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Question on "new" plywood sizing...........

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  • Member since
    December 2007
  • 69 posts
Posted by Bighurt on Thursday, January 22, 2009 8:55 PM

  The big box stores BB has always been of substantially lower quality and at a higher price than the product offered by actual lumber dealers.  I get my BB from a cabinet shop that stocks the stuff locally.  I also get my Oak, Maple, Cherry or walnut 3/4 sawn from the same place. 

 Due to the additional glue factor of the multiple plys it is of higher weight than traditional ply.  However its additional strength means you can reduce the thickness without giving up strength, reducing the weight.  The thin factor also requires a better joint. 

Combined with an Extruded Polysterene surface you could build the open grid with 1/8 lauan and achieve a very strong structure.  Infact the O scale Pioneer valley featured in MR in 93' was built in the same fashion.  I would use 1/8" BB if I recreated the structure again because ply tends to be an inert product.

If I wasn't tossed between ply sub roadbed and foam I would be started by now....

  • Member since
    February 2004
  • 394 posts
Posted by ham99 on Thursday, January 22, 2009 5:55 PM

The Baltic Birch is great.  My last layout was built of it.  I'm not using it this time, because it is heavy and harder to cut.  Track nails bend too often in it.  But an elephant could walk on it, and I never found a void in cutting it.  After carrying the modules up the basement steps and to the truck to go to the landfill, I would appreciate a lighter plywood.  But I was not impressed with the plywood at Home Depot.  It was warped, rough, and $4 a sheet higher than a much better A/C ply at a local lumber yard.  We don't have a Lowe's to compare. 

  • Member since
    December 2007
  • 69 posts
Posted by Bighurt on Thursday, January 22, 2009 4:48 PM

 Nothing new just typically ignored.  Most plys are cut to 1/8" nominal so typical 1/2" has 4 plys.  The plys had strength, so the more the better, kinda like Vultron...

 The older cheaper ply had larger fill ply, in the middle, so could see a 3 ply 1/2"

 Anyways since it was already brought up the Russian and Finnish Baltic Birth plys are probably the best out there as far as cost and quality.  And most US distributors do the conversion from MM to SI.  The real nice thing about those products are the number of plys, BB plys are usually 2 mm so you'll see 5-7 plys in whats about a 1/2" thick board.  Or for those working with larger 3/4", 10-13.  Another plus is the material is usually 5' x 5' rather than 4' x 8'.  Those that build cabinets get more yield where as the MRR gets more curve for each cut.

 The only down side is cost, I've seen it go for $1.62 - $3 a sq foot, CDX 3/4 ply is about $.68 and 1/2" OSB  $.21 to give some estimates. 

My next layout will be BB ply constructed, but I favor an all ply construction.  

  • Member since
    July 2004
  • From: northern nj
  • 2,477 posts
Posted by lvanhen on Thursday, January 22, 2009 3:37 PM

This is nothing new.  For many years lumber/plywood has been sold in "nominal" sizes.  Almost all plywood is 1/32" actual size under the "nominal" size.  2x lumber, normally used for framing etc, is 1/2" under up to 6" nominal, and 3/4" under for 8" & up - i.e. a 2x4 is actually 1 1/2" x 3 1/2", a 2x8 is 1 1/2" x 7 1/4".  1x lumber, usually used for shelves & light construction, is 3/4" thick, widths the same aas 2x lumber.  The lumber is actually cut larger, but shrinks when dried.  The other thing to watch out for in plywood is metric sizes - some nice birch plywood is imported from Russia, and is measured in mm (don't ask me for conversion "!!)  Hope this helps Smile

Lou V H Photo by John
  • Member since
    September 2003
  • From: Southeast Texas
  • 5,447 posts
Question on "new" plywood sizing...........
Posted by mobilman44 on Thursday, January 22, 2009 3:02 PM

Hi!

Just got back from Lowes & Home Depot scouting out plywood for my new layout.  The previous one used 1/2 inch ply (looks like 3 plies) when it was built in the early 1990s.

Now, at least in the above stores, plywood is measured in 32nds of an inch, with 15 (0r 17 - I forgot) 32nds being the closest to 1/2 inch, and it has 4 plies.

Could you explain what brought about the change, and what it means?

Thanks,

Mobilman44 

ENJOY  !

 

Mobilman44

 

Living in southeast Texas, formerly modeling the "postwar" Santa Fe and Illinois Central 

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