Help with a joinery question

[Joe Borelli]

Well my woodworking joinery skills have progressed from the nail and screw era through the dowel and biscuit phase and now I am at the dovetail and finger joint point. My question is on constructing a box or chest with finger joints or dovetails. Are there any types of joints to use on bottoms and/or tops that will compliment the strength and elegance of the dovetails and finger joints of the sides? I know drawers are constructed with dados to fit the bottoms in but in heavy box or chest construction, what joint would compliment the dovetails and provide high strength on the bottom to prevent contents to fall out through the bottom if a heavy load is picked up? It seems a shame to construct a box or chest with beautiful dovetail sides and then just nail or screw the bottom on.

[Ken Fitzgerald]

The bottoms are typically set in dados in the front, back and sides just like drawers.

In fact, planning is used to hide those dados so they aren't visible OR easily concealed.

[Mike Ontko]

Yep, it's Just like Ken said. If you're planning on storing heavy items in those boxes, you could construct the bottom from 1/2" or 3/4" material. And, it'll be even easier to reinforce that structure if you're intending to build a base or some other form of supporting platform.

[Lee Schierer]

You make the bottom as Ken and Mike have stated and you vary the thickness of the bottom according to how much span and load you intend to support. A square piece of thin wood supported in a dado on four sides is really strong.

[Joe Borelli]

Thanks for the advice folks. The dado was what I was thinking also but I just wanted some opinions from those that have done this. You can look at hundreds of pictures of dovetail and box joints but none ever show the joints of the bottom.

[David Eisenhauer]

I can't imagine a box load that you will still be able to pick up that would require more than 1/2" thickness for the bottom panel inserted in the all-around dado capture. In fact, 1/4" - 3/8" is probably plenty strong enough. I have built many storage boxes for various purposes over the years and believe that I have never used fatter than 1/4" for anything.

[Andrew Pitonyak]

For some boxes, I have simply glued the bottom board in place. For example, a small box to hold tooth picks and a box that holds some chisels. I have some purchased boxes where this is also done. Well, I purchased stuff that came in a box; for example, a set of chisels, router bits, and similar. When I did this the first time on a chisel box, I did not expect it to hold or last, but it was a fast box that I threw together (well, as much of a hurry as you can be in when you cut dovetails by hand), but, the point is that I did not really care how it looked, or, if it fell apart.... it was a test. The box is probably 6 years old (give or take) with no issues. The box does not experience wide humidity swings either.

One of my more recent chisel boxes, I aligned the dado that I cut on the top and bottom (to hold the top and bottom boards) so that in one direction you could not see the dado. For the other ends, I did a stopped dado (well, I think that I did... I have done this in the past). I could have avoided the entire problem by using half blind dovetails. Some people just fill in the end with a piece of wood cut to fill the hole.

When I made the tops and bottoms, I cut a rabbet so that the top and bottom of the board would sit flush with the sides. If you do not care if it is mostly flush, you are essentially make a frame / panel design so that the top and bottom can float. If you just really do not care about looks, or, if the tops and bottoms are flush (then they do not stack as well), then you can just cut a dado that is not flush as you generally do with drawer bottoms.

I have seen some designs where the top just slides into place. I have not seen that on the bottom

[Reinis Kanders]

For smallish up to 8x11 utility boxes/trays I frequently glue a thin 3/16 or so pine bottom, pine is relatively stable.

[Joe Borelli]

I was thinking of larger chests and boxes, up to around 36" x 24" that would hold up to 75 lb or so.
Joe

[Andrew Pitonyak]

I was thinking of larger chests and boxes, up to around 36" x 24" that would hold up to 75 lb or so.
Joe


For boxes of that size with significant weight, it is common to screw and glue strips on the bottom of the chest inner walls and then the chest bottom is screwed to that. You can then easily change the bottom if it is damaged. Well, I think that is what they do. Check out those large floor tool chests that Swartz has written a book about.

http://lostartpress.com/products/the-anarchists-tool-chest

Just a thought.