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Allowing for Shrinkage and Swelling

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Forum topic by HorizontalMike posted 06-28-2013 10:01 PM 677 views 1 time favorited 10 replies Add to Favorites Watch
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HorizontalMike

6968 posts in 1667 days


06-28-2013 10:01 PM

Topic tags/keywords: shrinkage swelling species allowing for

OK, we all know this happens and that we should always allow for this to happen in our projects.

BUT how much:
  • per inch of width?
  • per Species of wood?
  • in the deep South?... of far North?

All of the literature says to allow for this, but I am lost as to finding any reference source that tells me that a 9in(or 4in, etc) wide pine board will need xxx fraction of an inch of space for expansion/contraction.

Help me out folks, is there a source I am missing, you know… that one source that eludes me?

-- HorizontalMike -- "Woodpeckers understand..."


10 replies so far

View AandCstyle's profile

AandCstyle

1486 posts in 1010 days


#1 posted 06-28-2013 10:36 PM

Hey, Mike, did your finger have a spasm causing you to post this innumerable times? LOL

I use the Shrinkulator. Is that what you were looking for?

-- Art

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LoydMoore

96 posts in 710 days


#2 posted 06-28-2013 10:55 PM

Shrinking and swelling can be controlled with Viagra.

-- Loyd, San Angelo, TX http:www.moorewoodenboxes.com

View pintodeluxe's profile

pintodeluxe

3570 posts in 1566 days


#3 posted 06-28-2013 11:14 PM

I made a 42” wide table that shrunk 3/8” in total width. Luckily the breadboard ends were built to handle the movement. So that is about 3/32” per foot of width. Species was quartersawn white oak. Flatsawn boards will move / cup even more. Using Art’s shrinkulator link, a 42” table that dried from 10% m.c. initially, to 7% m.c. would shrink 1/4” for qswo, and 1/2” for flatsawn white oak. So it looks like the calculation is pretty close to what I have observed.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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HorizontalMike

6968 posts in 1667 days


#4 posted 06-29-2013 01:11 AM

MY window never refreshes so I DO NOT know what the hell is going on! My apologizes. I do NOT know how long this will continue… Geez,,,

-- HorizontalMike -- "Woodpeckers understand..."

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HorizontalMike

6968 posts in 1667 days


#5 posted 06-29-2013 01:14 AM

That helps Pinto, but I am looking at Pine movement in particular… if tht is possible…

-- HorizontalMike -- "Woodpeckers understand..."

View pintodeluxe's profile

pintodeluxe

3570 posts in 1566 days


#6 posted 06-29-2013 04:33 AM

Looks like about 3/32” shrinkage per foot of width in Eastern White pine. This assumes a shift in m.c. from 10% to 7%. This also assumes flat sawn boards.
A good rule of thumb might be 1/8” per foot of width, just to be on the safe side.

Interesting topic.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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HorizontalMike

6968 posts in 1667 days


#7 posted 06-29-2013 06:48 PM

Pinto,
I guessed and left 1/16” gap on my 7 1/2” door panel. Looks like I may be OK.

-- HorizontalMike -- "Woodpeckers understand..."

View redSLED's profile

redSLED

687 posts in 646 days


#8 posted 06-29-2013 07:04 PM

Wow, a couple of replies from others and myself just disappeared from this thread for no apparent reason.

-- Perfection is the difference between too much and not enough.

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pintodeluxe

3570 posts in 1566 days


#9 posted 07-03-2013 06:39 PM

Here is another wood movement calculator from OSU that offers choices for flatsawn, riftsawn, or quartersawn…

http://owic.oregonstate.edu/wood-shrinkswell-estimator?f=1

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Don W's profile

Don W

15578 posts in 1321 days


#10 posted 07-03-2013 07:00 PM

redSLED. Mike posted this when the site was having issues. There are several different copies of the same post. I have a post the same day did the same thing.

-- Master hand plane hoarder. - http://timetestedtools.com

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