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Interesting shrinkage (?) behavior in Douglas fir

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Forum topic by JJohnston posted 01-30-2012 12:31 AM 1179 views 0 times favorited 12 replies Add to Favorites Watch
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JJohnston

1577 posts in 1943 days


01-30-2012 12:31 AM

This piece came from a dime-a-dozen DF 2×6x8’ from HD. It’s had just a bit planed off the surfaces, so it’s nearly the full 1.5” thick, and about 2” wide. You can see from the grain it’s almost perfectly flat sawn (and check out how tight the grain is – I counted about 70 rings in that 1.5”).

The odd thing is the hourglass shape. It’s not an illusion, or a camera effect. I ripped this with a table saw about a week ago, and the edges were straight. In the second shot, I’m holding a piece of MDF against it with the sun pointing right at the end to eliminate shadows, and you can see the gap. Anybody ever see this before?

-- "Sorry I'm late. Somebody tampered with my brakes." "You should have been early, then."


12 replies so far

View Nighthawk's profile

Nighthawk

438 posts in 1009 days


#1 posted 01-30-2012 01:36 AM

Have see something similar on some Manuka once….

wood not fully dried ???

-- Rome wasn't built in a day... but I wasn't on that job? ... http://www.wackywoodworks.co.nz

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poopiekat

3626 posts in 2386 days


#2 posted 01-30-2012 01:50 AM

Isn’t this stuff kiln-dried after it’s dimensioned?

-- Einstein: "The intuitive mind is a sacred gift, and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift." I'm Poopiekat!!

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JJohnston

1577 posts in 1943 days


#3 posted 01-30-2012 02:56 AM

I’m sure it is. This piece came from near the center, so it may not have been as dry as the edges. What you don’t see is that the grain is also really straight, so this hourglassing is the only warpage happening.

-- "Sorry I'm late. Somebody tampered with my brakes." "You should have been early, then."

View ksSlim's profile

ksSlim

984 posts in 1542 days


#4 posted 01-30-2012 06:36 AM

Grown on the northeast side of a slope. Has experienced a lot of twisting and flexing (probably due to wind) before harvest. Usually after moisture is down to less than 8-10 % the lumber can then be milled to the desired shape (Square edges?)

-- Sawdust and shavings are therapeutic

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QuangFromCalgary

25 posts in 1650 days


#5 posted 01-30-2012 08:09 PM

Are you sure your table saw blade is straight?
Just kidding! Can’t help…:)

View bondogaposis's profile

bondogaposis

2524 posts in 1003 days


#6 posted 01-30-2012 08:32 PM

It’s because the outside of the board was drier than the inside, and once you opened it up and exposed the inner surfaces they started drying. Beautiful piece of old growth df by the way. This piece of wood needs more time to adjust to the ambient humidity.

-- Bondo Gaposis

View mrpedal's profile

mrpedal

30 posts in 1190 days


#7 posted 01-30-2012 10:56 PM

Was considering making some interior door frames out of CVG doug fir, mainly because I read somewhere it didn’t move a lot, and it’s harder than some hardwoods, and takes paint nicely.

Is the movement in the picture normal? Is the lesson here to mill it oversize, and let it rest for (fill in the blank) days/months/don’tsayyears ?

View Nomad62's profile

Nomad62

709 posts in 1610 days


#8 posted 01-31-2012 12:12 AM

Believe it or not, the vast majority of df you get in that manner is green as the day is long. They cut and mill it, then run it thru a heater to kill any bugs, dip it in a bug/mold killer, then stack it and sell it. The kiln dried 2×4’s there are white wood, usually poplar. The reason you don’t see that more often is because it is extremely rare to see such a tight grain in fir; there is enough structure in all them lines to hold it from cupping, the “normal” type of movement associated with flat sawn woods. I know a lot of sash and frame makers that would happily pay $2.50 a board foot for that wood.

-- Power tools put us ahead of the monkeys

View superstretch's profile

superstretch

1504 posts in 1345 days


#9 posted 02-02-2012 06:40 PM

Was it in the pool?

-- Dan, Rochester, NY

View JJohnston's profile

JJohnston

1577 posts in 1943 days


#10 posted 02-03-2012 03:14 PM

The pool? I don’t think so – it was in HD, then the back of my truck, then my garage, where it’s been since.

-- "Sorry I'm late. Somebody tampered with my brakes." "You should have been early, then."

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superstretch

1504 posts in 1345 days


#11 posted 02-03-2012 04:37 PM

Heh.. Seinfeld reference..

-- Dan, Rochester, NY

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Bertha

12951 posts in 1345 days


#12 posted 02-03-2012 05:00 PM

^shrinkage! I think it probably has most to do with HD. There’s no telling how that stuff was handled. It looks like a nice piece of wood, though. I haven’t seen any that nice in my local store. Perhaps I should have another look:)

-- My dad and I built a 65 chev pick up.I killed trannys in that thing for some reason-Hog

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