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Old 02-03-2015, 11:55 AM   #1
Kristopher Shifler
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Join Date: Feb 2013
Location: Chambersburg  PA
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Jump Box

I know that there are probably 100 plans out there for 3-height boxes, but I couldn't find one exactly like this. So I drew it up and made it this weekend, and it turned out well. Thought I'd share it if anyone was looking for jump box plans.

What I was looking for was a box where each side is supported by two other sides, no matter which way the box is turned. For example, in this plan B side is supported on two sides by A, C side is supported on two sides by B, and A is supported on two sides by C. Not rocket science, it just seemed logical to me, but I couldn't find any other plans that did this (although I'm sure somehow has thought of this.)

I added a brace that supports the C sides (just a 6" wide scrap piece of 3/4 plywood), not shown in the plans.

This box is 20"x24"x30" and made of 3/4" (actually 23/32) plywood.
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Old 02-03-2015, 06:07 PM   #2
Matthew S Cooper
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Location: Modesto  CA
Posts: 85
Re: Jump Box

Your project turned out nicely, and I'm sure it makes for a stable and sturdy landing surface! I like the additional bracing you've added, though I don't know if it is entirely necessary or not. If your cuts are straight and you use sufficiently strong adhesive and screws, even a non-braced box is pretty strong. That said, I'd still have bracing.

Just as soon as I tear into things and change the head gaskets and freeze plugs on my truck I'll get myself some lumber for various garage gym projects. Thankfully it's a 460 Ford and not hard to work on; on the other hand pulling those cast iron heads is a minor workout in itself :-)
PR's: Deadlift 455lbs | Squat 425lbs | 100m sprint 10.62 seconds | 100km cycling 3hr, 6min | sprinter -> BMXer -> roadie -> and now CrossFit
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Old 02-04-2015, 10:10 AM   #3
Tighe Crovetti
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Join Date: Mar 2013
Location: Collegeville  PA
Posts: 359
Re: Jump Box

I've built several boxes for friends. I do the following:

2 pieces at 28.5" x 23.25"
2 pieces at 28.5" x 19.25"
2 pieces at 24" x 20"
1 piece at 18.5" x (scrap, roughly 3-4")
1 piece at 22.5" x (scrap, roughly 3-4")

The first four pieces make the sides, connecting with alternating butt joints. The last two pieces listed are glued and nailed together in a cross, and then set in the interior of the box to form inner bracing (hit with a finish nailer from the outside in). The other two pieces are secured as 'caps,' so to speak. All joints are glues and counter-sunk screwed.

My thinking is, when you're jumping on the 30" box, that surface is supported completely, all four sides are underneath you, you're not relying on the joints. When you're jumping on either the 20" or 24" surface, which is quite wide, you have the additional inner bracing to help support you.
"Obsessed is a word the lazy use to describe the dedicated."
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