Gluing a solid wood cap on a box

[Clarence Miller]

What is the maximum size that you would glue a "cap" on a box? Can I safely get by with 6x6x1/2? Doing an experiment on one now. Built a 6 x 6 box with lock miter joints out if some scrap walnut and then glued a cap on with titebond 3.
Last night I put a wet rag on it and let it sit all night to see if it would cup. It didn't. So now I turned it over and poured water in until it was a 1/4" or so deep. I was pleased to see it was water tight but am wondering if it will stay that way. I post results tomorrow after I check it.
So what do you think I'll have tomorrow morning? A cracked cap, cracked sides, or will it be just fine?

[Clarence Miller]

Still water tight. Dumped the water out and will check for damage after it dries.

[Mike Henderson]

In my experience, a lot depends on the wood. For example, quarter sawn wood doesn't expand and contract as much as plain sawn wood. And I don't know why, but it seems to me that air dried wood expands and contracts more than kiln dried wood. The species probably makes a difference, also.

I've made boxes with a 12x8 top and not had any real problems. I leave 3/4 inch when I cut the top off the box.

Mike

[But I'm in California which doesn't have extreme swings of temperature and humidity. Occasionally we'll have what's called a "Santa Ana" wind which is very dry and the humidity falls to the bottom.]

[Richard Coers]

I'm certain the cap won't be cracked because it will expand. Cracking of the cap will happen in the winter as it contracts. From winter to summer I would expect 1/16" movement on a 6' wide flat sawn walnut board. That leaves broken glue joints, glue creep with the cap no longer flush, or the lid bowing from the expanded cap for this test. But as mentioned, if it's rift, quarter sawn, or just not too near the tree pith, you might get by. You might also not have an issue if you have seen some warmth and humid conditions this spring. The maximum movement is dependent on climate differences where you live, and the full seasonal swing from winter to summer.

[Mel Fulks]

I don't think it will fail. Especially if it's kiln dried.

[Andy D Jones]

I'm not sure that overnight, even soaking in water, is going to be a definitive test. You are essentially reversing the air-drying process, which often takes weeks or longer, not hours or days. The concentration of the moisture in the air (or lack of air in the water!) will not make that much difference in the moisture migration below the surface of the wood.

That said, my father capped the end of a flat-sawn walnut box mantel ~10" wide, with solid walnut end caps. It was still gorgeously intact when the house was sold some 24 years later. However, the 4/4 rough walnut had air dried in an attic for at least 15 years before my father liberated its beauty into the mantel.

-- Andy - Arlington TX

[David Utterback]

If you want to try low humidity, you could stick in the oven for an hour or two at very low setting.

[David Utterback]

What is the maximum size that you would glue a "cap" on a box? Can I safely get by with 6x6x1/2? Doing an experiment on one now. Built a 6 x 6 box with lock miter joints out if some scrap walnut and then glued a cap on with titebond 3.
Last night I put a wet rag on it and let it sit all night to see if it would cup. It didn't. So now I turned it over and poured water in until it was a 1/4" or so deep. I was pleased to see it was water tight but am wondering if it will stay that way. I post results tomorrow after I check it.
So what do you think I'll have tomorrow morning? A cracked cap, cracked sides, or will it be just fine?

I love your Churchill quote. Growing up around farm animals, it made me chuckle. Thanks!

[Marc Jeske]

There was a long thread about a very similar situation a while back... year or more ?

It was all about exp / contraction issues, R Bruce Hoadley kinda stuff... I think I recall quartersawn was overall best, logically so.

Possibly advanced search could help.

Marc

[al ladd]

The best way to do this is to make a plywood top with about 5/64" thick veneer on top. Then rabbet top so only the veneer is exposed. I often make many boxes this way. Nice clean look, no movement worries. http://www.alladd.com/custom-boxes/inlay-boxes-2/index.html 5th thumbnail for an example. 6 inches is marginal with solid wood, and depends on wood's physical traits, which can generally be learned through wood movement tables, but wood can be idiosyncratic when not straight grained, and upon the yearly extremes of high-low equilibrium moisture content it will experience.

[Charles Lent]

I did that on a box of similar size made of red oak, and 3 months later the corners of the top had cracked loose from the box sides. The top didn't come off, but the resulting cracks and appearance caused it to become firewood. When building boxes from Baltic Birch plywood and gluing the plywood top and bottoms direct to the sides I have never had a failure. Solid wood does expand and contract with changes in moisture content, so it's best to make a floating panel for the tops and bottoms of boxes, but plywood tops and bottoms do remain quite stable with changes in moisture content.

Charley

[Mike Henderson]

The best way to do this is to make a plywood top with about 5/64" thick veneer on top. Then rabbet top so only the veneer is exposed. I often make many boxes this way. Nice clean look, no movement worries. http://www.alladd.com/custom-boxes/inlay-boxes-2/index.html 5th thumbnail for an example. 6 inches is marginal with solid wood, and depends on wood's physical traits, which can generally be learned through wood movement tables, but wood can be idiosyncratic when not straight grained, and upon the yearly extremes of high-low equilibrium moisture content it will experience.

That's some beautiful work, Al.

Mike

[Rege Sullivan]

If you are a fan of Matthias Wandel look at some of his videos on draws/boxes or storage bins. He suggests gluing all but the largest boxes. He says he's never had a failure with that method. Myself, I've glued tops and bottoms of many and never had a problem but if it is something over 10 inches long or wide that is of furniture or heirloom quality I stick with more traditional methods.

[Clarence Miller]

Checked out your site, beautiful work.

[Clarence Miller]

Not wanting to risk my kitchen privileges yet I opted for another round of tests. I live in NW Iowa where we get to experience all 4 seasons in the space of a week at this time of the year. This past weekend was cool enough to freeze and sleet, this afternoon was a balmy 56°. It will be in the 70s by the end of the week and 80s next week with plenty of rain, sun, and drying winds to roll through the month. I put it on the picnic table and will check it daily on my walk to the truck to see if the joint fails. I realize the sample size is too small to be called a real experiment with actionable data but I'm curious how long the joints will hold together when exposed to elements that an indoor box will probably never have to endure.


In the long run I will probably go with a floating panel.

[Charles Lent]

You are mostly checking it in wet and semi dry conditions. Put it in the oven and set the temperature as low as it will go, probably about 200 deg for several hours and see what happens. It's the cold and very dry Winters here that seem to shrink and loosen joints in wood furniture. Baking it isn't the same, but will dry out the wood considerably, and you should see some shrinking. A month in the freezer at 0 degrees or below would dry it out even more.

My boxes, posted in the photos above, are completely made from Baltic Birch plywood, which is very stable in both directions as it's moisture content varies. That is the only reason why the tops and bottoms of these boxes don't break free as the moisture content in the wood changes. If I used solid wood, the traditional floating panel design would need to be used so that the tops and bottoms could expand and contract as the moisture content varies from Summer to Winter and back. The old masters knew what they were doing, and likely all learned the hard way. Only modern plywood is stable enough to not require the floating panel technique when gluing a box together.

Charley