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Allowing for Shrinkage and Swelling

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Forum topic by HorizontalMike posted 06-28-2013 10:06 PM 826 views 0 times favorited 10 replies Add to Favorites Watch
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HorizontalMike

6938 posts in 1568 days


06-28-2013 10:06 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 Don W's profile

Don W

15029 posts in 1221 days


#1 posted 06-28-2013 11:07 PM

I think your submit button got stuck!

try this link http://www.woodworkerssource.com/wood_movement.php

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

View Randy_ATX's profile

Randy_ATX

676 posts in 1096 days


#2 posted 06-28-2013 11:11 PM

i was thinking that too.

-- Randy -- Austin, TX by way of Northwest (Woodville), OH

View HorizontalMike's profile

HorizontalMike

6938 posts in 1568 days


#3 posted 06-29-2013 01:19 AM

Dag nam it! go with the one with more posts! Sorry!

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

View Bernie's profile

Bernie

414 posts in 1491 days


#4 posted 06-29-2013 03:11 AM

Mike – I own a Freud raised panel door set and they provide a formula with the set to help determine the size of the lumber. I’ll try to spell it out here…

Stiles are the easiest – they are the length of your doors – always

Rails are (the width of your doors) – (minus the w of your both stiles) + the length of both tongue

Let’s assume your building a 3/4” X 12 X 18 door. In this case, the width of our stiles and rails will be 2” We know to cut the stiles at 18” Our rails will be 12 – 4 + 7/8 = 8 7/8

Now to the panel formula. The length is the height of your door – (minus) the width of your stiles + 7/8 – (minus) 1/16 18 -4 +7/8 -1/16 = 14” 13/16th

The panel width is the width of your door – (minus) the w of the stiles = 7/8 – (minus) 1/8 12 -4 +7/8 – 1/8 = 8 /4

The only thing I do differently is I – (minus) 3/8” on the width of the panel rather then 1/8 because I add space balls inside the grooves of the stiles. The space balls are tiny little rubber balls placed into the grooves at assembly time and they prevent rattle.

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

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firefighterontheside

4298 posts in 510 days


#5 posted 06-29-2013 03:20 AM

I was worried bout that when i was building a big table and wanted to know how much expansion to allow for. I found some tables having to do with different species of woods. Then I looked down at my cypress floor. According to the table I was looking at my floor was going to expand out into the middle of my yard at some point. In 13 years that has not happened yet. So then I just concerned myself with the shrinkage that might happen and not expansion.

-- Bill M. I love my job as a firefighter, but nothing gives me the satisfaction of running my hand over a project that I have built and just finished sanding.

View Loren's profile (online now)

Loren

7554 posts in 2301 days


#6 posted 06-29-2013 03:41 AM

This free book from US Forest Service has a lot of useful
information in it.

http://www.fpl.fs.fed.us/products/publications/several_pubs.php?grouping_id=100&header_id=p

As a rule of thumb I allow for 1/4” per 12” width in
the kiln dried hardwoods I buy. If you put wood
in a house with central heating in a place where it
gets really cold, like the Northeast, it is going to shrink
in the winter… I dunno, maybe get down to 4%
moisture content.

My climate is reasonably forgiving as it doesn’t get
really cold here or especially humid for long stretches.

Guitars made in arid Spain may require special treatment
in a humid climate like the Southeast USA. The top
will expand, raising the bridge height too much. A
top glued on a too humid day may shrink and crack,
which is a much worse situation as once a guitar top
goes flat it can’t do anything else if it gets any drier.

-- http://lawoodworking.com

View HorizontalMike's profile

HorizontalMike

6938 posts in 1568 days


#7 posted 06-29-2013 07:05 PM

Thanks guys for the information. Sorry about the rampant multi-post. Software or isp glitch I suppose…

I hate this getting old stuff. I got so wrapped up in building this old Amish cabinet that I totally fogot about using Space Balls. BTW, I have used them on two previous projects. ..Doah!

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

View Bernie's profile

Bernie

414 posts in 1491 days


#8 posted 06-30-2013 02:45 AM

Don’t worry about it Mike – As we all get old, we all forget to zip up when were done. It will get worse and we will know this when we forget to zip down before we start.

-- Bernie: It never gets hot or cold in New Hampshire, just seasonal!

View Loren's profile (online now)

Loren

7554 posts in 2301 days


#9 posted 06-30-2013 07:05 AM

I have used space balls but I don’t usually. I put a nail
in the center of the panel, top and bottom.

-- http://lawoodworking.com

View robdem's profile

robdem

325 posts in 1260 days


#10 posted 06-30-2013 12:03 PM

Mike was looking thru lee valley catalog yesterday the have a guide in there for what you are looking for .It has 73 species of domestic and imported woods on it and give ranges from 30% to 0% and only 9.50 .

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