Stupid Question - lumber dimensions

[spokeshave]

I apologize if this has been addressed before. I am going to be milling some White Pine for framing lumber for building a cottage. My preference is to mill it to commercially available nominal dimensions, i.e. 1-1/2" by 3-1/2" rather than 2" x 4". I want to do it this way for two reasons - if I run short on milled lumber, I can still use the lumber yard stuff; and door and window jambs will be standard thickness.  I know I can expect some shrinkage as it dries. It will be dried in a solar kiln. So, what dimensions should I mill the lumber to? Can the question even be answered?

Thanks.

Tim

[Bibbyman]

One way we've handled the problem was to mill some 2X stuff to 1-5/8" thk. and as wide as practical.  Then we stick and air dry.  When it comes time to use it,  we pull it out and re-saw it to the width we want - i.e - 3-1/2, 5-1/2 etc.  Thus everything was "pre-shrunk".

Most studs and floor joist, etc,  a little off on the thickness don't matter but the width has to be right and true.  

Where you are dealing with a place where the thickness needs to be pretty well right on - like a window header -,  then we ran them through a planer - just to get the thickness down to a consistant 1-1/2".

The customer was happy,  we were paid so we were happy. 8)

[ADfields]

You could test cut some small chunks and dry it in your home oven.   This would give you a % of shrink in both ways to work your math from that is for your trees and local.   A 2x4 cut to an inch long will dry in a couple hours with the double end grain exposed and get you right close to what you want. ;)   You will still have cupping in top gran lumber witch is the best reason to run them through a planer.  :-/   But for many many years nobody planed framing lumber at all. ;D
Andy

[ARKANSAWYER]

  I mill SYP to 1 5/8 x 3 5/8 and it works out fine.  You can run it through a plainer in a few weeks and it will just touch at 1 1/2.  In most things I build a 1/4 inch differance would not matter. :D  In things wider then 6 inches I cut to full width and then re-size to width to take out any bowing before using but they all are 1 5/8 thick.
ARKANSAWYER

[EZ]

I sawed some white pine 1x 12, air dry, and solar kiln and it dried at 3/4 x 113/4. Where the knots are it measured 7/8's.
EZ

[FeltzE]

EZ,

EWP has a 6.1% tangental shrinkage rate. (around the ring) and a 2.1 % Radial shrinkage rate . I don't know what the shrinkage rate is for the length of the lumber but I believe it's in the relm of .3% or practically nill.

The reason that your lumber is shrinking differently is that the grain along the lumber is shrinking more tangentally in the flat sawn lumber less out the grain of the knott.

This will also take a beautifully straight piece of lumber and cause the edge to pull in towards a large knott as it dries. People think you did a poor job of sawing but it may be a natural result of shrinkage.

An easy example is to take a 2x4 with a large knot partially sawn on one side and let it dry, the result will be a 2x4 with a crook towards the knots side.

Eric

[FeltzE]

If my math is correct to end up with a 3.5inch 2x4 you will have to cut a nomimal  .21" over your finish dimension assuming perfect flat sawn all tangental shrinkage. Cut the lumber 1/4" over and plane or resaw to the final width after drying.

Eric

[OneWithWood]

I started out cutting my dimension lumber at the true 2" x 4", etc.  I quickly discovered that all the building tools, nail guns, joist hangers and other paraphenilia are all sized for the commercial finished sizes, duh!
Now I am sawing similar to what Arky posted.  I find I can use the inch scale on the mill to drop 1 3/4 inches and I end up with 1 5/8 lumber.  Makes figuring the drop easy.