Wood Movement Calculator

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Blog entry by Karson posted 10-21-2007 07:37 PM 9233 reads 1 time favorited 3 comments Add to Favorites Watch

There has been a lot of discussion on this site and probably others about wood movement.

How much does wood move

What about quartersawn lumber

Does flat sawn lumber move more than Quarter Sawn

The US Government has created a Wood Handbook that has lots of tables but how does that become useful?

I took the tables and created an Excel Spreadsheet to calculate the wood movement. But, I came across a wood Movement Calculator that you can download and run on your computer. This program works with Windows computers. It seems that the calculator has disappeared from ther web Here is another link. I can provide a copy of mine since its shareware I assume the author won’t mind. Well I found it again here

There are two fields that might be a little hard to figure out what that it means. At least they were to me, this 65 Yr old retired programmer. A long time since I worked math. The terms are Initial Radial Length and Init Tangential length

Here is a copy from the web page.

The amount that wood expands or shrinks varies depending on the species of wood and the direction relative to the grain being measured. All species expand/shrink very little in the longitudinal direction (“along the grain” or in the direction of the axis of the tree truck). Longitudinal shrinkage is so slight that it can usually be ignored in wood working. Shrinkage in the radial direction (perpendicular to the growth rings, or along the radius from the center of the tree toward the bark) is more pronounced. Typically, most wood species will shrink around 3% to 6% of their original length in the radial direction as the wood is dried from it’s green or saturated state to “oven dry”. Shrinkage in the tangential direction (tangent to the growth rings) is typically 1.5 to nearly 2 times the radial shrinkage.

So as I read this Radial could be on a truley quartersawn board the radial length would be the width of the board and the Tangential length would be the thickness. If it was a flatsawn board then radial would be the thickness and Tangential would be the width.

Good luck on using this tool on working wood.

I didn’t post this as a response, because I wanted to be able to find it later.

-- I've been blessed with a father who liked to tinker in wood, and a wife who lets me tinker in wood. Appomattox Virginia [email protected]

3 comments so far

View CedarFreakCarl's profile


594 posts in 4508 days

#1 posted 10-22-2007 12:40 AM

Thanks Karson….you can’t have too much information. This topic is actually some something I’ve been wondering about as I’ve been working on some bread boards for a coffee table. Thanks again for posting.

-- Carl Rast, Pelion, SC

View CedarFreakCarl's profile


594 posts in 4508 days

#2 posted 10-22-2007 12:41 AM

Thanks again Karson….as I had a spelling error on the previous post and accidently posted this one trying to correct it and can’t get rid of it….lol.

-- Carl Rast, Pelion, SC

View Steffen's profile


326 posts in 4490 days

#3 posted 10-30-2007 05:42 PM

thanks karson….

-- Steffen - Kirkland, WA

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