Threaded-rod shelves

I just finished building a set of shelves that I like. They combine several salient features:

Not terribly ugly, even if the picture below right is
Have not fallen over yet
Not terribly expensive ($50ish of materials)
Feature exposed threaded steel rod, bolts, and washers, thus satisfying my steel fetish
Required only four measurements during construction, none of them critical

Self-indulgent irrelevant background material

For a while, I'd been storing my stereo, my old (non-functioning) PDP-8/f, and the house firewall in the rackmount carcass of an old DEC disk drive. The drive that used to live in the mount was a fearsome object. The permanent magnet in its voice-coil actuator measures "a handful of ferrous wrenches" on the ISO 7132 scale of magnet power, and the removable platters were huge. With the actual drive and its supporting air-handling equipment removed, the remaining case dwarfed everything I put in it. Even the PDP-8 doesn't come close to reaching the entire depth of the rack.

I got tired of sharing my room with this behemoth a while ago. The housemates always get all bent out of shape when I broach the concept of storing flammable gases at pressure in the house, so I didn't have gas tanks for my cutting torch. Hence, slicing the thing in half with the torch was out, and I decided to replace it with smaller shelves instead. Since I had the 36" threaded rods and other hardware left over from a previous attempt at building threaded-rod shelves, I decided to make another shot at building shelves where the horizontal pieces were supported by the steel rods. I was originally going to make the actual shelves out of concrete, but I lacked the patience and expertise, and I couldn't find reinforcing material. Plus, I knew my so-called friends would just laugh at me if I complained about how hard it was to move shelves made of concrete. I wussed out and used medium density fiberboard. I hadn't known about fiberboard before, but it wins my "engineered wood material" of the week award hands down. It's no mahogany, but it's stronger and smoother than particle board or plywood.
The
assembled shelves

Tools and materials

Materials:

5 19" squares of 3/4" thick medium density fiberboard plus a sixth as a template if you are prone to breaking things (I am and I did). I got mine by buying a 4'x8' sheet of fiberboard and having the evil large hardware store do the cutting on their serious saw rigs. The first four cuts were free, and it only took 7 cuts to make 10 pieces, so I definitely got my $2.25 worth on the cutting.
4 36" x 5/8" threaded steel rods
32 5/8" nuts. (These can be found in boxes---it's probably worth buying a box of them)
28 5/8" washers (I've had trouble finding these in boxes, but again, if you can, it probably makes sense to buy a box)

Tools

Drill
3/4" spade bit. It makes life way easier to have the bit be slightly wider than the rod.
Clamps (At least two)
Wrench
A shirt about the metric system to absolve you of your sins for using inches for all this stuff. The shirt is at the bottom of the page. I too am not responsible for your parents getting mad at you.

Making the actual shelves

The first step is to drill holes into the corners of the 19" squares, thus turning them into shelves. The goal here is to make sure the holes in all the shelves line up well. If they don't, then it will be difficult or impossible to fit the rods through the holes in all of the shelves at the same time.

To make sure everything lines up, I recommend that you make a master shelf and then use it as a template for the others. To make the master shelf, drill a hole into each corner. Place the center of the hole 7/8" away from the corner along the diagonal of the board. If you're as inept as I am, there's a danger that the four holes won't be in exactly the same position relative to their respective corners. So that you don't have to worry about this, make a discreet little orientation mark (I used an arrow pointing up) on a corner of the template board. As you duplicate the template, put a similar orientation mark in the same place on each duplicate.

To duplicate the template, securely clamp one or two of the boards to the template board at a time and drill away. You'll want to rest the clamped set of boards on some scrap so you're not always worrying about punching the drill through into the ground or your work table. It helps if you can get the boards to lie flat onto the scrap---this reduces the chance that you'll get splintering on the bottom of the hole as you finish drilling it. It also reduces the chances that the bit will catch partially on the scrap and torque the drill halfway out of your hands. Not that this ever happened to me.

close-up of bottom joint

A detail of a bottom joint. The tightened nuts provide force to squeeze the shelf between the washers. This force pushes the rod to remain perpendicular to the washers and hence the shelf. Note the orientation mark visible on the left shelf face.

Assembling the shelves with the rods

Once you have shelves, it's time to put them together with the rest of the hardware.

First, you'll need to build the base. Pick one of the squares to be the bottom shelf. Put a rod in each corner of this shelf with nuts and washers above and below the shelf. Most of the stiffness of the shelves comes from this sandwich of nuts, washers, and bottom shelf. To make sure everything is lined up pretty well before you tighten down this sandwich, make a similar loose sandwich on the top of the rods (make sure the orientation marks match up). Now that you know that the rods are all parallel, tighten the bottom sandwiches with the wrench. You don't need to really crank here, just make sure things are firm. After the bottom is tightened, remove the top shelf.

Once the base is tight, it's time to start adding shelves. Because the base and top will provide stiffness, you only need to support the shelves from the bottom. For each shelf, spin the support nuts to their positions. It's sometimes possible to give a nut enough angular momentum that it will spin for a couple of revolutions before you have to spin it again. Other times the nut will catch and stop. You will have plenty of time to ponder the dynamics of this rod/spinnning-nut system as you spin the nuts into place. Once they're there, drop in the washers and the shelf. Again, make sure to make the orientation marks on the shelves line up. Repeat. You can feel if a particular shelf is levelled by twisting the nuts and feeling the friction between the nut and the washer.

For the top shelf, make another sandwich for added stifness. Stick a nut at the bottom of each rod to make leveling feet, and you're done, unless you choose to mail me (rochberg@cs.cmu.edu) and tell me how bad or good you thought these directions were.

Lessons learned

These shelves are pretty narrow for traditional 17" wide stereo equipment. You'll want to make things a little wider if you want to be able to pull the equipment out forwards between the shelves.

The last time I tried this, I made several mistakes

Particleboard: It's ugly, it sags in the lengths I was using it in, and it's annoying to work with.
Too narrow drill bit: I used a 5/8" bit, which made for a tight fit with the 5/8" rod.
No clamps: I didn't clamp the shelves together when I was duplicating the master shelf.
Bad stiffening system: I didn't rely enough on the bolt-washer-board sandwich system to get stiffness. Since the holes were too narrow and poorly lined-up, the shelves ended up being pretty stiff anyways, but they were difficult to adjust.

Related work

As I quickly discovered, I'm not the only person to have instructions on shelves like this. Audio freaks like these guys and this guy spend lots of time worrying about building shelves like these with lots of vibration isolation.

I did my first (bad) threaded rod shelves before jwz put bookcase directions up but I wouldn't've gotten off my ass and webified the second ones without reading his directions and thinking "geez---mine would be way easier".