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1/2" Plywood vs 3/4" Plywood?

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1/2" Plywood vs 3/4" Plywood?
Posted by kenben on Friday, August 16, 2019 1:22 PM

Finally building my first HO layout, 8ʻ x 6 1/2ʻ. For the subroadbed is 1/2" or 3/4" plywood better? Iʻll buy 2 sheets of 4ʻx8ʻ prime plywood and they will be cut up a bit for track elevations etc.

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Posted by doctorwayne on Friday, August 16, 2019 2:23 PM

Most of the sub-roadbed on the main level of my layout is 3/4" firply, good one side.  Most of it is also cut-out curves of varying radii, supported by risers...

The few areas of straight track are on either the same plywood cut into strips, or on 1"x2"s or 1"x4"s.  Staging yards and all of the partial upper level are on sheet plywood of various thicknesses.

If you're making a table-top style layout, 1/2" or even 3/8" plywood, properly supported, is suitable, while cookie-cutter style roadbed is better, in my opinion, in 3/4" plywood.

The dimensions of your layout may cause some issues with "reach", especially once you have scenery and structures in place.

I'm not sure what you mean by "prime plywood", but good-one-side in most grades is sufficient.  Once the scenery and ballast is in place, the plywood won't be visible.

Wayne

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Posted by hardcoalcase on Friday, August 16, 2019 3:48 PM

For the subroadbed, I use 1/2", 4 ply plywood, on risers spaced about 14" to 16" apart, and over three layouts, I've been well satisfied with it.  Its sturdy enough for me to lean on it if I need to do a long reach over the layout.  IMHO, 3/4" ply for subroadbed is overkill.

I used salvaged 3/4", 8 ply plywood, ripped to 1" x 4" lumber for the benchwork which is a combination of open grid and L-girder, and I highly recommend it.  Using new 8 ply is about the same cost as buying prime stick lumber, and its virtually free of warp or distortion issues.

Jim

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Posted by SeeYou190 on Friday, August 16, 2019 4:27 PM

I always spend the extra and over-build. 3/4" plywood only for me.

.

-Kevin

.

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by kenben on Friday, August 16, 2019 6:17 PM

Wayne, reach is not an issue. There is a center open area that I "could" place a pop-out area for scenery in the future. But everythign is within a 2ʻ reach.

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Posted by RR_Mel on Friday, August 16, 2019 6:33 PM

Well I normally over design and build everything but . . . .   When I needed to elevate my layout after many hours of thinking I decided it was a lot easier to go with ¼” plywood.  That was back in 1988 and the ¼” plywood has worked perfect since day one.
 
I used 4” width for the roadbed and 1”x 4” bracing between the basic ½” plywood base.  My layout is HO scale 14’ x 10’ x 33” off the floor, the grade goes from 0 to 10” in 25’ or about 3.3% all on ¼” plywood.  It levels out at 10” then back down on a 30” radius helix back down to the basic level.
 
I also used ¼” plywood for the helix with 1”x 2” side bracing, again no problems after 31 years.
 
I did use a lot of wood screws and Carpenters glue on all of my layout.  Too make things even more acceptable to problems my layout is built on casters and I move it around the garage and even out onto the driveway when I need to clean the garage floor.  Out on the driveway it is a neighborhood kid magnet.
 
So I would say it depends on your carpentry skills when it comes to sizing the plywood.  I would say that ¼” is most likely half as hard to work with compared to ½” and 75% easier than ¾” plywood and a lot less weight.  The cost would also be a lot less.
 
 
 
Mel
 
 
My Model Railroad   
 
Bakersfield, California
 
I'm beginning to realize that aging is not for wimps.
 
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Posted by doctorwayne on Friday, August 16, 2019 6:34 PM

kenben

Wayne, reach is not an issue. There is a center open area that I "could" place a pop-out area for scenery in the future. But everythign is within a 2ʻ reach.


Okay, that makes sense.  I was going only by the dimensions.
 
Wayne
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Posted by UNCLEBUTCH on Friday, August 16, 2019 6:46 PM

 Depends on how mutch money you want to spend. They will both do the job,as well as Mel stated 1/4.  or3/8 or 5/8  I've seen OSB used also.

IMHO 3/4 is over kill and wasted money,along with ''prime''

Was it me, 2in. foam.

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Posted by Mark R. on Friday, August 16, 2019 6:47 PM

I'll always remember a comment made by Tony Koester many years ago when asked why he used 3/4" plywood for his road bed. His response was that nobody made 1" plywood.

Mark.

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Posted by SeeYou190 on Friday, August 16, 2019 7:05 PM

Mark R.
Tony Koester many years ago when asked why he used 3/4" plywood for his road bed. His response was that nobody made 1" plywood.

.

That is exactly how I feel too.

.

-Kevin

.

Wink Happily modeling my STRATTON & GILLETTE RAILROAD. A Class A line located in a personal fantasy world of semi-plausible nonsense on Tuesday, August 3rd, 1954.

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Posted by ATLANTIC CENTRAL on Friday, August 16, 2019 7:14 PM

3/4" Birch plywood here, and benchwork framing with 1x4 Poplar, yes, like a piece of furniture........

Homasote sheets for yards, homabed roadbed elsewhere.

Foam? What is that?

But seriously, a lot of different methods work fine. Thicker plywood means fewer supports, better lumber means easier construction and more stablity in lots of ways.

I have used laminated OSB, every thickness of plywood, dimensional lumber, build framing from high quality Poplar and surplus 2x4's.

And I have used every framing method, open grid, L grider, table top, cookie cutter, etc.

And I always build benchwork that can support my 200lbs........

My new layout will be a combination of open grid and table top benchwork, which will also mean a few "cookie cutter" transitions.

Still don't understand the attraction of foam? But to each their own. 

Sheldon

    

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Posted by snjroy on Friday, August 16, 2019 10:24 PM

I went with 3/4". Thicker ply allows you to do a lot of hard banging without damages... it also allows you to reduce the number of supports. But it makes it more complicated when installing Peco switch motors under the layout.

Simon

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Posted by betamax on Friday, August 16, 2019 10:28 PM

I actually did some rough testing of the deflection in a 5' by 2.5' frame built out of Baltic Birch. The boards were 3.5" wide.

For the test I piled precision weights on the center of the frame, with a total of 73.8 lbs. in the center. Using a laser I marked a zero point, added the weight, and measured the difference.

With the frame made of 12mm plywood, with five crosspieces of 12mm, the deflection at the center was 1/8".

Same construction with 18mm: 1/16".

 

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Posted by carl425 on Friday, August 16, 2019 10:39 PM

One more vote for 3/4.

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by UNCLEBUTCH on Saturday, August 17, 2019 9:44 AM

betamax
I actually did some rough testing of the deflection in a 5' by 2.5' frame built out of Baltic Birch. The boards were 3.5" wide. For the test I piled precision weights on the center of the frame, with a total of 73.8 lbs. in the center. Using a laser I marked a zero point, added the weight, and measured the difference. With the frame made of 12mm plywood, with five crosspieces of 12mm, the deflection at the center was 1/8". Same construction with 18m

  How is it even possible, to get 70lbs of MR stuff in a 5ft span ?

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Posted by BroadwayLion on Saturday, August 17, 2019 9:53 AM

Eh! Plywood? Watt is this plywood of which ewe speak.

 

LION used 1/2" Celotex (The OLD kind made before the advent of fire codes). Today's Celotex is a company making many things, but not the "old Celotex"

 

This material is lighter than Homasote, and much less dense. It is easier to cut, and seems to also be mor rigid than Homasote.

 

Lion use 16" centers for support. This is important since that is how much space is needed to get a drill between the supports.

I used up all ten sheets on my layout. I was over in the Gym the other day and saw several more sheets of the stuff. The seem to have torn out a ceiling someplace.

 

ROAR

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Posted by York1 on Saturday, August 17, 2019 10:30 AM

ATLANTIC CENTRAL
Still don't understand the attraction of foam? But to each their own.

It's very lightweight, it's easy to cut, it's rigid and strong, and it can be shaped and glued into just about anything I want without using a lot of tools.

I also think some people have regular old styrofoam confused with the extruded foam we use.

Saints Fan John

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Posted by ATLANTIC CENTRAL on Saturday, August 17, 2019 10:49 AM

York1

 

 
ATLANTIC CENTRAL
Still don't understand the attraction of foam? But to each their own.

 

It's very lightweight, it's easy to cut, it's rigid and strong, and it can be shaped and glued into just about anything I want without using a lot of tools.

I also think some people have regular old styrofoam confused with the extruded foam we use.

 

I work in the construction trades, I am very familiar with the product, that is why I will not use it for model trains. In my business of restoring old houses we avoid it as well.

It will not support my weight, my benchwork must support me if necessary.

Easy to cut?, you mean messy to cut.

Lightweight is not a requirement or advantage for me.

Glad it works for you.

Sheldon

    

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Posted by ATLANTIC CENTRAL on Saturday, August 17, 2019 10:53 AM

UNCLEBUTCH

 

 
betamax
I actually did some rough testing of the deflection in a 5' by 2.5' frame built out of Baltic Birch. The boards were 3.5" wide. For the test I piled precision weights on the center of the frame, with a total of 73.8 lbs. in the center. Using a laser I marked a zero point, added the weight, and measured the difference. With the frame made of 12mm plywood, with five crosspieces of 12mm, the deflection at the center was 1/8". Same construction with 18m

 

  How is it even possible, to get 70lbs of MR stuff in a 5ft span ?

 

Easy, when I climb a short step ladder, put down a protective mat and lean on the layout, a large percentage of my 200lbs is now supported by the benchwork.

I like deep scenes, most of my new layout will be 3-4 feet deep, with most trackage in the front 30".

Sheldon

    

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Posted by selector on Saturday, August 17, 2019 11:53 AM

I use 1/2" G1S for both decking and sub-roadbed.  I don't see the necessity to pay for anything more substantial because I have no problems with my method of construction or with shifting materials subsequent to starting scenery (with all that water) and running trains.  In fact, I have used 3/8" finish-quality ply when, due to normal variance in construction, I need an extra bit of clearance overhead.  I just keep the supporting elements to within a span of about 12".  So far, so good.

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Posted by York1 on Saturday, August 17, 2019 12:29 PM

ATLANTIC CENTRAL
Easy to cut?, you mean messy to cut.

 

Not to prolong a point, but when I score one side of the extruded foam, then snap it, I end up with less mess than the sawdust involved in cutting plywood.

As you and others have said, what works for you ...

Saints Fan John

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Posted by UNCLEBUTCH on Saturday, August 17, 2019 1:18 PM

ATLANTIC CENTRAL
Easy, when I climb a short step ladder, put down a protective mat and lean on the layout, a large percentage of my 200lbs is now supported by the benchwork

 Well OK, but I and I"M sure others have never needed to use the layout as scaffolding.

Perhaps thouse who do should issue a disclamer stating such, I think that would help newbes not to over think, over build, and overspend,on benchwork thats not normally needed.

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Posted by ATLANTIC CENTRAL on Saturday, August 17, 2019 2:51 PM

UNCLEBUTCH

 

 
ATLANTIC CENTRAL
Easy, when I climb a short step ladder, put down a protective mat and lean on the layout, a large percentage of my 200lbs is now supported by the benchwork

 

 Well OK, but I and I"M sure others have never needed to use the layout as scaffolding.

Perhaps thouse who do should issue a disclamer stating such, I think that would help newbes not to over think, over build, and overspend,on benchwork thats not normally needed.

 

I guess that depends a lot on the layout design. If you are happy with 2' deep shelf layout concepts, then it is very likely you will not need benchwork as strong as mine.

But I like deep scenery, my new layout will be around the walls of my basement with two peninsulas out into the space. The benchwork along the walls will mostly be between 3 and 4 feet deep. The peninsulas will be 8' wide to accommodate the 40" radius and larger curves on the double track mainline.

There will be access hatches in places, but climbing/leaning on benchwork will be necessary from time to time.

Trackwork will mostly be within 24 to 30 inches from the layout front edge, but scenery construction will require that extra reach in places.

One section will have a 20' long, eight track freight yard, behind that the double track mainline, behind that a passenger terminal with 4 tracks - 14 tracks requires a minimum depth of 28", without even allowing for passenger platforms or other separating features. Behind the passenger tracks will be a city scene........the 48" depth barely works.........

I'm sure even a "newby" can figure out what his situation might require......

Sheldon

    

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Posted by jjdamnit on Saturday, August 17, 2019 3:18 PM

Hello All,

Mark R.
I'll always remember a comment made by Tony Koester many years ago when asked why he used 3/4" plywood for his road bed. His response was that nobody made 1" plywood.

But "They" do make 1-inch plywood.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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Posted by Marc_Magnus on Saturday, August 17, 2019 3:21 PM

 

I use 3/4 plywood for my N scale roadbed

The layout itself is open grid construction with 3/4 plywood bolted to an iron frame; the layout is divided in numerous modules each has his own iron frame.

This was done to move if necessary the layout.

Yes heavy, but this is a permanent layout, but with two friends we have move all the modules quiet easily and put them in a container for my move in Canada.

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Posted by BATMAN on Saturday, August 17, 2019 3:30 PM

Marc_Magnus
Yes heavy, but this is a permanent layout, but with two friends we have move all the modules quiet easily and put them in a container for my move in Canada.

Welcome Marc!

What part of the Great White North are you moving to? Train Guys are always welcome.Laugh If you end up on the West Coast and need help putting the layout back together let me know.Cowboy

Brent

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Posted by UNCLEBUTCH on Saturday, August 17, 2019 3:43 PM

ATLANTIC CENTRAL
I'm sure even a "newby" can figure out what his situation might require......

But thats my point,they don,t  there for they ask. I feel we should be stating the bare, minimal facts,and not over loading them with info they don't need,didn't ask for. What you plan on doing makes perfect sence,if he [the OP] voiced an interest in a layout such as you plan, he didn't.

 Kinda like telling me how to build a clock,and where to get the parts,because I asked for the time of day.  just MO.

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Posted by ATLANTIC CENTRAL on Saturday, August 17, 2019 3:50 PM

UNCLEBUTCH

 

 
ATLANTIC CENTRAL
I'm sure even a "newby" can figure out what his situation might require......

 

But thats my point,they don,t  there for they ask. I feel we should be stating the bare, minimal facts,and not over loading them with info they don't need,didn't ask for. What you plan on doing makes perfect sence,if he [the OP] voiced an interest in a layout such as you plan, he didn't.

 Kinda like telling me how to build a clock,and where to get the parts,because I asked for the time of day.  just MO.

 

But the OP says his layout plan is 8' x 6-1/2' ? Sounds like an island layout, with pretty deep reach in distances to me? Short of seeing a diagram to the contrary?

Did I miss something?

Sheldon

    

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Posted by carl425 on Saturday, August 17, 2019 3:55 PM

UNCLEBUTCH
What you plan on doing makes perfect sence,if he [the OP] voiced an interest in a layout such as you plan, he didn't.

Well actually, he kinda did.  He said his dimensions were 8ʻ x 6 1/2ʻ, which very well might result in a layout that gets climbed on top of. It'll at least get leaned on pretty firmly.

I have the right to remain silent.  By posting here I have given up that right and accept that anything I say can and will be used as evidence to critique me.

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Posted by jjdamnit on Saturday, August 17, 2019 4:08 PM

Hello All,

I'll throw the proverbial "spanner in the works"...

Many of the responses have been focused on bench work.

You have not specified what method of support you are using. 

To really answer your question of thickness of plywood sub roadbed that information would be helpful.

kenben
...they will be cut up a bit for track elevations etc.

For your elevations are you planning on using the cookie cutter method or are you planning on adding risers on top of the sub roadbed?

Sharing these answers will help folks on this forum better address your specific issues.

Hope this helps.

"Uhh...I didn’t know it was 'impossible' I just made it work...sorry"

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