Basic question on drawer frame design

[jeegro]

edit: not a drawer, more like a drawer housing box, without the drawer.. There's a word for that...

I have some left over 1/2" King starboard (HDPE plastic) that I want to use to make an open front box and the fridge will sit on top. 2 Front Runner cub packs will go inside.

What is the strongest, simplest way to make the box? Without using a router, I think my options are basically

1. sides sit on top of bottom panel
2. sides sit on outside of bottom panel
3. sides sit inside, back panel sits outside?

Maybe add a few inside corner steel reinforcing brackets?

I'll just use flat wood screws from the outside, no pocket holes

It would be nice if they slid out, but I don't want to take the time or money to add a proper slide... can anyone think of a quick solution? Perhaps recessed ball rollers on the bottom and a stop/guide to make sure the tray doesn't tip out?

 

[Scoutn79]

Strongest way is for the sides and back to sit between the top and bottom panels. If the top panel sits between the top and side panels you will have a blowout of the top panel eventually, same for the bottom unless you have a perfectly flat floor to fully support the sides and back panels.


Darrell

 

[rayra]

sides and back sandwiched between top and bottom, as described above. Think about it. Gravity is the issue. Flat materials, wood, are strong in compression and weak in span. So wherever you can you want the material supported by material under it, rather than relying on the shear strength of the fastener alone or on the strength of half the thickness of the sheet or the strength of the glue in the lamination.

 

[jeegro]

Got it, thanks. Seems obvious now!


What about the lateral sway - especially with a top heavy 65 liter fridge on top of the box? I don't think this Starboard plastic stuff is as strong as plywood.

The box will be approx 24" wide by 32" long by 11" tall

edit: I plan to put d-rings at all 4 upper corners, and if they are secured taut to the l-track, I suppose that would hold it pretty solid?

 

[southpier]

I think "carcass" is the word you're looking for. don't be afraid to add reinforcement to any through bolting to spread the tug. and remember "triangulation" is your friend, so don't hesitate to add a three sided gusset to corners as you see fit. just stop and think (as you already have) about the dynamic forces which will be exerted on the box while in use. and figure whatever is inside will be acting as a pendulum, or maybe sledgehammer, trying to kick its way out of the box every time you take a turn side to side, up 'n' down, or stop an' go.

 

[rayra]

That's 'wracking stress' and other names for it. Building a sturdy box / module overcomes much of that. One of the nicer aspects of wood rather than HDPE plastic is that you can readily glue it together. In addition to using screws. With the plastic, I'd want screws at least as long as twice the thickness of the material and I'd want to space them no more than 6" apart. Four would be better, if there is not glue or solvent-bond joint. Too, the back end of the box prevents that wracking movement. As can the design of your drawer front(s). Having a false front that fits snugly inside the front end of your box will also prevent wracking. And you attach your cosmetic external drawer face to the false front.

 

[jeegro]

Cool, thanks. I'm using 1" #10 wood screws and these https://www.mcmaster.com/#1088a31/=17dww5u

Through-bolting the tie down rings

Ugh, based on where I've already installed the cargo l-tracks, I'm a couple inches short of fitting the fridge slide in (TBD, slide arrives Saturday, dimensions not confirmed)... I'm thinking to make a larger top piece, so theres a lip extending off the sides and back. Should be fine strength wise, but could look janky...

 

[BTCSXJ]

sides and back sandwiched between top and bottom, as described above. Think about it. Gravity is the issue. Flat materials, wood, are strong in compression and weak in span. So wherever you can you want the material supported by material under it, rather than relying on the shear strength of the fastener alone or on the strength of half the thickness of the sheet or the strength of the glue in the lamination.

I get where you're going with his. But the shear strength of a single grade 8 #10-32 fastener is over 2500lbs... 2000lbs if it's only grade 5.

I would recommend using a Kreg jig and drill. By far the strongest way to joint plywood at 90 degrees. The jig is $18.

 

[southpier]

....space them no more than 6" apart. Four would be better...

a caution here is if they are put in too close, any fastener can act as a wedge and split the wood apart. if necessary, a work around this is to not put the fasteners in direct line, but alternately angle them side to side (not front to back!) so they enter the second piece at different parts along its thickness, but aimed at its centerline.

I started this post about 45 minutes ago. with hopes of clip & pasting a picture of what I mean, I did an internet search for "toe screwing". not only do I not have a suitable picture, I am now running all over the house looking for a cigarette ....

 

[jeegro]

HDPE doesn't split, so that's going for me

Turns out my leftover starboard is just barely short of what I need . I modified the design a bit, and cut all the pieces with zero room to spare. The top piece is going to have to be 2" wider and 5" longer than the base in order to fit the fridge slide. I wanted the base to be the same length/depth, and have just the width be 2" wider on top, but alas, no more material. Waiting on some screws now from Mcmaster

 

[southpier]

not familiar with HDPE but found this: http://www.vycomplastics.com/wp-con...5/11/HDPE-Fabrication-Guide_Rev-B_2013.01.pdf see page #12

 

[jeegro]

Finished the box, aka the leaning box of beer

Without a table saw (used a jigsaw) I was kind of screwed from the start. Oh well, it works