Need a structural engineer

[TheClaw]

I'm building a workbench with two 46in boxes side by side. I'm going to set them in the frame of the workbench 'ala @Steevo style. Do you think I can get by with 2x4 lengthwise underneath them or should I go with sistering two together or use a 4x4 frame?

I'd like to get by with just 2x4s if possible. And yes, I'm surfing the workbench threads here on GJ

 

[PCustoms]

Do you need a stamped drawing?

 

[TheClaw]

Do you need a stamped drawing?

Sure, you got one?

 

[PCustoms]

Sure, you got one?

I've got a fresh box of crayons


Sounds like your question is can a 2x4x8' ( I assume wood) support 2 loaded toolboxes.

The answer is going to be no. You'll have to add some bracing at minimum.

A 4x4 does not add anything here.

 

[mngundog]

Considering the weight is designed to be supports by 4 wheels at the corners, fastened by a small piece of metal 3"x5"(maybe), I wouldn't doubt a 4x4 would offer the same if not more support than the wheels do. Not an engineer, have slept at a Motel 6, and my set-up for the last 12 years have been supported by plastic trim molding instead of wood to prevent rot, and moisture wicking up onto the metal.

 

[Stuart in MN]

It's not clear what you're doing. Is the 2x4 holding the tool boxes up in the air, or is it sitting on the floor like the base of a cabinet and the tool boxes are resting on top of it? If it's the latter there's no problem, it's not like the tool boxes will crush the 2x4.

 

[TheClaw]

I don't have any crayons but I can copy and paste. My question is about the bottom beam. Based on what you guys are saying I'm thinking that needs to be either 2 2x4 screwed together or a 4x4.

Raising it up because I like the top surface higher and I stash things like jacks and oil pans underneath.

 

[BD55]

Is there a reason you can't put a support underneath the midspan? Or does that factor into fitting jacks and oil pans under there?

 

[TheClaw]

Is there a reason you can't put a support underneath the midspan? Or does that factor into fitting jacks and oil pans under there?

I'm thinking about putting it on wheels. New shop is still a work in progress and it's likely things will move around.

 

[Hank11]

A 2x6 would be better, and a vertical member between the boxes fastened top and bottom would help. Or maybe a piece of threaded rod top to bottom between the boxes. If you are filling the boxes with knitting yarn, disregard. If you are planning on rolling it around much a steel frame would be a better choice. Do you know they make longer boxes on wheels? Are your boxes 2 feet wide or 5 feet wide? That matters a lot.

 

[PCustoms]

I don't have any crayons but I can copy and paste. My question is about the bottom beam. Based on what you guys are saying I'm thinking that needs to be either 2 2x4 screwed together or a 4x4.

Raising it up because I like the top surface higher and I stash things like jacks and oil pans underneath.

4x4 is not any stronger in this position.

2x6 minimum. I still think a center support is better, or make this out of metal.

 

[Rusted Nut]

the first thing a structural engineer will want to know is how much weight are you putting in the boxes.

 

[FourthQuarter]

This Garage Journal. Wood is good but not for this project. Go buy an little MIG welder, couple grinders and a couple of sticks of 1x2x0.090. Practice welding for a couple of days and sketch up your bench by night. Good luck, have fun.

 

[TheClaw]

I realized I don't have a structural issue. I have a height issue. Once I realize that all I needed was some spacers sandwiched between the casters they provided and the bottom of the box The top of the box would be the height that I want it to be. All I have to do is lay some 2x4s underneath the box and bolt the casters through those.

Problem solved.

 

[67King]

2x6 with a support with a caster in the middle.

 

[Cheep]

I made a frame for 2 older Craftsman boxes end to end out of 2x2 angle iron and put casters on the corners, has been good for 40 years or so...

 

[eejack]

Alternatively, if the top is sturdy enough, one might run a threaded rod down from the top to the midspan of the 2x4 between the tool boxes. A suspension instead of a leg as it were.

Might actually be able to do this with unistrut instead...

 

[tarmy]

You are gonna need some steel on that…

‘’Those boxes when full are gonna weigh enough to sag the hell outa wood…

some ideas for you…both of these spans have box steel frames to handle the weight.

 

[finn]

Can the wood idea and go with steel box section tubing

 

[MushCreek]

Even if the wood doesn't sag right away, it will eventually under load.

 

[TheClaw]

You are gonna need some steel on that…

‘’Those boxes when full are gonna weigh enough to sag the hell outa wood…

some ideas for you…both of these spans have box steel frames to handle the weight.

@tarmy I've seen your setup. That's exactly what I'm going for. How deep is your countertop?

 

[tarmy]

@tarmy I've seen your setup. That's exactly what I'm going for. How deep is your countertop?

30”

Here is a better view right after new top.

 

[mm08822]

Good move including the vise support underneath!

You may want to radius the corner edges to minimize splintering......1/8"

 

[JohnX14]

As others said, the 2x4 will sag with the weight. You may be able to substitute or "back" the 2x4 bottom rails with appropriate sized angle iron, and through bolt it to the legs and also to the 2x4 rail. I doubt you will want to roll the whole bench assembly once all the weight is on or in it. You could also build a stationary bench and keep the tool boxes on casters and build it so they wheel under the bench. I get that compromises you rolling equipment under those sections of the bench

 

[rattle_snake]

I used some pieces of 3" pipe as caster spacers to raise welding table. Longer bolts, and done.

 

[marak]

Consider a flitch plate if you want to use 2x4s. The Second Moment of Area is the geometric component that determines bending. For a rectangular cross section, this value is (bh^3)/12, where b = width (1.5 for a 2x4) and h = height (3.5 for a 2x4). Doubling the base doesn't help much, but increasing the height goes up fast as it is a cube. Adding a 1/4" steel plate sandwiched between two 2x4's will significantly increase the bending resistance. Bolt this system together and it will be quite strong. Strong enough for the weight? Maybe.

 

[tarmy]

Good move including the vise support underneath!

You may want to radius the corner edges to minimize splintering......1/8"

That pic is before I cleaned things up and trimmed out the top. I had just replaced it as I was adding structural steel to support it over the cabinets.

 

[mm08822]

Ha! I thought all of the blue was tubing....

 

[bluedog225]

You are gonna need some steel on that…

‘’Those boxes when full are gonna weigh enough to sag the hell outa wood…

some ideas for you…both of these spans have box steel frames to handle the weight.

Nice. I have lived my life incorrectly.

 

[MushCreek]

You could just bolt the boxes together end to end, making a long, rigid assembly that wouldn't bend the middle of the frame. That's assuming the boxes themselves are strong enough for that kind of thing, though. Maybe a plate from the two inner caster mounts to keep them from wanting to spread.

 

[Black300zx]

Sounds like you've got it figured out, but you could always add some adjustable leveling feet under the boxes mid-span. Retract them when you need to move it then extend once in place for support

 

[Stuart in MN]

I don't have any crayons but I can copy and paste. My question is about the bottom beam. Based on what you guys are saying I'm thinking that needs to be either 2 2x4 screwed together or a 4x4.

Raising it up because I like the top surface higher and I stash things like jacks and oil pans underneath.

Multiple 2x4s going from side to side, instead of just one at the front and one at the back, would provide more support for the boxes. Maybe add two more in between, equally spaced. Someone else mentioned bolting the sides of the boxes together, that would make them more self supporting too. I'd probably use 4x4s for the corner posts, for looks as much as for support.

 

[firebirdparts]

I'm an engineer, I think you want to use six casters and frame accordingly. I guess the best way to do that is to turn a 2x4 sideways between the boxes. There are other ways to do it, but that seems the toughest.

I think you'll be disappointed otherwise.

 

[senlow]

You could just bolt the boxes together end to end, making a long, rigid assembly that wouldn't bend the middle of the frame. That's assuming the boxes themselves are strong enough for that kind of thing, though. Maybe a plate from the two inner caster mounts to keep them from wanting to spread.

Mac Tools used to offer a kit to do just what MushCreek described. They called it the Box Master. I've never seen one in use.

A system like this uses the stiffness of the toolboxes to support the long span. I would not be confident that this is a viable option for lightly built boxes or boxes over 34" long. However, something like the Box Master plus a steel underframe should work well.

 

[yhprum]

Needs another leg in the middle to stop the bending of the bottom support I reckon.