(This bookshelf is very sturdy and isn't going anywhere soon, so Please vote for this project in the Indestructables Contest in the upper right corner of the web page where it says, "Vote!")
I had located four dining room table leaves that were being given away through Craigslist for free (only the leaves without the tables). I did have to remove the end edges of the table leaves, as they weren't needed for this project. After deciding that I wanted to use the leaves as the shelves for the bookshelf, I set out looking for a way to accomplish that task.
During my research, a sturdy metal server rack became available at our hackerspace. It had previously held security monitors, printers, a computer, and a sound system. Those items had been relocated, freeing up the old server rack for a new purpose. I decided it would make an excellent base for holding up the table leaves as shelves, with the addition of some scrap 2x4's and plywood (We keep a stash of scrap lumber in our workshop). We eventually realized that the original metal shelves from the server rack could be attached to the sides as additional storage. They would also serve as bookends to the shelves, as it was decided they should be mounted offset to the wooden shelves.
If you can find an old server rack that is being thrown out, recycled, or for sale on the cheap, then you can build a bookshelf similar to this one. Since table leaves might be hard to find, but you could easily replace those with scrap lumber, 3/4" plywood, MDF, 2x4's, or even 1/2" slats. However, some additional reinforcement may be necessary if your replacement is not strong enough to hold books across the span of the shelf.
This instructable was an afterthought to the whole process, so I apologize for not having photos of every step.
Step 1: Parts & Tools Review
Old metal server rack. The one we used was made by Hoffman Enclosures Inc.
Scrap lumber for use as shelves: Plywood, table leaves, MDF, 1/2" or 3/4" wood slats. Cut to the size you want your shelves to be.
Scrap lumber for use as shelf supports: 2x4's worked great for ours, but any wood slat large enough to hold a bolt will work.
Optional: Old metal server rack shelves.
#8 size wood screws (#6 size may work if you already have them). Quantity of 28+
"L" brackets quantity of 16 (four for each of the four middle shelves)
The "L" brackets I used called for #6 size wood screws. I had #8 size, so I used them.
1/4 inch bolts, 1/4 inch nuts, and 1/4 inch washers. Quantity of 16 of each.
A quantity of eight additional washers that your screws won't slip through. (These are for attaching the top and bottom shelves).
Hand held power drill and drill bits.
Circular hand saw or table saw.
Work bench or work area.
Drill press (optional, use the hand held power drill)
Screwdrivers: standard and Phillips head.
Socket wrench set (to tighten the bolts)
4 to 6 large clamps
Step 2: Prep the Server Rack
I removed the four center cross beams that were holding the two sides together at the top and the bottom. Notice that the cross beams at the top are horizontal and the cross beams at the bottom are vertical. I discarded these pieces into our scrap pile, but you may find some other use for them. With a small enough shelf, they could be reattached at the longest setting, but my shelves were too wide for that to work. The rack I used is adjustable to a maximum width of just over 41 inches. Just short of the width of my shelves. You could choose to use a shelf size that is at 41 inches wide or smaller. Then you can keep the center cross beams in place and just adjust them out to the width of your shelves.
I was then left with the two opposite sides of the server rack. Once the horizontal supports for the shelves are in place, the shelves themselves will rest upon them providing the spacing between the two sides of the rack. The depth of my shelves was predetermined by the depth of the server rack itself. Since the table leaves I used nearly matched up with the depth of the server rack, I didn't have to make any adjustments to the left and right side supports at the top and bottom of rack.
Optionally, the side horizontal beams could be cut down or replaced with something else shorter to serve that purpose. Then new holes could be drilled into the support beams or whatever replaced them. Unless you need shelves to have less depth, I would advise against doing that. If you do choose to go with a more shallow shelf, the original server shelves will not fit the smaller size. I left the two sides of the rack as they were at this point, since my shelves fit that depth, I wanted to have very deep shelves for the books, and I wanted those original metal shelves to be mounted on the outer sides for extra storage.
Step 3: Add the Side Shelf Supports
Measure the length of the side supports to match the depth of the server rack from what will be the front of the bookshelf to the rear of the bookshelf. For me, this was about 20 inches for each 2x4 that I cut, two for each shelf, for a total of eight. The boards have to be long enough to fit between the sides of the server rack frame without being too deep for the frame. At the same time, the boards must be long enough for the bolts to hold them in place.
The next part is the most important step in the process.
The server rack shelf mounting holes will then need to be measured and marked on these support boards and the 1/4" holes for the bolts drilled with a drill press. This measurement was somewhere between 16" and 20" for me. A hand power drill could be used for this purpose, but it is important that the holes be perfectly perpendicular to the board. I regret that I don't have any photos of this step, as it is crucial to the side supports fitting and being level. The holes must be drilled through the boards at exactly the right location for the bolts to attach them to the rack through the existing holes in the rack frame.
I held the boards in place and level, then used a sharpie to mark where the holes should be drilled. After drilling one set of holes in one support board, I tested the fit of that board. I created a temporary jig for the drill press, then placed each board into that jig to drill the holes. I flipped the board end to end, then front to back between each hole at either end. Without these holes in the right place on each board, the supports either wouldn't have been level in the frame, or they may hold the frame too far in or push it too far apart at the center. Then the original metal shelves wouldn't have fit on the outer edges. *In retrospect, one of the original shelves could be used to mark the support boards and create a jig for the drill press, provided it wasn't bent or warped. I used the server frame itself to mark mine.
Once all of the horizontal support beams are drilled, they can be mounted in pairs level with each other on the frame.
As option to this step, the original server shelves could be used as your supports for the bookshelves and save yourself some time. Holes could then be drilled in the bottom of them with a hand power drill, they could then be attached directly to the shelf materials with screws and washers. I didn't do this because I wanted to use the original server shelves on the sides of the bookcase. Plus, the original metal shelves have sides that would hang down under each bookshelf, making it more difficult to see books on the shelves.
Step 4: Add a Shelf to Each Set of Support Beams
I estimated that I would want the top shelves to be a little bit shorter in height than the bottom two. This is completely adjustable due to the server rack mounting holes. If we want to adjust the height of the shelves later, we can do so. We could even add shelves if we wanted. I chose about 14 inches for the top 3 shelves leaving about 22 inches of space for each of the bottom 2 shelves.
Once the first shelf was clamped in place on the horizontal supports, I was able to tape the "L" brackets in place near the four corners. The clamps are important to keep the edge of the shelf flush and true with the edge of the horizontal support. I then used a hammer and punch to mark the center of each hole for in the "L" bracket. I then used a hand power drill to pre-drill four holes in each "L" bracket. That makes 16 holes per shelf. Once the holes were drilled, I installed the screws and mounted each of the brackets for the shelf. I think removed the clamps and repeated this step for each of the four middle shelves.
Once they were in place, I added the top shelf of plywood, and screwed it into place using the existing holes in the edges of server rack and the interior top support beams. I pre-drilled these holes as well, then placed a #8 screw through a washer before screwing it through the holes and into the wood.
I then laid the whole bookshelf down on the backside and measured the depth and width of the bottom shelf. Then I cut it to the right size with a handheld circular saw on the work bench. This last shelf was mounted to the horizontal support beams at the bottom with four screws and washers. Then I stood the shelf upright again.
The original metal shelves were then flipped and mounted on the sides with the original screws and hardware.
Step 5: The Finished Bookshelves.
Books, magazines, and games have yet to be installed.
Further planned additions include LED lighting on each shelf, an All-in-one computer to log the books in and out, and acquiring some Kindle or Nook e-readers for the storage and reading of electronic books and documents in our hackerspace.
Special thanks to John R., Ryan H., Ryan W. and the other members who offered advice and / or assistance and those who listened to me ramble on about the creation process of this Bookshelf for our Library at Arch Reactor.