warping problem

[Judy Hunter]

What am I doing wrong.  I love to do boxes ...But the lids warp asfter a while. How do I prvent or correct this??
This box is cut from 1/4 inch baltic birch it is about 7 inches square.  the right front corner is raised. 
Sure appreciate any suggestions. 

[Bill P]

Warping is common with birch plywood, usually the twist-type of warping. Usually caused by the change in moisture content after manufacturing. Plywood almost always has a low moisture content because of the heat used in drying and gluing.

Also, instead of cutting parallel to the bark, which minimizes warp, veneer is cut parallel to the pith. This means that there is "slope of grain" which means that the wood is moving in all three directions, instead of two, as the MC changes.

The lid is "floating" since it's not attached on 3 or 4 sides like the rest of the box.  I believe I read somewhere that if you're going to make a box out of plywood, to only do the bottoms and sides, and cut the lid of solid wood.

Bill

[dgman]

Judy, I did the same box done with Spanish Ceder. the Spanish Ceder is prone to wrapping anyway so I made sure that the stock was stacked and stickered when not working on it. One important thing I did to help with the warping was to tape both sides of the wood to keep the moisture level equal on both sides. I glued the pattern to the top of the wood, then clear packing tape, then on the other side, I glued plane paper and then tape. With Thin woods it is important to do the same thing on both sides, so if you use mineral spirits to clean off glue residue on one side, do the other side too.
When I mounted the hinges to the box, the top did no set level, like yours. To fix this, I shimmed the hinge on the opposite side of the warp with a piece of paper folded in half. That cured the problem!

[dunk]

Judy, Dan and the fat kid nailed it...   Great advice fellas.

[dgman]

Judy, Dan and the fat kid nailed it...   Great advice fellas.

LOL!!!

[Bill P]

ROTFL!!   

[lwilli]

Dan, you're a wealth of information. I sure picked up some valuable information after reading your post.

Louis

[Marcellarius]

next to all the true words that have been said I would trough in my 2c

what might be important to look at is how the wood is cut.
so, what part of the lumber does it come and how is it sawn?
there are three ways of sawing: tangential sawn(plain), riftsawn and quartersawn.

The wood you want (with the least warping) is called quarter sawed. 
this is more expensive than plain sawn wood.(rift sawn isn't used much)

http://en.wikipedia.org/wiki/Quarter_sawing

in the woodwrightshop, somewhere in the middle of the video, he explains this to.

http://www.pbs.org/woodwrightsshop/video/2900/2906.html

I guess you can't prevent warping 100% but the right wood will help us.

[Judy Hunter]

Thanks guys...... guess I will think about using non plywood type wood for the topss from now on.

[Marcellarius]

maybe you could glue a 1/4" or 1/8" part in the opposite direction (on the inside) and make your own plywood.
this will prevent from warping to.

[Rapid Roger]

I have made allot of wooden boxes but the way I do it won't work on a fretwork box like you show.
I usually build a solid wood box and glue all six sides so that there is NOT a separate top and then cut the top/lid off on my table saw leaving any where from 1/2" to 1" lip all around the top for hinges or a recessed fitting lid. They do not warp that way. This method also helps with grain matching on a highly figured, solid wood box.
In order to do a fret work box that way, you will have to leave a blank area all around the box (about 1/2" or more) down from the top. for the cut to be made there.
It may not always be a workable solution but, if you can do it that way, it will keep the top from warping.
Hope this makes sense.

Rog

[Judy Hunter]

Yes Roger that does make sense.  I will work on trying that.

[BilltheDiver]

I have made boxes and installed rare earth magnets in two corners of the top which exert constant pull to counteract any tendency to warp.  I cut a mantle clock out of maple which is 3 inches thick, and the front is hinged.  The front wanted to warp, so I clamped it to the main body for a few days and then used magnets as the closure.  Never had the problem again.

[jimbo]

Judy 1/4 " is very thin wood I use no less that 10mm and normally 11to 12mm and have had no problems, I use this thickness for the whole box, it is better for gluing as well
Jimbo

[julief]

Roger, that is the method my Dad used in 1967 to make toy boxes for my sinblings and I.  All three of us still have them and they are still sturdy furniture.