Re: Material Thickness for Pickup Bed Toolbox

On Thu, 11 Oct 2007 21:43:39 -0700, with neither quill nor qualm, Jim
Frame <jhframe@xxxxxxx> quickly quoth:

I have a plywood box in the back of my pickup that holds long stuff
(tripods, prism poles, digging bars, shovels, long stakes, etc.). It
has stood up well to the loads I've placed on it, but after almost 15
years of exposure to the weather it's falling apart.

I'd like to replace it with an all-aluminum box for reasons of
durability and appearance, and maybe even some weight savings. However,
I don't know how thick an aluminum top I'll need to obtain the same kind
of performance I've gotten with 1/2" plywood.

The current plywood top spans openings ranging from 10" to 18", and it
hasn't balked at being jumped on or having sacks of concrete and sand
stacked on it. I'll need the aluminum top to do the same thing. Since
I'm interested in saving weight and cost, I'd like to find the sweet
spot between weight/cost and a top that's too thin to bear the load.

Is there a formula that would allow me to size the aluminum top for this
application, or is this a
seat-of-the-pants/try-it-and-see/if-at-first-you-don't-succeed proposition?

Aluminum diamond plate comes in 0.125" thickness and is fairly common.
Check the specs on 3003 and 6061 alloys, MSC's choices of diamond
plate.

0.080" is also common, but how many bags of cement do you want on top
and how sturdy is your frame? More fasteners (and/or a single ***
top) means more weight-carrying ability for thinner stock.

After looking at MSC's prices ($30 s/f), I'd look for a local scrap
yard to source it if I were you. Ye gods! 4'x4'x0.125" is $168 at
MetalsDepot.com, or 4'x4'x0.060" plain steel *** is just $45 (or
roughly $3 s/f., with $227 FedEx Freight shipping on top) <thud>
Yeah, you'll just have to find it locally, won't you?

Vendor metalstogo on eBay is much cheaper for al di plate, though.

16 Ga. steel *** is 2.5 lbs per s/f, 14 ga. is 3.12 lbs per s/f.
1/8" aluminum plate is less than half that weight with equivalent
(SWAG) strength.

--
Reading well is one of the great pleasures that solitude can afford you.
-- Harold Bloom, O Magazine, April 2003
.

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