Design of a lightweight box

Stuart Ablett

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Tokyo Japan
I have a customer that wants a lightweight box, it will be about 13" wide, 6" deep by 42" long.

This customer is a friend of the family that practices various martial arts, he has various practice weapons that he takes with him to the training center. Now he is using a bag, but it does not work well for some of the weapons, and it does not protect the weapons from being banged around.

The weapons are made from aluminum, and are EXPENSIVE to buy, they are only used in Kata, not stuck against anything, so they are fairly lightweight and somewhat fragile.

My plan, thus far, is to make the corners of the box from some hardwood, I have Ash on hand so I'll go with that, and the flats of the box from some nice 4mm thick plywood (5/32"?).

The box will be about 4" deep on the bottom half and 2" deep on the top half, both halves will be used for stowing weapons.

This is the joint I have worked out, I think it should be strong enough, I want to only glue it, no fasteners................

case_joint_1.jpg case_joint_2.jpg

case_joint_3.jpg case_joint_4.jpg

case_joint_5.jpg case_joint_6.jpg

The lip of the box also gets a strip of hardwood.

case_joint_7.jpg case_joint_8.jpg

case_joint_back.jpg

The outer edges will be rounded over on the router table (as soon as I put new bearings in my Hitachi M12 router!!).

Do you think that regular Yellow carpenters glue will be good enough for this?

I do have some Gorilla glue, but I've not used it much, and when I did, it was not the best of times :rolleyes:

This is just a mock-up that I made to see how it would work, it is tacked together with some CA glue, the joints are not PERFECTLY tight etc, but it will give you some idea of the way it is designed and made.

Hints, suggestions etc please!!

Cheers!
 
i`d use yellow glue stu........plenty strong so long as you`re able to bring the mating surfaces together with sufficient pressure....tod
 
Stu, before I got to the part where you describe what you've got alreay, I was thinking about some thin (1/2" or better 3/8"), quarter sawn spruce with narrow box joint fingers.
 
Thanks Tod, I really would rather avoid that Gorilla stuff :rolleyes:

Dave, I was thnking that too, but this thing will take a fair bit of abuse, and the thin solid wood would be more likely to crack (?) and it would bruise more than the plywood....would :D


......or at least that was my thinking....:rolleyes:

Cheers!
 
Well, I'd say your thinking is correct. :thumb:

I think with the corners as you have designed them, you could bevel the inside corners and bevel or round over the exterior ones.

If the contents would allow it, you might consider designing the box so the sides and top are curved a little to increase strength.
 
The inside looks a bit clunky/chunky on that mockup. I would agree with Dave about beveling the inside corner, but that would make it trickier for you to glue.
 
What about narrow (4mm ?) finger joints directly on the ply then maybe 3/4" triangular glue blocks on the inside corners. to stiffen it a bit more? Or are you trying to avoid showing plywood edges?
 
Yeah, I'd rather not show the plywood edges.

I thought about just a 45 on the insides, but then it all gets really small and would be tough to clamp etc.... :huh:

A small round over, to knock off that corner on the inside would be good too, maybe I'll just do that.....

Thanks guys!
 
Art, yes, I think that is close. I was actually thinking of a slightly larger cove so that there's almost a feather edge where the post meets the plywood. The outside could be rounded over similarly.

I did this several years ago on a small box of mahogany with maple corner posts. The idea worked well but I didn't put the cove on the inside edge of the posts. I didn't like it that way at all. It is a neat method of joining the corners and you can make the corner post stock in long pieces like a molding and then hack off pieces to suit. It is much like a common method used for building cabins on some wooden boats. It is desirable for in that case because you end up with no exposed end grain once the coach roof has been added.
 
An update.

I took your advice about a cove on the inside, I really like the way it looks, thanks for that!! :thumb:

But, I could not do the vertical pieces, the "Corners" so to speak.............

cove.JPG
Yep, like the look of that!! :)

cove_cove.JPG
This, as you can see, did not look do good...... :rolleyes:

cove_square.JPG
So this is what I'll have to go with, the corner will get eased over by hand. the vertical piece is only about 2" long on the lid of the case, and about 5" long on the the bottom of the case.


One quick question, cutting out the corners to accept the vertical "posts" for the corners, I used my dado stack, and it leaves these extra deep marks on the outside of the cut. I'm guessing that it is to cut the fibers so stop splintering, but in this case, I had to stop a bit shy of the depth I wanted and I'll have to do a little paring by hand.

dado_marks.JPG
(might be hard to see...)
the question, is this normal for a dado stack? I have never had this one sharpened (it will need it soon).

dado_set-4.JPG
This is the dado stack, Dimar from Canada, got it through Lee Valley a while back. Mine is the 8-24.

Cheers!
 
Stu, if you've got a core box bit for cutting the cove, you could do a stopped cove on the corner posts so it matches the cove along the bottom.

My dado set does that, too. It's a Jesada. If I care about the look of the dado, I usually cut them with a router bit to avoid that.

If you are going to have the set sharpened anyway, you might get those teeth ground down enough not to leave a groove at the shoulder. Or maybe leave less of one any way.
 
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