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Shrinkage question

Started by nh-dan, June 24, 2015, 09:50:15 AM

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nh-dan

Hello I'm new here. I'm going to be cutting some white pine beams for my post and beam camp. I plan on stick and stacking it outside on a cement pad with a piece of rubber roof covering it. How much should I expect the beams to shrink? If I'm looking for an 8x8" finished beam should I over cut them a bit?
Thanks
Dan
woodmizer lt20D, NewHolland TC23D

ely

yes you will need to over cut them, I am not certain exactly how much though. it seems in my experience that none of my pine dries and shrinks the same... so if you have to be exact on your measurements you may need to cut big and then resaw after drying.

beenthere

nh-dan
Welcome to the Forestry Forum.

E. white pine is low for shrinkage. The values expected for the radial and tangential, as well as volumetric for many species are found in a table in this publication.

http://www.albertforestproducts.com/shrink.htm
south central Wisconsin
It may be that my sole purpose in life is simply to serve as a warning to others

red oaks lumber

welcome
what i like to do is saw an 1" over both ways,let them dry and then resaw them to my final size.not only do you have a consistant size but,there are clean and bright again.yes its more work but having a nice final product trumps any added labor :)
the experts think i do things wrong
over 18 million b.f. processed and 7341 happy customers i disagree

nh-dan

Thanks guys I think I'll over saw and cut twice
Dan
woodmizer lt20D, NewHolland TC23D

Magicman

Welcome to the Forestry Forum, nh-dan.   
Knothole Sawmill, LLC     '98 Wood-Mizer LT40SuperHydraulic   WM Million BF Club Member   WM Pro Sawyer Network

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GeneWengert-WoodDoc

Eastern white pine shrinks 2.1% when going from green to 0% MC in the radial direction (this is perpendicular to the growth rings, or this is the thickness of flat sawn lumber or the width of quartersawn), and 6.1% in the tangential direction (width of flat sawn and thickness of quartersawn).  This data is from small pieces.  The value is less for larger pieces.  Further, you will not be going to 0% MC, but in your air drying will get the large pieces to around 15% MC or a bit higher.  That means you will get half of the maximum shrinkage.

So, expect 1% shrinkage radially (perpendicular to the rings) and 2.5 to 3% tangentially.  To be safe, maybe go with 3% in both directions, which for an 8x8 would be 1/4".  This is for shrinkage.  You may want more for roughness if you plane them and also have an allowance for warp.

Note that EWP will not shrink lengthwise, except in a rare case.
Gene - Author of articles in Sawmill & Woodlot and books: Drying Hardwood Lumber; VA Tech Solar Kiln; Sawing Edging & Trimming Hardwood Lumber. And more

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