best for cookie...

[NCMRailroad]

Hi Folks,
Just wondering... what is the best thickness of plywood for doing the cookie cutter style?
rgd's,
Wm (NCMRailroad):thumb:

 

[shaygetz]

1/2" minimum, 5/8" better, 3/4" is the best if you can afford it.

 

[Russ Bellinis]

The thickness needed will be detrmined by how close together you put the supporting structure under the subroadbed. If you have cross members under the layout every 12 inches that can be used to support a subroadbed support, then you can use a thinner plywood. If you put your cross members on longer centers, you will need thicker plywood to keep the sag out of it.

 

[MasonJar]

On my first (4x8) layout, I used 1/2" over a grid with maximum 16" centres (most were significantly less). I found that the 3/4" did not bend as easily. This could be a good thing though, as it will stop you from making grades too steep too quickly!

Andrew

 

[ezdays]

You don't say how large a layout or what scale. I have a N scale 2' x 3' that I bought with a bunch of other stuff at a thrift store and they used 1/4" plywood for their cookie-cutter layout. They also supported it every few inches so there's sufficent support for that thickness.

 

[fsm1000]

Depends on how far apart the supports are:
1/4 for 12 inches
1/2 for 18 inches
3/4 for 24 inches
and up to 3 feet for one inch
Also the width should be a minimum of three inches.

Is that what you were looking for?

 

[gottaBreal]

What do you suggest for under Foam board?

 

[MasonJar]

What do you suggest for under Foam board?

Depends on the thickness of foam, and the weight of track, trains and scenery. For HO scale, using lightweight (foam) scenery, and 2" foam, I would suggest that you space your grid no more than 24" on centre.

These standards come from www.hotrak.ca, the local modular club.

Andrew

 

[gottaBreal]

im going to build 1x4 box frame on 16" centers going from 1' at the narrow end to 3' at the wide end. Its about 11' long as well. Id like to use 4" thick foam board. SO do I need to put down 1/4" plywood under the foam and then glue the foam down?

 

[Russ Bellinis]

im going to build 1x4 box frame on 16" centers going from 1' at the narrow end to 3' at the wide end. Its about 11' long as well. Id like to use 4" thick foam board. SO do I need to put down 1/4" plywood under the foam and then glue the foam down?

Are you planning any elevation changes beyond the 4 inches you can get from carving 4 inch thick foam? Foam doesn't bend very well at all.

 

[MasonJar]

im going to build 1x4 box frame on 16" centers going from 1' at the narrow end to 3' at the wide end. Its about 11' long as well. Id like to use 4" thick foam board. SO do I need to put down 1/4" plywood under the foam and then glue the foam down?

No. In my previous post, I meant that all you need is the grid. With a grid 16" on centre, made from 1x4's you will not need a full sheet of 1/4" ply underneath, unless like Russ says, you intend to carve away the majority of the foam (i.e. down to less than 1-2" thin).

You will likely want some sort of facia though, to protect the edge of the foam. You cannot recess 4" foam (actually 4" thick) inside a frame of 1x4 (only 3.5" high)

Andrew

 

[gottaBreal]

Are you planning any elevation changes beyond the 4 inches you can get from carving 4 inch thick foam? Foam doesn't bend very well at all.

Not really I think Im going to build this shelf layout and give foam a try. Its just going to be a switching area so i dont really need elevation change.

 

[gottaBreal]

No. In my previous post, I meant that all you need is the grid. With a grid 16" on centre, made from 1x4's you will not need a full sheet of 1/4" ply underneath, unless like Russ says, you intend to carve away the majority of the foam (i.e. down to less than 1-2" thin).

You will likely want some sort of facia though, to protect the edge of the foam. You cannot recess 4" foam (actually 4" thick) inside a frame of 1x4 (only 3.5" high)

Andrew

Ok so as long as im not going to go under the 2" mark of the foam I dont need anything under it. Hmmmm care to tell me how to attach the foam onto the 1x4 grid?

And yes the front edge will have a nice Facia to hide the 1x4 and the foam board.

 

[Russ Bellinis]

Ok so as long as im not going to go under the 2" mark of the foam I dont need anything under it. Hmmmm care to tell me how to attach the foam onto the 1x4 grid?

And yes the front edge will have a nice Facia to hide the 1x4 and the foam board.

I would use 1x6 on the front and ends of the frame with a 1x4 in the back next to the wall.
A 1x6 will not be much heavier than a 1x4 nor will it cost a lot more, but now you have a 5.5 inch depth instead of a 3.5 inch depth. Screw and glue 1x1 strips around the inside of the frame near the bottom. If you are going to mount under table switch machines like a Tortoise machine, I would put a sheet of 1/8 inch luan plywood door skin, or 1/4 inch cdx plywood (cheapest grade you can buy) cut to just fit inside the frame and screw it down to the lip underneath. In that case depending on whether you use the luan or the 1/4 inch ply, locate the strips so that you have exactly 4 inches from the top of the plywood to the top of the frame. Now the foam will drop right in flush with the top of the frame, and the plywood & furring strips will keep it from falling through. If you check out the tool dept. at Home Depot, Lowes, Ace, etc, you should be able to find a long 1/4 inch drill bit. I'm talking one 6-8 inches long. When you put down your track, anyplace you want a switch with an under table machine, mark the center of the throw bar where the switch linkage will hook up on the top of the foam and drill straight down through the foam and plywood. Then you can just fasten your under table machine to the bottom of the plywood under the foam and run a piano wire up through the 1/4 inch hole to the switch throw bar, and bend it ove the bar to hold it in place.

By the way, 1x1 inch cross members fastened to the the furing strips from the outside of the framework with 2 or 3 inch long drywall screws and fastened to the plywood or luan with 5/8 inch drywall screws combined with the rigidity of the foam board will make the benchwork plenty strong for the job. If you want to hide the screws and provide a finished facia, you can glue masonite to the front & ends of your benchwork.

 

[gottaBreal]

Very well put Russ thanks for all the input.