Monthly Archives: October 2010

A Quick Wooden Computer Case

 

I recently decided to build a wooden computer case, despite the fact that I’ve never really liked wooden computer cases. The project came about because I realised that I had enough spare computer parts in my cupboard to build a reasonable computer. I don’t have room for another computer in the house, so I decided to build one for the garage. The plan was to make the computer as cheaply as possible from spares; the problem was I didn’t have a case to put it in. I thought about buying a cheap case, but in the end decided that since it was only for the garage I would whip one up out of plywood.  So that’s what I did. It’s not a particularly interesting project, it’s a simple wooden case with fairly boring parts inside, but I thought I’d put up a few pictures and notes anyway in the hope they may be of interest to others who may be thinking about building a wooden case.

I made the case from 12mm thick plywood. I went looking for a sheet of the usual pine ply, but was talked into an even cheaper sheet of poplar ply with hardwood veneer. I wondered about the quality of the ply (rightly so as it turned out), but bought it anyway. The problem with the ply was that the veneer is about 0.1mm thick and chips and flakes off with the making of every cut and hole. In addition, most cut edges (which I had planned to leave exposed) have gaps where there are missing bits in the laminated layers. It would probably be fine for making a door panel fitted in a frame, but was not a great choice for this project. I ended up covering the edges and using a dark stain to hide the chipped veneer, which worked out reasonably well.

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Here I’ve cut the side on which the motherboard is mounted. I’ve added another square of 6mm ply under the motherboard in order to lift it up a bit more. This moved the cut-out for the connector plate further away from the edge of the back board, making it easier to cut. The block of wood beneath the motherboard is a spacer for the power supply, also used to move it away from the side.

 

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As I did with the server cabinet, I used small rubber grommets as stand-offs and screwed the board down to the plywood.

 

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There were a number of slots to cut, all of which I did with a router using wooden templates and a template guide on the router. This is the slot for the connector plate. I was able to use plywood offcuts to make templates since the perfect template thickness for my router guide is 12mm. You can see in the photo that for square or rectangular holes like this I just mark out the hole size with template offset added (two times the distance between the edge of the the template guide and the edge of the router bit), and then plunge cut the hole in the template with my drop saw. It’s quick and easy and makes a perfect square (or rectangle). The fact that the cuts extend beyond the bounds of the hole does not matter. Because I’m cutting right through the board here, I’ve placed another sheet of scrap ply underneath to stop the router cutting the table. I recommend making several shallow cuts, as cutting the full 12mm all at once is too much for the router.

 

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And here’s the back of the case with all slots cut. I try and make very careful measurements (vernier calipers are indispensible for projects like this), but even so, the perfectly snug fit of the metal connector plate was a pleasant surprise. You can see that the router bit leaves rounded corners. These can be squared with a chisel, but I just left them as they were. The large hole is for the power supply, which will sit at the bottom of the case. It seemed easier to put it at the bottom rather than have to construct a sturdy shelf at the top, however it does make cooling more of a challenge.

 

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This photo shows the PSU cut-out from the back. The PSU hole has a recess on the inside into which the PSU fits. This helps secure it. To cut the recess, I made a template to cut the exact outside size of the PSU when using a 12mm router bit. I then cut the through hole with a 6mm bit, which made it 6mm smaller than the PSU in each direction. Keeping the template in place, I switched to the 12mm bit and cut the recess to a depth of 7mm.

 

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In this photo I’ve glued the back and base to the side and temporarily installed the motherboard to assist with positioning the hard drive and PSU. I only intend using the one hard drive, which is held in place with a simple friction restraint (a “Z” shaped metal bracket screwed to the base board). The drive sits on a rubber pad to reduce vibration, and will eventually be earthed to the motherboard with a wire.

I guess I should say something about the hardware. The mother board is an Intel D975XBX2, A.K.A  “Bad Axe 2”. I actually won it in a computer mag competition, along with some other parts. I used it for a while in a computer, and found it to be a difficult board to overclock, although stable at the right settings. The processor is a Core 2 Duo E6600, one of the original Core 2’s. The first Core 2 I bought was an E6600, but I later sold it. The only piece of hardware I didn’t have for this build was the CPU, and CPUs compatible with this board can no longer be purchased new. I found a reasonably priced E6600 on an auction site. The guy even threw in the custom “Freezer Pro” cooler, which I don’t think is a great cooler, but probably better than the stock job (I’m a big fan of the Thermalright ultra-120 extreme CPU coolers). My preferred hard drive brand is Western Digital, and luckily I had a spare WD 500GB drive for the build. Most of my data is stored on my home server, so my client computers only need one modest drive. With regard to drives, I decided to go all futuristic and not include an optical drive. Actually, it’s probably more that I wanted to keep the case as simple and compact as possible. It isn’t as hard to cope without an optical drive as you might imagine. I now buy and download most software and music etc. from the internet, and software on DVDs can easily be transferred to a USB flash drive on another computer. That’s how I installed Windows 7 on this machine. The graphics card, not installed in the photo above, is an Nvidia 8800GT with a nice quiet aftermarket cooler.

 

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I spent a while thinking about how to fit ventilation fans to the case. Because the computer will be operated in a potentially dusty environment I did not want the case to be under negative pressure. I decided that two 12cm intake fans would do the job, one on the top feeding air to the CPU cooler and RAM, and one at the front blowing across the hard drive. The fans would need  filters which could be removed from the outside, as this case will not be as easy to open up as a metal one. My solution was to cut an 110mm diameter circular hole with a jigsaw, then rout two recesses on the outside face. The first recess was a circular 130mm recess centred over the hole and cut to a depth of 8mm. The second was a 134mm square recess centred over the hole and cut to a depth of 6mm. The result is shown above. To make a grill to retain the filter cloth, I cut the bottom out of a small garden sieve and trimmed it to fit into the circular recess. This is held in place with some hot melt glue. I then positioned the fan over the hole and marked, drilled and countersunk the holes for the fan retaining bolts. I chose bolts with countersunk heads so that they would be flush on the outside. Over all this went a square of filter cloth (vacuum cleaner motor filter), cut to fit into the square recess.

 

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Finally, I made a removable wooden grill from some 5mm think strips of pine. The grill was sized to fit into the square recess, and was screwed down over the cloth with four pan head screws as shown. The panel on the left is the front panel, the other is the top panel. On the front panel you can see that I’ve also drilled out a 16mm hole for the power switch, and above that a 3mm hole for the power LED. The thread on the power switch was not long enough to go through 12mm of ply, so I recessed an area behind the switch hole with the router.

 

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In this photo it’s all starting to come together. I’ve fitted all parts, installed Win 7, and am testing the system stability with Prime 95 whilst monitoring temperatures with Everest (two invaluable programs for the computer builder). You can see the little white power LED above the switch. As well as the left side of the case, I decided to also make the top panel removable. This makes it easier to replace the top fan, and to remove the motherboard. To secure the top panel, I screwed it to a wooden rail which I glued near the top of the three fixed sides. The removable side panel also has a wooden rail glued around the inside. Three of the top screws (missing in the above photo) screw into the side panel’s rail, helping holding the side on. I decided to make more of a decorative feature of the screws by using cup washers.

 

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There are a couple of things to note about the back. Firstly, you’ll notice the wooden plug in the end of the video card slot. I had to make these slots a certain length in order to be able install and remove the cards. The metal return on the card bracket sits on the edge of the ply, which stops the card from rotating downwards. However, because of the slot length, when you plug in the cable, the pushing tends to rotate the card out of its slot. To stop this I made a tight fitting removable plug. The second thing to notice is the aluminium strip screwed over the lower slot. Ultimately the slot above it got one of these too (note: the blue light is from LEDS on the front fan – not intentional, it’s just that I had this fan going spare). I cut these two slots because among my spare parts I had a WiFi card and a Creative Audigy sound card. Once I got the thing powered up I quickly learnt several things: Firstly, useful WiFi reception was not available in the garage, secondly the WiFi card was not compatible with Win 7, and thirdly, despite Creative’s Win 7 drivers, the Audigy card did not work at all well with Win 7. Ultimately I decided to extend wired LAN to the garage, and use the motherboard’s built in sound chip (at least for now). The slots were thus superfluous, and were covered up.

 

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Another shot of the back. Here you can see the small white reset switch. I installed it into a recess so that it is flush with the back. I hoped that this would help avoid accidental pushes.

 

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This photo shows two more modifications. Firstly, I found that things were a bit warm because hot air could not easily escape the top of the case. There’s a reason why most cases have the PSU at the top. The solution was to cut some top vent holes in the removable side. These have some mesh behind them to discourage spiders. Secondly, I found that the removable side needed to be held in by screws at the front and back as well as top and bottom. The wood had a tendency to bow out otherwise. I thus added a row of screws down the front and back. The back and underside screws are just normal countersunk screws.

 

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Then I decided that the exposed plywood edges were just too shabby, and milled some thin strips of pine to glue over them, which is what’s happening in this photo. I didn’t bother with the edges at the back.

 

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And so to finishing the case. I had to strip everything out again in order to sand, stain and varnish the case. I started with this light brown stain, but ultimately decided to go for a dark brown finish, better to cover up the veneer chips.

 

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Here’s a shot of the case inside. You can see the wooden rail below the top edge. I’ve also added another strip down the front inside to take the decorative front screws.

 

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And here’s the inside with everything refitted and ready to go. Notice the wooden stop screwed in behind the PSU to stop it from moving backwards. The PSU hold down “Z” bracket is screwed into this stop.

 

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Finally, the end result. Stained dark brown and finished with four coats of polyurethane. I must say that it ended up looking better than I imagined.

The HP monitor is one I repaired.  One day after a few years of use it started smoking alarmingly. I wrote it off as dead, but didn’t throw it out. Eventually I did some research, and with a few dollars worth of parts ordered online, and advice from folks on the Badcaps forum, was able to replace the burnt out transistors and get it working again. Brilliant. Now all I have to do is clean out my messy garage so that I have somewhere to put it!


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