Wednesday, October 29, 2014

Building a Server Rack

When it comes to electronics, whether you are talking about computers, communications, or sound, the serious gear usually comes in rack-mount cases. Often, you can pick up used gear that is a few years old for not much money. Unfortunately, the racks themselves don't get obsolete, so even the used ones are pretty expensive. This means that you may end up paying more for the rack than you did for the equipment inside it.

Luckily, a real handyman can build a rack much more cheaply than he can buy one.

My main computer cluster lived on cinder blocks for months before I got around to putting it in a rack. Not only was this setup hideously ugly, but the vibration from the fans resonated the blocks and translated through the floor joists to make a constant hum that drove my downstairs neighbor nuts (that was OK, he already didn't like me). I decided to build a proper rack. When I went online, though, most of the designs I found were made out of dimensional lumber and looked almost as ugly as the cinder blocks.

The Cinder Block Approach

Working from a cabinetmaker's sensibilities, I designed the rack that I built this week on the show. It is structurally efficient, better looking than most of the home-made racks on YouTube, and channels the air flow from the fans through a particle filter to keep dust and hair out of the machines.
You can build a rack the size of mine for under $50. Without even counting shipping or assembly costs, this is less than half what an equivalent store-bought rack would cost. I chose the dimensions mainly to make the best use of a common furnace filter from the hardware store. You could easily make it twice as tall and use two filters, or find a smaller filter and make it lower. You could also go without the filter, but I would only recommend this if you were running your computers in a fairly clean indoor environment. Computers suck a lot of air and any dust in a room is going to end up in your fans.

If you are using this for radio amps or stereo equipment you may want to adjust the width and make the cabinet a bit shallower; most amps I've seen are not nearly as deep as a server computer.

Measured Drawings

A high resolution .pdf file, suitable for printing, can be downloaded here.

Or, you can take dimensions off these screen shots. You may need to zoom your browser to read them:
Panel and Frames

Casework Construction

Door Construction

Step by Step

  1. Cut out the OSB pieces, using a table saw or portable circular saw.

  2. Cutting OSB Panels on the Table Saw

  3. Cut pieces of 2x2 softwood to go all the way around the bottom deck. It is easiest to mark the 2x2 directly from the bottom deck and cut to the mark with your saw. Attach these cleats with glue and either clenched nails or drywall screws

  4. Adding Cleats to the Bottom Deck

  5. Cut out the face frame. Optional: If a jointer is available then rip the pieces a little bit oversize and use the jointer to make sure the edges are perfectly square. When crosscutting the face frame pieces to length you will want to use your squarest saw and, if necessary, clean them up with a disk sander or a block plane. If you are working with portable tools, you may want to build a shooting board to use with your hand planes.

  6. Build the face frame, using your preferred joinery technique. In the video I use a pocket screw kit. Biscuits or dowels would also be a good choice if you have either a biscuit jointer or a doweling jig. If you don't have any of these three and are thinking about investing, I would recommend a pocket screw kit because it is the most affordable option and the most frequently useful under job site conditions.

    You can also just drill dowel holes freehand after carefully marking and center-punching the locations. This is a very slow way to build face frames, but it does make acceptable joints.

  7. Building the Face Frame

  8. Sand all of the joints flush on the front of the face frame.

  9. Attach the face frame to the cleats on the bottom deck. Leave a 2 1/2 inch space between the front of the face frame and the front of the bottom deck. Attach the the frame with either pocket screws or dowels.

  10. Attaching the Face Frame to the Bottom Deck

  11. Attach the side panels to the bottom deck and face frame, using glue and either drywall screws or 1/4" pneumatic stapler. Be extra careful not to split the face frame.

  12. Attach two 1x2 cleats around the back opening of the cabinet. Use either screws or staples with glue.

  13. Cleats Around the Back of the Cabinet

  14. Attach more pieces of 2x2 horizontally across the back opening, keeping each piece exactly level with the corresponding rail on the face frame. Hold each piece in with glue and a 3" deck screw.

  15. Place 2x2 blocking between the face frame rails and the 2x2 rails in the back of the cabinet. Use 9d finish nails on the face frame side and common nails on the back. For larger equipment (like a 4U server or an interruptible power supply) you will want to use 2x3 or even 2x4 blocking, or add another piece down the center. Use straight pieces of wood. A bowed piece will make it hard to get your equipment in and out.

  16. Blocking to Support the Equipment

  17. If, like me, you left extra space for future equipment cut a piece of cardboard or poster board that you can wedge or staple in to cover the gap in the face frame. This will keep the equipment fans from drawing air from the hot side of the rack.

  18. Add a few pieces of 1x4 blocking across the top of the the cabinet. These will give you something to screw the top panel to and will make it sturdier, in case some fool decides to sit on your rack.

  19. Sand everything flush at the top of the cabinet so the top panel will have an air-tight fit.

  20. Attach the top panel. Use screws without glue so you can get in if you ever decide to modify the rack at a latter date.

  21. Build the door frame, using the same process you used for the face frame.

  22. Cut thin cleats to hold in the filter. Getting the cleats the right thickness can be tricky, as you want to hold the filter snugly and also have a relatively tight fit with the case to minimize air bypassing the filter. You will probably want to chamfer one edge of the cleats with a plane or on the table saw to get more clearance for opening the door. Use fine brads to hold the cleats on wile the glue dries.

  23. Optionally, add a few strands of cord or wire across the cleats to hold in the filter (an old boot lace would probably work well). Mine fit tightly enough that I didn't bother with this step.

  24. Add hinges and a latch to the door. I used small strap hinges and a magnetic cabinet latch but other types would probably work. You may need to chop out pieces of the cleat to get enough space for the hardware. You can also add a knob or handle to the door, if you want.

  25. Closeup of Hinge and Door Cleats

  26. Hang the door, adjusting the hinges and latch as needed.

  27. Install your equipment. You may need to plane or pare away some wood where the fit is too tight.

  28. Installing the Equipment
Now you know how to build nice racks for electronic equipment. Hopefully, this means that the next time you see a wicked awesome tube amp or web server at the swap meet, you won't have to pass it up because you'll be able to build a place to put it.

The Finished Rack Cabinet

For a better looking cabinet you could easily build this using plywood and hardwood, then paint or stain it. Or, if you are into high performance applications (bitcoin mining?) it would be pretty easy to plumb this with copper water lines or peltier junctions for cooling. As designed now, though, it will should fine for a small computer cluster for an office or a research group.



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  2. Kevin:
    Thanks for this, but the link to the PDF 404's. No worries, your images are detailed enough that I'll draw up another set in LibreCad and SketchUp