Plywood boxes, how strong?

[Robert Mickley]

We had a discussion a short time ago about vertical loading on plywood. I believe it was Brian who had bought an edge sander and was looking to mount it. Some one else piped in with designing a fish stand to hold about 1500 pounds.

well it got me to thinking about how much will plywood stand. So off to the shop and with out much planning I whipped up a box. Now there was two reasons for this. Since we have limited storage space( hey Live in a trailer) we sometimes have to be creative in storing things. The wife needed two boxes too store her pressure cooker and her canning pot in so they could kept in the storage shed.

Box is about 15.5 inches on all sides. Mitered corners with two face frame biscuits in each joint to keep the edges aligned. The bottom is dadoed in.
NO screws nails bolts or chunks of iron. 1/2 inch oak ply that was left over from a previous project

Now that green thing in the picture is a 2940 JD. Weighs in at 12,580 with me on the seat. I know this because I've driven it across the scales at the grain elevator to many times to count. The oak board on under neath was there since the ground outside my shop isn't level, the top one was to keep the forks from damaging the edges.

If I was to hazard a guess I would say that box is holding up around 4500 to 5000 pounds.

[Steve Clardy]

Looks like a great test Robert!

[Ray Bersch]

As I said to Brian last week, I'd ride that to the moon. Boxes are pretty strong - 'course, if you move just one of them back wheels a little you'll end up with all flat pieces - but that's not the point - great illustration.

Ray

[Vaughn McMillan]

As I said to Brian last week, I'd ride that to the moon...
I dunno, Ray. I think that John Deere might get a litle drafty after about 50,000 feet. :rolleyes: Then again, the forks would be handy for picking up moon rocks. :D

I wish I still worked in a materials testing lab with a compression testing machine. Used to break a lot of concrete test cylinders on it back when I was still in high school. It'd be pretty easy to set up a semi-scientific test to see how many PSI you could load on the edge of a piece of plywood.

- Vaughn

[Brian Parker]

Wow that's pretty impressive there Robert. To quote some ppl at a tractor pull... you 'got er done'.

Ray is correct in that plywood will hold quote a load. From what I gather in reading more of the strength is derived from the glue than the wood itself. Thus the more layers the plywood is the stronger it is.

I think if you use all glue vs all brads or nails you will get alot more strength as fastners come out and bend under loads sometimes whereas glue greatly increases the ridgity and strength of the box.

All in all I think its a great visual, hopefully others will be able to benefit from this simple yet practical test. BTW Ray I hear NASA is recruiting hehe jk,...I couldnt resist :D

[Robert Mickley]

I got news for you Vaughn, that tractor is drafty all the time, especially on cold mornings haying cows.

Brian
Your right more layers more strength, and some of that was 3 layer stuff.
On occasion we (especially me) tend to over engineer projects. I have to watch or I'll be using 2x4's where a 1x3 will do just fine.

Ray that was the one thing that worried me was racking the box when the front end came off the ground. Trust me I just didn't drop the forks on it and push.

Steve, I don't know how great a test it is but it was fun,

you all should have an idea now that I may try anything just for kicks. Don't worry if I had crushed the box I would have posted it too, oh though the thread title would have been more like "Well that didn't work" :D

[John Hart]

Nice Box Robert!!

(note to others: I got to see the box today at Robert's house. It is indeed storing a pressure cooker. I think the pressure cooker is safe);) :D