How To Build An Easy 3-in-1 CrossFit Jump Box With A Single Sheet Of Plywood Video 

Thank you for the video dude!

awesome thanks

kirk earl . hi . I'm confused. when you were telling measurements. at first you said . 20 - 19-28-28 1/2. . den all of a sudden it was . 20-19-28 1/2-28 1/2. which is it ?

Sorry. See correction in video description.

Sweet! Glad it worked out.

Hello, how much did Lowe's charge you for the cutting? Thanks

@@FerchitoMexico Lowes cuts anything for free... as long as they are straight cuts

great idea, having lowes do the cuts. =)

Jay Elliott glad it worked out

One other update... The box was slightly off on two corners where it wobbled due to the cut issue I mentioned above. Anyone else having this issue can fix it pretty easy. Just back out your screws and insert a shem or something like a paint stir stick in a corner that needs adjusting, move it to get the feel just right and then screw it all back together. Also, unlevel flooring like in your garage can cause it to feel not level.

Kirk Earl didn't mention taking the kerf (width of the blade) into consideration for laying down the measurements. Typical blade width for table and circular saws is 1/8". So laying out the measurements all in one go without cutting each piece and remeasuring you are gonna lose 1/8" every time you run a pass of the saw. That is how your cuts came out wrong. Next time, calculate in 1/8" per pass of the saw blade or run 1 measurement at a time. Measure twice, cut. Measure twice for the next panel. Cut. Wash, rinse, repeat.

@@HighSpeedChase762 This is it! Reply is spot on. This is a major key!

Sure it does. It works the same way a ceiling beam or door headers do in a building. The load is transferred from top to the beam/cross brace to the side walls and down. This is a quick and easy way to build one of these that nearly anyone can do with a single sheet of plywood, a saw, and a drill. It has zero sponginess at all and I'm not a lightweight dude. What percentage of viewers wanting to make one of these do you think have the tools and skills to do a box joint? Maybe

@@kirkearl Ok, I see your point but if it's a single beam, it would normally go wider than there the load is going straight down like a window lintel/ beam so the load is supported under there the pressure is. As you've also put the top board on the inside of the sides, it's putting a lot of pressure on the supporting screws. I weight 90+kgs so would opt for something more. A box joint is super simple if you're shown once. It can be done with a hand saw and would inter-lock all the edges. Wasn't a dig, just an observation/ solution.

The only side of the box that is not fully supported is the bottom. The other 5 sides are all supported. Jumping on the bottom is the same height as jumping on the top, so no height options are lost. More lumber is easily added if you want to drive your truck over it, but this video is about how to build with a single sheet of plywood. I'm 200 lbs and can jump on all 6 sides with zero flex of the box... even the less supported side.

Use google to convert

Yes and should. The bracing in this is definitely not the best or smartest.

+Stephanie Doyle Same here.

+Stephanie Doyle Thanks for commenting. The shortest side benefits from being braced by both walls which are under its surface. Adapt it how you like though for your needs. I am around 200 lbs and feel no flex on any of the sides.

Yea...well, thats like, your opinion man.

@@felsal20 The Dude abides

I just froze the frame at the beginning and then jotted down the dimensions as he talked. Keep in mind, the blade eats ~1/8" with each cut so they need to make sure they cut into the scrap piece if that makes sense. I learned the hard way and had to buy an extra piece.

3 of the sides have support behind and one does not, so the opposite. Even the side without bracing on the back holds me without flexing and I'm 200 lbs. So there are not really any support issues with this box, unless someone weighs more than that or is doing something more aggressive with it. Easy to add one more board inside though, if you want.

+David Hanson Glue definitely wouldn't hurt. This video was meant to show the very simplest method using as few materials as possible. I've used it for a year now, as is, I even use it a work bench for things like welding sometimes. No screws have come loose and it is in as good of structural condition as it was on day one. Not using glue also allows me to take it a part really easy if I wanted to replace a side or something. A lot of people would put a ton or internal bracing in it as well made of 2x4s. I just don't think it is worth the weight for the little unnoticeable strength gain.

The size and shape of the remaining scrap isn't enough to span the entire distance. If you modify the design you might be able to do it. I would suspect you may have to purchase a little extra lumber, or at least change the cutting layout on the single sheet. The only real purpose of the internal brace is to support walls that don't have the benefit of 4-wall support. In the current design the bottom side of the box is the only wall not benefiting from the support and since the height is redundant we just don't jump on that side. However, we probably still could. The entire structure doesn't lack for strength and I am a pretty heavy guy.

I can absolutely see how someone might think that if they are assuming the brace is just dangling downward from from top board and not reaching the bottom, however that is not the case. Is is attached not only to the top board but also to the boards on both ends of the brace. I do a marginal job of explaining this at 7:40. So in total the brace is attached to three boards. It does add significant rigidity when jumping on any of the three sides the brace is screwed to. It does not add any rigidity to the "bottom" side of the box if you were to turn it over and jump on that side. I explain that part at 8:19. In the main orientation of the box, with the brace up top, you kind of have to think of the brace like you would a roof truss or the brace under a wall shelf. Both a shelf brace or roof truss hold the weight above them by transferring weight to the sidewalls, not by reaching the floor themselves. Hope that helps explain it. I do agree that it looks a little odd and it would absolutely be even stronger if the board went to the bottom. This design is limited by the amount of wood available in a single sheet of plywood, so there you have it. I am around 200 pounds and this box has zero flex. Cheers.

Correct. Most wood sheeting in the US comes in 4 x 8 foot sheets as the standard. Scale accordingly larger or smaller for your needs.

Sorry about that dude. I used to have an annotation on the video correcting that, but RU-vid did away with annotation notes. I just went back in today and added a note on the video using RU-vid's new poll feature.

kirk earl Oh that’s awesome! In the end it’s getting a lot of use! So that’s all that matter cheers!

Even a 2x2 like 10 ft long. Why not put something in and it will last forever

Nick Vitale Pretty sure I just used 2.5 inch gold screws from Home Depot. Probably the longer the better as long as you drive them straight and don't bust through the side.

You bet!

The wood is 3/4 inch plywood or a fractional width really close to that. There are different grades, but they are mostly just cosmetic, so purchase whatever you can afford. The cheaper stuff wont look as nice, but that shouldn't matter for your intent. I'd just buy 3 inch gold construction screws, available at any home depot or lowes. You'll need a table saw or a skill saw and the ability to follow the instructions in the video closely. Find someone to volunteer to help from the team that has some woodworking skills. Good luck!

jpz1997 it’s been awhile since I made this so I don’t recall how much scrap there was, but yeah if you’ve got scrap and want to add extra bracing that’s no problem. Lots of comments below about people wanting to add more bracing to make it even stronger (and heavier) and that’s fine. I made this from a single sheet of plywood and it’s been bomber for years. I’m over 200lbs and it doesn’t flex on any side.

kirk earl so it’s still working for you with only that one brace? Thanks for that quick response man!

jpz1997 yeah. That one simple brace adds support to 3 of the walls. Then two of the walls that aren’t supported by the brace are fully supported by sitting atop all 4 perimeter walls. This leaves a single wall, the bottom, which has the least support, but it still doesn’t flex from my weight. That said I rarely jump on the bottom because there are 5 other sides to choose from.

@@kirkearl Perfect! I will be building this this weekend thanks!

That is a good point. Since this box is meant to be usable on multiple sides it becomes inevitable that with this simple design at least two of the sides of the box are going to not have the luxury of the piece sitting on all four side walls. On my build one of those happens to be on the "top" of the box, hence the brace piece under it. The bottom of the box is the other side that ends up in the same situation with the board being held in place with only the shear strength of the screws. I did not brace the bottom side, because there is no need to jump on that side because it is a duplicate height. For this build I chose to have the other orientations benefit from having the board rest on top of 4 walls. In the end it is going to happen somewhere without a more complex build design, and I admit that it is weird aesthetically that in my video it appear to be the top of the box where it is happening, but really the "top" of the box is whichever side is facing up when the last person uses it and changes all the time. If I were building these for a commercial gym or something I'd over-engineer it and put extra bracing everywhere.

The wood is plywood not solid wood, so their is no uniform grain. I don't know a ton about woodworking, but those two cutting terms don't seem like they apply to manufactured boards. Regardless, I've got cuts going in multiple directions, so if it was a solid piece of wood the answer would probably be, "both." Almost any multi-purpose saw blade should work just fine.

If you buy it at Lowe's or a hardware store like that and you show them all the measurements etc they can cut it for you. They have tablesaws and do it all the time

collectorbob810 There is a lot you could do to brace this internally, however if you build it as specified it needs no additional bracing. It is incredibly rigid in all positions. I weigh close to 200 lbs and don't notice any flex. This simplicity is nice because these can get heavy and are a pain to move around (big ones), so as much as you can do to not need additional parts...

point taken. i didn't think weight would be an issue.

I think weight of the box is probably a bonus to keep it from sliding around or rolling

Probably a bad idea. It will end up strong enough for a light person if constructed very carefully, but the problem will be that many of the screws need to be sunk in to the edge (side) of the boards, leaving you with a 1/2 inch target. That doesn't give much room for error. I personally wouldn't do it.

Thank you

Thanks for the comment. You can easily add that if you want. This particular vid is about making one with a single 4x8 sheet of plywood. It can safely hold a person on 5 of the 6 sides with the current design. I've got no problem with it having an unused bottom side. That said, I am 200lbs and can stand on the bottom without any give as is.

+Mark Fox I think his ceiling is covered in climbing holds, so if he slips off he doesn't land on the hard floor.

+JMM4886 Haha, could even create a new drill.

End grain attachment is fine, just drill a pilot hole first so the plywood doesn't split.

The gold construction screws I was using did not have a very large diameter and as long as the screw was well-centered I never had any splitage and I didn't drill pilot holes. The plywood was around 3/4 inch thick and the screws are quite a bit less than 1/4 inch thick, so it is pretty safe. I have still not had any problems after a year. What I would do is try a few screws without pilot holes and just go slowly as you sink them in. If there are no problems I wouldn't bother with the pilot holes. If they do start splitting or you notice any expansion/bulging in the wood, then drill. Good luck!

Well here's what I ended up doing. Plywood specific blade on a circular saw, I used a 4' level clamped down as a fence for the saw to get straight cuts. It would have been impossible to cut perfectly along the line without a guide/fence. When assembling the box, I used a 1/8" drill bit to make pilot holes. If I didn't, the wood did in fact start to split/separate, and also the 2 pieces would "wander" a bit, and it was hard to get them to stay exactly where I wanted (at least at the start). I used 2 1/2" gold screws, and had to install using an impact driver. I stripped the first few trying to use a normal drill. But once I had the technique down, it was pretty easy. I used a jigsaw to cut out handholds, and did that BEFORE installing the last side of the box so I could remove the scraps. I'm a perfectionist, and finished off by using a planer to even out the edges (some of my cuts were not perfect). I'll probably sand/plane the edges a bit, so I don't bust the hell out of my shins, and maybe add some kind of felt or thin foam along all the edges as well. Anyway, thanks for the video, it got me started, and I'm pleased with the finished project!

I'd guess maybe 30lbs

+tkotomy Good catch. Not sure how nobody has called me out on that mistake before. It should be 28.5 for the last two sections. If you add it all up you will get 96 inches total, the width of a sheet of plywood.

kirk earl No problem! I had eventually just added them up though I don't usually use imperial so it didn't immediately occur to me that 96" was your total span, ha! I guess you could just add an annotation on the video (but if nobody noticed it then no big deal)

Hi. It has been a couple of years since I built this, so I don't remember the exact site. I did a quick google search just now and it looks like The Art of Manliness site has something similar, but theirs seemed to be a video also and not a dimensional printable plan if that is what you are looking for. Sorry I can't remember the original source. I don't think it would be any easier to build though if I could find it because all it covered was the dimensions that are in the first 2 min of this video. Sorry that doesn't help much. Good luck building!

Shevin Sacrey climbing gym pads

Skixxle sorry. See correction in video description.

Super easy if you have a table saw

+Chris Thornley I'd maybe increase the number of screws used and it wouldn't hurt put a bit of wood glue at the joints before screwing it together. I am around 200lbs and I don't feel any flexing at all, so it would probably be just fine. If you are using it for the intended purposes most people are landing on it at the apex of their jump, so it doesn't recieve much more force than the persons weight. Quality 3/4 inch plywood is really strong stuff, so I think it will work great for you. The design in the video results in a box with braced support for 3 of the 4 sides, so there is a bottom of the box which has less support than the rest of the sides. Mark that side "do not jump" for good measure.

+kirk earl Hey well thanks I appreciate the advice brother

Hey Hector, I would make and sell you one, if you haven't already gotten one.

Sorry about that. The video has a big annotation box pointing that verbal error out, but if watched on some mobile phones the annotations get stripped from RU-vid videos unfortunately. If anyone knows a different way for me to make a note in this in the video please let me know. This shouldn't have caused you to lose $30 though. You'll just need to trim 1/2 inch off on the corresponding boards and everything will line up fine. You'll end up with a box that is 1/2 inch different than mine, but still great. Again, apologies.

+Authentic Beast It's a climbing gym