Thursday, January 02, 2014

Buiding the Box (Building MAME: The Cabinet.)

When looking at all available designs and previously built MAME cabinets you soon find out that there is not just one universal design. And actually if you take a closer look at all the original cabinets you'll see they also differ a lot.
 I decided to take the 'Defender' design which is available as a Sketchup model. Imported it into the free 'DesignSpark' solid modeller and just projected the side of the box  on the piece of MDF I had available. This also gave me the chance to make it less deep. Since my cabinet will be fitted with a slim LCD screen instead of a bulky monitor it can be a lot smaller than the original. From the model I created the following plan-view of the side:
From there its just a matter of transferring the design to the board and use a jigsaw to shape them.
It's hard to saw straight lines using a jigsaw, so I first clamp on a piece of wood to align the saw. And when you just clamp two identical pieces of MDF together when you are sawing you get two perfectly identical sides.
Note that sawing two layers at the same time like this probably only works if you use 8 to 10 mm MDF. If you use it on thicker material it is very hard to keep the jigsaw exactly vertical and if it is slightly tilted your lower board will have a different size than the top one.

After I created the two sides I just estimated the optimum width by just holding the monitor next to one of the plates and finding good position. 50 cm seems like a good width so I just made the second MDF board exactly 50 cm wide. By doing this very carefully and making sure all corners of the board are now exactly 90 degrees it will be easy to create all front, top and rear surface plates.
And then we paint..and paint
and paint..and paint...
 Yes, two layers of MDF primer on each side is the minimum. Because MDF sucks... And that I mean literally. It just sucks up paint so for a good final finish you just have to primer it first.

Drilling the holes for the buttons. Using a 28 mm speed drill creates nice clean holes, but you must drill half way from one side, reverse the board and drill the rest from the other side.
Glue on the supporting blocks. I used a 20x20 wooden stick that I found in the shed. It's painted wood so using wood glue is not optimal since that is supposed to be applied to unpainted surfaces. Using a Polyurethane based construction adhesive is better.
In the mean time I keep refining the 3D model. And it's actually progressing faster than the real thing:

But after assembling the main parts it starts to look like real:
Next step would be to create the perspex cover for the control panel. I chose a standard 100x50 cm, 2mm thick perspex sheet which is available at almost every large hardware store. It was actually a coincidence that I chose 50 cm for the inner width of the cabinet but it's very convenient now since the perspex only has to be cut to length. And cutting perspex appeared a lot harder than I expected. First I tried to saw it using a fine pitch wood-saw intended for cutting laminate flooring. That does not work. The cut is very irregular and pieces just tend to break off. Second I tried cutting it using a hobby knife. This might be possible but its very hard to get one straight cut. Even if you use a steel ruler as a guide the knife just runs off if you are not very careful. After creating the cut (it's impossible to cut through the perspex) you can break it on the edge of a table. That does work but if the cut is pot too deep and not very straight you will get a very irregular edge with razor sharp points.
Finally used the blade  of a fine tooth hack-saw. That works better but it is essential that you carefully support both sides of the cut or the perspex will break.

Then the holes. This turned out to be even harder and it took me three attempts and a full panel of perspex before I finally had one that did not have cracks, or even completely destroyed edges. My tips for making holes:

Hole saw
- Use a vertical drill and push the drill very slowly. If you drill too fast the perspex will crack.
- Start every hole by drilling a small (3mm) hole in the centre. Then slowly increase the size of the drill but not more than 2 mm for every next step.
- Drill any hole larger than 10 mm using a hole-saw ! Trust me, any other drilling device (like a step-cone drill for example) will crack the perspex. This has one disadvantage. The arcade buttons require a 28 mm hole and this somehow seems to be a very uncommon size. So far I just found one set that has the 28 mm included.
- Support the perspex with wood and use a fresh piece for every hole so there is no hole in the wood under the perspex before you start the drilling.

 - Make sure you push down the perspex firmly and close to the drill. If you don't, the perspex might just jump up and crack.
- Don't drill too close to the edges. If there are holes near the edge of your control panel (like there are on mine) make the sheet larger, drill them first and then cut the sheet to size.

But finally with the inside painted deep-blue and the control panel covered with the perspex sheet it starts to look really good:
Creating the front bezel was actually very simple. First cut the perspex to size, place it in the cabinet and install the monitor so you can see were the screen is. Mark this on the perspex (I kept about 1 cm marging around the actual screen). Then (using a very sharp knife and a steel ruler) cut the protective foil and remove it on the edges. Then spray paint it a few times until the edges are really black. Make sure it really dry before removing the protective foil from the centre. And it looks really awesome when you look at it from the other side.

With the front-bezel installed, running LadyBug:
On the pedestal, with the top marquee installed:

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