Pi-Amp Rev. 6
This is an simple, sturdy and cost effective chassis. Required tools are a table saw with a non ferrors blade, drill w/ assorted bits, jigsaw, flat file, tap, center punch, and orbital sander (or elbow grease).
- Aluminum Plate - 67 US$
- Aluminum Angle - 18 US$
- Machine Screws - 12 US$
- Shipping - 45 US$
Total - 142 US$
Weight - 13.1 lbm.
Chassis Mechanical Drawings
- Chassis is made from 5052 aluminum plate. Cutting layout shown below.
- Chassis plate is joined using 3/4" x 3/4" x 1/8" aluminum angle brackets. Bracket layout shown below. Here is a printable version of the bracket layout.
- Side Elevation.
The following link is for the Side Vent Hole template.
- Plan Elevation.
The following link is for the Top Vent Hole template. The template repeats twice and overlaps in the center column of holes.
- Front Elevation.
- Rear Elevation (as viewed from the inside of the chassis).
- Drill #36 holes in angle brackets and tap for #6-32 machine screws. Align the brackets to their appropriate position on the plates, mark the hole positions on the plate and drill 5/32" holes.
- Cut the toroid transformer mounting bolt slot in the toroid bracket and drill 5/32" holes for the mounting brackets.
- Rear panel attached to base with Mini-ITX and PC power supply templates attached.
The following links are for the Mini-ITX I/O, Mini-ITX Standoff and ATX12V templates.
The following link is for the Intel Mini-ITX Specification
- Use a junk mainboard, cut to Mini-ITX dimensions, with standoffs installed, to confirm template position.
- Cut out mainboard and power supply apertures. Test fit of mainboard I/O shield. It should snap in and out with slight pressure. Rear panel complete with exception of speaker wire binding posts and amplifier power switch (note - need to update rear panel template and mechanical schematic to show location of binding posts and RCA jack).
- Layout the face plate templates in preparation for marking.
The following links are for the Left, Center and Right templates.
- Center punch all holes in preparation for drilling.
- Drill all holes for heat sink fins, power transistors, PCB standoffs, and controls. I drilled pilot holes only for center panel switches until type finalized. The large hole for the USB port (make will be discussed in the Amplifier section) was drilled with a bi-metal hole saw. Ensure panel switches are in hand before drilling final hole size. Also note the counter sunk holes for the PCB standoff machine screws. Panel is buffed with 220 grit using a random orbit sander and finished with #0000 steel wool.
- Tap the holes for the heat sink fins and PCB standoffs for #6-32 machine screws. Layout the heat sink fins, starting at the top and bottom, mark and drill with a 5/32" bit. Fasten the heat sink fins with #6-32 x 3/8" socket button head machine screws driven with a 5/64" Allen wrench. The heat sink fins are lapped with 400 grit wet-or-dry and polished with #0000 steel wool. They must sit dead flat on the face plate for good thermal conductivity.
- Inside of face plate showing #6-32 x 1.25" machine screws for mounting amplifier PCB's.
- Front panel complete with exception of opening panel switch holes to final dimension.
- Attach the face plate to the chassis base.
- Assemble the chassis cover using #6-32 x 3/8" socket button head machine screws.
- Fit the cover to the chassis base.
- Secure the chassis cover to the base using #6-32 x 3/8" Phillips head machine screws. Feet will be attached after amplifier is complete.
- Build the drive head as shown below.
The following link is for the Drive Head template and the 2.5" HDD Mounting Specification.
- Install the drive head to the face plate with the four center machine screws from the top two heat sink fins. These screws should be 5/8" or 3/4" in length in order to penetrate the face plate and drive head bracket. Also shown is the final test fit using a scrap mainboard and power supply.
- Install 1/16" thick power transistor Plexiglass shields. In this revision I heated and bent the inside ends for added protection from wandering fingers.
- With exception of a few component specific holes, the chassis is complete and ready for the amplifier.