Materials

The Chassis

Aluminum is easily machined, light and rigid, resists corrosion and has excellent thermal conductivity.

Aluminum Plate, 0.125" thick. Alloy 5052. The advantage of 5052 is cost. The other alternative, 6061, is 33% more expensive than 5052. Alloy 5052 has a medium machinable rating meaning you will spend additional time deburring after drilling holes. Alloy 6061 has excellent machine ability and can be anodized. If you plan on using surplus plate, then don't worry about the alloy type. If you plan on purchasing new plate, you will have a choice. The chassis is designed to stand alone without the case because 0.125" plate provides sufficient rigidity. Do not attempt to substitute thinner plates for those pieces specified as 0.125" thickness.

Below is a suggested cutting guide for a piece 36" x 48" (a common size).

Pi-Amp Bi-Amp Chassis Cut Guide

The Main Board Tray

Obtain a surplus micro ATX PC case. An ATX case will also work although additional cutting will be required. The older the case the better because it will be made of heavy gauge steel. There are plenty of junk PC's laying around! The object is to obtain the I/O and add-in card bracket and main board tray. Simpler if they are one unit. The photo below shows a main board tray from a discarded e-machine.

Pi-Amp Micro ATX Main Board Tray

The main board tray must trimmed to fit the space allowed in the chassis. This is done readily with a jig saw with a metal cutting blade or circular saw with an abrasive blade. Smooth the edges with a flat file or hand held grinder.

If the main Board tray comes from an ATX PC, the card bracket must also be cut down from six slots to four.

Electrical

Total cost for materials - 1,590 USD (September 2011).