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How much shrinkage to expect

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Forum topic by one60fourth posted 07-21-2017 01:10 PM 372 views 0 times favorited 11 replies Add to Favorites Watch
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one60fourth

29 posts in 1431 days


07-21-2017 01:10 PM

I’ve built some inset panel cabinet doors (25”H x 20”W x 3/4”) using 2.25 inch wide yellow poplar for the frame and 1/2 inch BB ply for the panel. The wood was purchased milled and kiln dried and I milled it further in my shop. They’ve been sitting flat without a finish on them for a couple of weeks when the humidity has been high (Boston area). I’m going to custom fit them to their face frame openings and am wondering how much shrinkage to expect by the middle of winter when humidity is low. I don’t have a moisture meter. I was going to allow a 1/8 inch reveal between the door and face frame but I’m wondering if that is too much for this season considering the gap will likely be greater come winter. Any thoughts would be appreciated.


11 replies so far

View TheFridge's profile

TheFridge

8333 posts in 1326 days


#1 posted 07-21-2017 01:27 PM

Hardly any expansion contraction with that. You have to worry about a solid panel but not ply.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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TungOil

748 posts in 335 days


#2 posted 07-21-2017 01:33 PM

1/8” all around might be too much. You can estimate the wood movement using the calculator here, but without a moisture meter you would have to guess at the summer and winter MC:

http://www.woodweb.com/cgi-bin/calculators/calc.pl?calculator=shrinkage

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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PPK

870 posts in 649 days


#3 posted 07-21-2017 01:40 PM

Fridge is right. Ply doesn’t move to any significant degree. If that was solid wood, it would move. If you’re staining /dying it, its a good idea to stain the panel before assembly. But not 100% necessary. I’ve done it both ways even on solid panels.

-- Pete

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TungOil

748 posts in 335 days


#4 posted 07-21-2017 01:50 PM

Correct that the center panel won’t move noticeably since it’s plywood, but I believe the OP is concerned about the space between the stiles and the cabinet opening on an inset door, not the center panel. With an inset door that is a legit concern. Using the calculator I linked to above and assuming 10% MC summer, 5% MC winter, 4.5” of yellow poplar will shrink about 3/32”.

If I were making inset doors and fitting them today (~95 deg. and 90% RH here in Philly area) for paint, I’d fit them very tight, closer to heavy 1/32” clearance on the stiles.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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one60fourth

29 posts in 1431 days


#5 posted 07-21-2017 02:04 PM

Thanks for the replies so far. But I’m no really concerned about panel movement as BB ply is very stable. I was really wondering more about the degree to which my 2.25 inch poplar frames would contract in winter from high humidity conditions right now. Another question: Since I used tongue and groove construction (glued) for the frame how can there be any expansion at all? The rails won’t expand along their length right? So the stiles, glued to the rails. can’t move along their width. Beginner questions I know. But this is my first major cabinet project.

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one60fourth

29 posts in 1431 days


#6 posted 07-21-2017 02:22 PM

Sorry TungOil. I made my 2nd post before seeing your 2nd reply. Yes, gap between stiles and cabinet is my concern and I think your moisture guess (12% vs. 5%0 is probably pretty accurate. A heavy 1/32 seems like it would be a challenge in terms of finding a good spacer with that thickness and in terms of calculating the correct distance for my euro hinge hole but I can do a 1/16 with no problem. With 3/32nds expansion that would give me 7/64ths gap on each side in winter which would be fine.

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TungOil

748 posts in 335 days


#7 posted 07-21-2017 02:23 PM

correct, the length of the rails will remain essentially unchanged, only the width of the stiles will move, and it will not move much. That is why the construction technique is used. so your only concern is the 2×2.25 = 4.5” of poplar and how tight you fit the inset door into the face frame. this may help:

http://www.popularwoodworking.com/tricks/how-to-calculate-wood-shrinkage-and-expansion

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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TungOil

748 posts in 335 days


#8 posted 07-21-2017 02:26 PM

don’t over think this- the worst that can happen is the door sticks a bit in the summer. Euro hinges have lots of adjustability in them as well so you could probably adjust it out. If not plane a bit off the offending side, touch it up and you are back in business.

-- The optimist says "the glass is half full". The pessimist says "the glass is half empty". The engineer says "the glass is twice as big as it needs to be"

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one60fourth

29 posts in 1431 days


#9 posted 07-21-2017 02:57 PM

TungOil, you guessed where my mind is on this thing i.e. if it binds in summer I can just rework the door a bit, adjust the hinge side gap with the hinge screws, and apply touch-up paint. Wish me luck as I’m starting my door fitting task right now. I’ve only fitted one practice door so far so and it took me several hours to shim, cut and plane as needed and attach hinges. But it came out perfect.

Thanks to all who replied.

View firefighterontheside's profile

firefighterontheside

16963 posts in 1696 days


#10 posted 07-21-2017 03:13 PM

1/8” is gonna work out fine. You will never have enough shrinkage or expansion in a few inches of poplar to see any measurable difference. I’m assuming you will have finish on all sides of the doors and that you keep the space conditioned. Yes the humidity will be lower inside the house in the winter, but not that much lower than in the summer indoors.

-- Bill M. "People change, walnut doesn't" by Gene.

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one60fourth

29 posts in 1431 days


#11 posted 07-21-2017 06:16 PM

the humidity here (coastal environment) is in the mid-60’s% to high-70’s% year-round. It can dip low in winter on some days but on average is well-above 50% throughout the year. And we don’t have air-conditioning for summer. But like you and TungOil say, 4.5 inches of poplar isn’t going to move all that much.

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