uniform flatness to compensate for warped framework pieces that you don't notice until you put something flat on them.  If you're going to landscape the layout, the finish on the plywood is not really an issue, so go for the standard stuff.  I think the key is to make sure the plywood is well secured to a framework base which should have plenty of cross members to tie into.

Mike 

for 60 years I have always used B/C 1/2 inch plywood and never had a problem.  I do not understand Cabinet grade being cheaper than the rest but I would have to use that if available

I think the OP is talking about surface smoothness. I would recommend either birch or maple veneer. Sometimes Home Depot has 3/4" or nearest metric equivalent of Maple for 25 bucks a sheet.

Pete

Don't forget to look at the old school, smaller local lumber yard. Not all plywood is created equal.

I would take a cabinet-maker's advice.

However, to add my own 2 cents and 69 years of experience...the more plies, the better.  And drawing from the middle of the deck does not always work....especially in humid environments.

Also, our local lumberyard....almost 100 years in business...once told me to consider 'ping-pong' table plywood...5'X9' PLUS highest quality plies/veneer, made flat, shipped flat, stored flat, stays flat.....for obvious reasons.  Not cheap.  Not always available in smaller yards.  But the better local cabinet makers often prefer the stuff for the quality reason....AND it frequently enables one-piece panels in situations where a 4X8 just doesn't quite make it.

Tricks of the trade, I guess. 

FWIW, always.

BTW...I like MDF for certain situations....but not layout roadbed.

KD

My recommendations (based on some hard lessons learned):

• 5 ply or more is better.  Get a good quality piece of wood, sanded on one side.
• 1/2" thick or better.  Particularly true if you are going to use it for cookie-cutter roadbed.
• Shellac or varnish the plywood before using.  Will cut down moisture induced mis-behavor.
• MDF is extremely heavy.  Stay away from it.
• In our area, Home Depot tends to have worse lumber than Lowe's.  However, I would definitely check out the local lumber yards.  They seem a bit more motivated than the big boys.
• This isn't a place to skimp or save money.  Track performance is directly affected by table-top / subroadbed.  And it is not easily fixed or band-aided.

George

I uses a MDO board.  Medium Density Overlay.

Added link to MSDS sheet.

If you use MDO please note that MDO plywood dust is toxic and breathing protection (dust mask, goggles and the like) is required when working with it.

Read more: http://www.ehow.com/about_6466..._.html#ixzz2kZ92U2Gm