retro design - modern functionality
The making of the model involved a range of various processes. One of the ones I used the most was vacuumforming. It was by this process that most of the parts where created.
Because vacuumeforming causes webbing at the bottom where the mould meets the base of the vacuummachine's bed, a piece of MDF had to be stuck to the bottom to raise it up a little bit.
The legs were also vacuumeformed. They could not be part of the main body mould because it would create an overhang. That would have made it difficult to make the plastic wrap around the mould and even more difficult separating the plastic from the mould.
The airvents also had to be made separately because if they had been built into the main body mould it would not habe been possible to use the mould for both side. Since I needed to make holes in the shape I decided to make two identical shapes in chemiwood using the CNC machine. Before I separated the shaped from the mould I milled out five slots in the shape positioned over where the CPU would be when installed.
The front was the most difficult part. It first had to be chromed, and then a couple of hundred clear acrylic pieces had to be slotted in evenly with 2mm spacing.
Unfortunately I lost quite a few images of this process, so the only images I got left if a couple of the acrylic ribs. I might update this with a couple of illustrations.
The two circular objects containing the powerlight and powerbutton where done on the lathe in chemiwood. The bar in between them and the two shapes on either side where done on the CNC machine. That was all assembled on a backplate and sent of to chroming. However, as I assembled it I realised that I had misplaced the position for the eject button to the DVD drive. It was too late then to correct it so the project had to continue without it.
The hard bit was to cut out the ribs and assemble them. I went through many different options with my tutors and colleagues on how to do this. Eventually I settled on stacking up a bunch on acrylic pieces and CNC the shapes. Figure 5 shows how the setup where made. At the bottom I had a 2mm styrene sheet. I glued every other rib to the styrene sheet so they wouldn't move in the CNC machine. The others might move slightly, but that wouldn't be much of an issue since I only needed every odd one. I could not glue each of them down because the dichlo would have flown up around the sides of the ribs and glued all of them together into a big solid lump. I needed to be able to separate each of them.
Then the time for the CNC work came. It would first mill out the dip, then it would mill out the shape. Milling out the dip went fine. But it went allot slower than I had thought. Because of the hard and fragile nature of acrylic I could only go down a fraction of a millimetre at the time. The dip was at its deepest 10mm. However, the nightmare truly kicked in when I came to cut out the shape. That had to cut all the way through, 25mm. The drill piece was just about long enough. Since it now was cutting the pieces loose I would have to go even slower and check up on it repeatedly as half of them where loose. Everything seemed to go fine until suddenly one of my colleagues came in and said everything had exploded. At that point I thought he was just making a very evil stupid joke as he usually do, but it turned out he was telling the truth. One of the pieces had got caught in the drill bit and it had taken a bunch of the ribs and trown them across room. It looked really bad and I would not have time to redo the pieces as it was too close to the deadline. This was already the third day of running the CNC process. After collecting all the pieces I found that the ones I actually needed was unharmed. So I began to reassemble the little jig with all the ribs. This time added more tape, as you can see in figure 7, hoping it would help.
From that point I was really paranoid and was constantly checking up on it. As the CNC machine came closer to the bottom I was in the same room most of the time, taking other parts I was working on with me. And just as it all seemed to have gone fine, with 1.5mm left, the tool snapped. And it was the last of that size as I completely shattered the other tool piece beforehand. That left me with the only option of separating the last bit by hand. Using a pair of pliers and sanding.
The fun didn't stop there. Now I had to put about 120 ribs into the chromed front shape. They all had to line up 90 degrees from the edge with an even 2mm spacing. And dichlo would not glue acrylic to any chromed parts. To stick them down I cut out a piece of clear acrylic that would slot into the bottom of the front shape. I then made a series of different fork-like jigs to make sure they got spaced evenly. I also had to sand each rib before they would fit into the front shape as the chroming had added quite a bit of thickness, especially towards the bottom.
The holes for the backport where cut out in acrylic on the laser cutter. A matching shape was cut out from the main body shape where it was inserted. Even though I measured the holes for the ports from the back panel that came with the motherboard it did not fit. I had to adjust recut a new piece.
The "Mini Media Centre" text on the sides where cut out on the lasercutter in 0.5mm acrylic. The width of the text cut out where a little less than 1mm so it was very fragile.
The stripe on the top was made from a strip of chemiwood sanded down to the correct shape. Each end where then heatbended. Unfortunately, one end unbent slightly when it was sent off to chroming. I think that I hadn't heated the material enough before bending it.
I had to get a company to chrome my chrome parts. Chroming is a difficult and expensive process and simply spraying it silver would not have worked. Even if I had polished it would quickly turn matt. I was fortunate to find a company, A.T.O.M., in London that did a special student discount for me. They applied a coat of chrome on the parts I sent them. Their way of chroming was using a special type of chrome paint which they sprayed on. Because it was sprayed the front piece ended up with some run marks down the inside. Probably because it had to be sprayed more to make the chrome cover the entire surface in between the tight corners. The run didn't really matter much for the appearance because when the ribs where inserted they covered it up. But it did make the insertion of the ribs more difficult as the chroming added some thickness, especially at the runs. I was a bit worried about how much thickness the chroming added to the text as the margins where small. Fortunately it went well.
Once I had all the pieces the assembly was quite straight forward. All the pieces fit nicely together. I wish I had spent some time during the design stage to work out a mechanism to open and close the case instead of the little tabs I ended up using in lack of time and a better solution.
The inside was terribly bodged together. I quickly cut out a frame in acrylic for the motherboard to be mounted onto. Worst of all is the harddrive which I stuck down with some insulation tape. Let's not focus too much on this bit, eh? I was always intended to be a model and not really an item for use.
Continue to the next page to see the final product when it's sprayed and fully assembled.
Copyright © Thomas Thomassen 2006-2007
MMC design Registrations: UK #4000064, More design registrations in progress