When putting together a MAME cabinet you are probably going to want to include a trackball on your control panel. Using a real arcade trackball can be very expensive if you plan on buying the interface, or very time consuming and frustrating if you attempt to build an interface yourself. When I built my first MAME cabinet I already had an arcade trackball to work with. But I ruined 5 mice in an attempt to interface it with the PC. When I finally did get something that worked, I found that it worked horribly for anything other than slow, smooth motions.

I consigned that arcade ball has been to my parts bin and decided to come up with a new solution. After ruining several PC trackballs I finally found something that would suit my needs. The CompUSA Crystal Trackball.
This ball is almost as large as a standard arcade trackball and seems to be the same size as a mini arcade trackball. Interfacing this is no problem since it is a standard PC component. But there is still the problem of mounting it.

As you can see from this bad ASCII this trackball is a big square
jobber with buttons on either side (there is a third button on the
bottom but we will be ignoring that).

          |            |           
          |     ---    |
          |    /   \   |
          |    \   /   |
          |     ---    |
 button 1 |##        ##|
          |##        ##| button 2
          |##        ##|

Before we get started we will need a few things.
  • CompUSA Crystal Trackball or similar item
  • a few spare bits of wood
  • a half dozen wood screws
  • some styrofoam
  • a roll of duct tape
  • superglue
  • a chunk of plain rubber floormat larger than your control panel. (I got mine at one of those home stores).

First start by taking everything off of your control panel, and of course removing it from the machine. Take off what ever overlay you had and throw it away. Then cut a hole in the panel just a little larger than the base of your trackball. Now you need to make a little floor underneath the hole (that is what the wood is for). Different control panels will require different depths as far as this goes, but you want the highest part of the trackball base to be just below the surface of the control panel.

Now use a few of those extra screws to affix the trackball firmly in place. You should now have a control panel with a big hole in it fille by a trackball. Now cut a bit of your styrofoam off and glue it to the left button, then take a knife and cut the top part of the foam to be just below the surface of the panel (perhaps a 16th of an inch). Do the same for the other button. Now make sure you can tap the foam and cause clicks, if you can then we are on the rights track.

Now use more of your foam (along with duct tape as needed), to build up the rest of your trackball base to roughly the same level as the surface of the panel. Once again make sure your buttons can still click.

Now use your duct tape in long strips and cover the entire control panel, except for the ball on the trackball itself. You should now have a big grey control panel with a ball sticking out of it. Make sure you can still click your now hidden buttons.

Now take your rubber floormat and lay it over the panel so it covers the whole thing overlapping on all sides. Mark where the ball is. Then carefully cut a 2.25 inch circular hole where you made the mark, if you used a different trackball you may have to cut a different size hole. Now go ahead and use the floormat to cover over your whole panel. You can glue it or you can srew it in from the bottom, I used screws as it allowed me to stretch the rubber for a nice fit.

Now you should have a black control panel with a ball sticking out of a perfect hole. You can no longer see the buttons. But guess what? You can still click them, by pressing in where they would be. This allows the buttons to retain their function without breaking the illusion of the arcade control panel.

Now go ahead and cut holes in the rubber to mount all your old buttons and joysticks. If you followed my directions correctly you should have a black control panel with a rubberized surface, a trackball with hidden buttons, and whatever other controls you already had.

Now congratulate yourself by playing some Arkanoid.

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