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I'm looking to make some relatively large boxes for tools (currently one for a bunch of air tools, and one for a router, plunge base, and bunch of bits) out of 1/2" (~12mm) baltic birch plywood.

The sides will be joined with glued box joints, but I'm a bit unsure about attaching the bottom. My original plan was to cut a 1/4" (~6mm) deep groove about 1/2" up from the bottom on each side and end and inset the bottom panel (also 1/2" plywood) in that, much like a drawer bottom but glued in place. The other option is just to do a flush bottom glued in place and reinforced with some brad nails.

Essentially... thoughts on how the strength would compare between:

  1. a glued bottom set into a 1/4" deep groove, 1/2" up from the bottom
  2. a flush bottom glued inside the sides/ends and then reinforced with some brad nails
Jason Antman
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    Please look at the search results for "plywood box". I think this is much discussed already. As usual, the answer is "it depends". –  Oct 20 '21 at 16:44
  • TBH, for carrying heavy stuff like tools, I'd dado the sides and put the plywood in using glue & nails. However, I'm pretty sure @jdv is right that this has been discussed before, and that the answer will be "it depends". – FreeMan Oct 20 '21 at 18:08
  • I admit I'd probably do the easiest thing and just glue-and-nail around the sides. Nails are pretty strong when used to depend on their shear strength, and the glue is insurance. More insurance might be some simple triangular plywood feet on each corner that overlaps the two sides and bottom corner. –  Oct 20 '21 at 19:44
  • (Though, given I own a Kreg pocket-hole system, I might glue-and-screw using that because it would be even faster.) –  Oct 20 '21 at 19:45
  • I did not want to include this in my answer as I don't know for sure, but I think old crates did not glue on their bottoms. I have seen many weapon crates and hundreds of ammunition boxes and no evidence of glue is visible, only nails. – Volfram K Oct 20 '21 at 20:27
  • @jdv Thanks for your extrapolation. Yeah, I think I've read every question on here about plywood or boxes. I guess I'd been hoping for... something new, and more? – Jason Antman Oct 20 '21 at 21:06
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    Did you find this one in your searches, Strong method for bottom of a box? It's actually listed in the Related column at the right of the page. Anyway, it pretty much gives the standard consensus WRT this query. FWIW I suspect there's be no appreciable difference between your two options, if you do the second one well (bottom fits accurately, enough glue, plenty of brads/nails) I doubt it could fail with any reasonable loads (and a few unreasonable ones!) given this is Baltic birch ply. – Graphus Oct 21 '21 at 08:01
  • @Graphus yes I found that one... multiple times in fact. It's the closest I could find to what I was looking for, where rollin-shultz actually gave some anecdotal information about the thickness of plywood he uses for shop drawers that expect to hold up to 100 lbs. I guess I'd been (naively) hoping that someone would pop up out of nowhere with... sheer strength test results for various bottom attachment methods? – Jason Antman Oct 21 '21 at 11:45
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    Jason, you overthink this I think. Only one of my sister's pans, big casserole or Dutch oven, weighs more than a 2 000 W plunge router. And same drawer has 2 fry pans, griddle plate, salamander (?) and more! If this is not assurance even Ikea drawers can hold 55 lb. Weight all air tools and if total is higher you already know you build from much stronger material :) – Volfram K Oct 21 '21 at 23:27
  • @VolframK shrug I overthink pretty much everything... – Jason Antman Oct 22 '21 at 20:39

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I think your answer is 1 because inside a groove the wood must break for the bottom to fall. It seems all strong drawers for kitchens, usually made of weaker particleboard in Europe, are made this way. I don't know the weight of a bunch of air tools but many cooking pots must be more than a router, base and bits. My sister has collected cast iron pans and her deep drawer must hold greater than 20 kilos.

Option 2 is probably ok however. I would use strong nails as I do not own a nailer, but many brads must be as strong as a few nails and the glue will add much strength.

Volfram K
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