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Help building a very simple shelf
July 17, 2014 8:13 PM   Subscribe

I'd like to build a very simple shelf that looks like this using minimal tools and at a low cost.

So far I am looking at 12" wide common wood boards that will eventually be painted. I have very minimal construction experience. I want it to look decent but not perfect (on the level of ikea shelves).

What is the best way to join the boards together? Would just using screws to join them be strong enough to hold medium weight (books and stuff). Is it better to screw down from the top/bottom or from the sides? If I don't put a back on it, will I need additional bracing so it doesn't fall over?

Only tools I have are circular saw, electric drill and the usual screwdrivers/hammer/etc. No routers, drill press, etc.
posted by roaring beast to Home & Garden (12 answers total) 4 users marked this as a favorite
As someone who isn't a carpenter but has put together a few one-off projects like this, you'll get a much sturdier end result if you use corner brackets on the inside of the joints rather than just screwing through the wood. The tools you have should be plenty for a quick & dirty set of shelves.
posted by Aleyn at 8:54 PM on July 17

Leave the horizontal boards uncut. Use two small boards as the vertical supports for the middle and top shelves. At five feet width the shelves will tend to bend under the weight of books over time, so you might consider two vertical brace points instead of just one.

The top shelf should rest on the side boards. The whole thing should be able to basically stand on its own before you put any screws in. Screw downward when possible, because that means you're attaching a crosspiece to a support underneath, and gravity is working on your side.

The ends of the middle shelf will need to be screwed in sideways, and/or brackets would help support the load. Brackets inside the outer corners will help with wobble.
posted by jayCampbell at 9:08 PM on July 17 [1 favorite]

Most furniture design questions can be answered if you remember that trees have kind of evolved to hold a bunch of stuff up in the air. You'll often see trees split, you'll sometimes see them snap under high winds or the influence of a drunk driver, but you almost never see them collapse under their own weight. So if I were doing this, I'd cut some kind of dado, maybe a quarter inch deep in the two sides and center upright and then cut the two shelves a half inch longer than the space between the uprights so that the shelves, in addition to screws in the end, are being supported by those 1/4" lips the dado creates. You can do that with a circular saw if you can set the blade depth. I'll probably be happier if you pick up a chisel the same width as your shelf boards.

The other thing about this design is that squares are inherently unstable. If you have four boards arranged in a square and you push a corner, you can collapse the whole thing with casual ease no matter what kind of joinery you use. Nail a batten diagonally across the back, or just nail a sheet of thin plywood or masonite to the back and you will dramatically increase the strength of this unit.
posted by Kid Charlemagne at 9:16 PM on July 17

For a 30" span you're going to want 3/4" boards.*

By "common wood" I assume you mean pine or another softwood, which is strong enough, but like all board lumber it will change shape with changes in humidity. Look for boards with grain that goes straight down the length and as straight as possible across the ends.

Plywood or MDF will be a lot more stable. For MDF your maximum span for 3/4" is 24". I recommend the kind without added formaldehyde.

*Just looked it up in Nick Engler's Woodworking Wisdom.
posted by hydrophonic at 10:16 PM on July 17

Corner brackets are ugly, don't help all that much and are totally unnecessary if you work carefully. With 3/4" material I would however want something to reinforce this against being pushed over sideways. You don't need a full back to achieve that; just a couple of corner gussets or a strip of thin material a few inches wide across the top of the back would do it.

JayCampbell is steering you right as to the relationships between the pieces. With solid wood boards you could even do it with finishing nails instead of screws. How well it comes together will depend mostly on the quality of materials you buy and how carefully you work. It can be tricky cutting boards to exact length with a circular saw. You should use a fine-toothed blade in that saw (not the one that comes with a new saw -- that's a cheap, large-toothed blade meant for rough work), make sure the blade is square to the base, and run the saw along a guide clamped to the board to keep the cut square to the edge and in the right place.

If you let the top and bottom overhang the sides a bit, the corner joints will be stronger and some of the cuts will be more forgiving.

Here's a plan:

Start with three 8' boards. Since the overall height is 2', the length of the vertical center divider pieces is half of 24-(3*0.75), or 10 7/8". Set up one board on a work area, clamp on your circular saw guide and slice off an inch or so from the end of the board to get rid of the beat-up, not-square factory end. Keep the scrap piece. Now cut the two 10 7/8" center dividers off that same end of the board.

Next, cut the vertical sides. These are the pieces for which you need to be the most accurate. With each of the two remaining full boards, trim an end cleanly off. The length of the side pieces needs to be the combined length of both vertical center dividers plus one thickness of the material. Theoretically this should be 22 1/2", but don't use that number and don't rely on a ruler. Line up the actual divider pieces you've already cut end-to-end, with one of the little scrap end pieces sandwiched in between, and use that to mark the length for each side piece. Again clamp your sawing guide in place to guide the cuts, one side piece from each of the full boards.

That leaves you with three boards that are still roughly 6' long, from which you take the horizontals. These are forgiving cuts; they should be square to the edges, but accuracy in the lengths isn't critical unless you want the outside corners flush; with overhangs, you've got wiggle room. Cut the top and bottom to whatever length you like. The length of the middle shelf should be the length of the top/bottom pieces minus two material thicknesses and two overhangs, i.e. with a 1/4" overhang the middle shelf will be 2" shorter than the top and bottom.

Assembly then looks like this:

Fasten one side to the bottom. Butt the middle shelf piece against it on the inside, and use the other end of the middle shelf to position the other side piece. Fasten that corner. Set that assembly up with the fastened corners on the floor, like a wide U-shape. Position the top on top of the sides. Get one corner lined up right, and fasten it. Again use the middle shelf piece as a guide to get the remaining corner joint lined up right, and fasten it.

Next attach the middle shelf. This time, use one of the center divider pieces to position the shelf at the right height. If there's any difference in the lengths of the two center divider pieces then you should use the same one to position both the left and right ends of the center shelf, so that it doesn't end up oddly angled.

Lastly, install the center divider pieces. You won't have a piece of wood to use as a positioning guide this time (unless you make one) but you can measure and rely on your eyes. Fasten one divider between the middle shelf and the top piece. Flip the unit over, position the last vertical divider and fasten it to the unit's bottom, which is facing up. Regardless of how you've been fastening the rest of the joints, this last one between the middle shelf and lower vertical divider will have to be toenailed with finishing nails.
posted by jon1270 at 4:45 AM on July 18 [2 favorites]

Jon1270 gave you excellent advice, especially

run the saw along a guide clamped to the board to keep the cut square to the edge and in the right place

Years ago, I built a number of projects (shelves, especially) using the kind of tools you have available, and I found the hardest thing was cutting squarely across the board with a hand-held circular saw (I eventually bought a table saw, which changes everything). They sell ready-made guides for this purpose, or you could use a carpenter's square and a c clamp. If you don't have a carpenter's square, now would be the time to buy one.

When I've built shelves myself, I've always used corner block construction (as in the bottom shelf in this image); I know it doesn't have the clean aesthetics you are going for, but it does have the advantage that you are always screwing into cross-grain, not end-grain, and it is forgiving of slight imperfections in your cuts.

Finally, unless the shelves will be braced between walls or other pieces of furniture, you will need some sort of bracing to prevent them from racking - i.e., folding up like a flattened cardboard box. To my mind, the easiest and strongest thing would be to attach a back. You could use the cheapest 1/4" lauan plywood from the lumber yard - they can cut it to size for you.
posted by mr vino at 5:26 AM on July 18

Do yourself a favor and get a pocket hole jig. Kreg's cheapest one is $20 and it comes with the drill bit. You don't need the fancy screws, plain wood screws work fine.
posted by elsietheeel at 5:38 AM on July 18

As someone who's made quite a bit of cack-handed furniture over the years, yes, you absolutely need to brace that thing because otherwise it will forever seek to turn from a rectangle into a diamond. All the lovely, crafty, fine details you're getting above are wonderful, but if you don't brace it, it will be crap. However nicely it's finished. When you winnow through the instructions above to plan your own structure, make sure bracing is part of it.

Just saying, cos with my first efforts it took a while for me to realise how not optional it is.
posted by glasseyes at 5:50 AM on July 18

The lumberyard will cut the boards to the exact size you want if you don't want to take a chance on messing it up. One nice way to stabilize it would be to buy a length of 2-3" wide molding trim and use finishing nails and glue to put it across the front top of the shelving unit - and maybe some half-round trim over the rest of the edges in front just to make it look nicely finished. You can get an 8' long piece of molding for very little money and the lumberyard will cut it for you also - just ask the sales person to show you what they have.
posted by aryma at 3:19 PM on July 18

Thanks everyone!
posted by roaring beast at 6:44 PM on July 18

Everybody above has given pretty thorough advice.

A couple more tips:

As aryma pointed out above, at typically "50ยข a cut/ first two cuts are free", most lumber yards will give you truer, straighter and squarer cuts than you can make with a circular saw. For a project of this size, it may be worth the two or three bucks to let the lumberyard cut out the boards.

30" is a long span if you're storing anything heavy, such as 10-12" tall books. 3/4" plywood is stronger and more resistant to sagging than a 3/4" board.

You'll want a few-dollar countersink to let the heads of the screws be recessed below the final surface, and you'll need a couple dozen wood screws in, say, #12 by 1-3/4". Pre-drill all your screw holes with about a ~3/32" drill.

Good luck with your project, let us know how you make out.
posted by AsYouKnow Bob at 9:47 PM on July 18

One more tip: if put it together and you're still worried about rigidity: besides the corner brackets that Aleyn mentioned, or the full back or even gussets, you can add corner braces to keep it from wobbling
posted by AsYouKnow Bob at 10:04 PM on July 18

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