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Forum topic by BalsaWood posted 05-08-2017 05:29 PM 580 views 0 times favorited 9 replies Add to Favorites Watch
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BalsaWood

35 posts in 997 days


05-08-2017 05:29 PM

I made a solid cherry night stand using dados. I also added in a solid cherry back to it which might be a problem. The solid backing is a glue up made using 1/4 thick cherry and is about 22” wide and 2 feet high. I installed the solid backing into a rabbet that runs across the shelves and sides using glue and 23 gauge pins. This was all done during the winter in the basement.

In the past I used to use plywood for any kind of backing and wasn’t worried about movement. I completely overlooked it this time. Question is what might happen to this when summer comes or what might happen a few years down the line?

Also, for the future, what would be the best way to attach a glued up solid backing to a bookcase?


9 replies so far

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johnstoneb

2641 posts in 2011 days


#1 posted 05-08-2017 05:36 PM

With that size I doubt that anything will happen. It’s on the back so if it does split nobody will see it. 1/4” back will split long before any other components do.

-- Bruce, Boise, ID

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Rich

1984 posts in 428 days


#2 posted 05-08-2017 06:38 PM

Since you built it in the winter when it’s dry, it’s pretty certain the wood will be expanding in the more humid months that follow. I’m not sure how much clearance you left though, so it’s hard to say if it will be a problem.

If you don’t want to use plywood, then shiplapped boards, not butted tightly, will allow movement without putting any strain on the case.

-- No matter how much you push the envelope, it'll still be stationery.

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BalsaWood

35 posts in 997 days


#3 posted 05-08-2017 08:01 PM

What about attaching solid backing using a long cleat screwed to shelves on the back side. The solid backing would be compressed and held between the cleat and back of the edge of the shelf. To account for movement, I could route a slots through the backing where screws will be. Would something like that work?

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papadan

3584 posts in 3207 days


#4 posted 05-08-2017 08:08 PM

Your home is heated in the winter and cooled in the summer, Right? the air quality wont be much different any time of year, don’t worry about it.

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Rick_M

10640 posts in 2219 days


#5 posted 05-08-2017 08:24 PM

It’s going to depend on where you live. In the desert, no big deal. In a humid climate there is a lot of potential for problems. Wood movement is hydraulic and therefore very powerful. The nails are fine, but if you glued it all the way around and the panel expands, something else has to move with it or the panel will bow. Now if your house is conditioned evenly all year round, there may not be a problem. My father in law made the same mistake on a headboard and it twisted one of the posts. I cut it apart and used it for scrap.

-- http://thewoodknack.blogspot.com/

View JBrow's profile

JBrow

1274 posts in 759 days


#6 posted 05-08-2017 10:14 PM

BalsaWood,

It is difficult to say what might happen as time goes by. If the back absorbs enough moisture, the back could try to bow as the back expands across it width. With shelves holding the back in place, the stress from the expansion could result in some cracking in the back. I doubt that a ¼” thick back would exert sufficient force to loosen some joinery.

If the back loses enough moisture, as the back tries to shrink, the back could crack.

Short of major surgery, ensuring several coats of a film finish on both faces of the back could retard enough moisture from entering or leaving the back so that no problems would ever occur.

If the shelves were attached to the back with screws through slots cut perpendicular to the grain direction in the back and an expansion/contraction gap provided where the back meets the sides, the back would be free to move which, I would think, would avoid any problems.

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BalsaWood

35 posts in 997 days


#7 posted 05-08-2017 10:14 PM

I did glue it all the way around. Hopefully it doesn’t cause the dado joints to loosen up.

View gargey's profile

gargey

862 posts in 614 days


#8 posted 05-08-2017 10:35 PM


Short of major surgery, ensuring several coats of a film finish on both faces of the back could retard enough moisture from entering or leaving the back so that no problems would ever occur.
- JBrow

Finishes can slow the rate at which moisture enters/leaves, but will not prevent full acclimation from taking place (maybe in 2 days instead of 1, for instance, in a serious weather change). The total amount of shrinkage and expansion will be materially the same.

View Kelly's profile

Kelly

1821 posts in 2783 days


#9 posted 05-08-2017 11:58 PM

How about the elephant in the room?

I’ve heard even pro’s claim the interior of dressers and such do not need to be finished. This is a bit like the little girl asking mom why she cut off the ends of the ham. Mom said she learned it from grandma and to ask her why. Grandma said it was because the ham wouldn’t fit in the pan. So too it is with the interior of fine woodwork – the interiors were not finished to save time and money.

Think about it. We laminate the underside of laminated counter tops for a reason. Too, if a dresser were totally finished, inside and out, the rate it would take on or lose moisture would be greatly reduced. As such, the chances of it taking humidity hits would be minimized.

On another matter, does anyone know if a door sticks because it took on moisture, or because the frame, with only a little paint on some trim changed?

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