This is the main two-part enclosure after the extensive modification required to mount the PC and monitor, keyboard and PCBs. Since the enclosure is steel I opted to weld as much of it together as possible in the interest of simplicity. Most of the front panel is cut away for the monitor and keyboard, so the ribs that are welded in also add rigidity. A continuous steel hinge is welded to the front panel and then bolted to the enclosure to join them together.

The touchscreen monitor will mount to the ribs on three sides, allowing the PC components to attach to the VESA mounting holes on the monitor through a simple, flat aluminum bracket. The keyboard will be sandwiched against the inside of the front panel with a flat steel plate.

The interface elements on the right side of the front panel are connected to a large PC board that includes the Arduino and charge pump circuitry. A smaller board isolates the relays, most of which will be switching AC power.

The original concept was to pack everything into the controller box so it would be a standalone assembly, but I came to understand the risk of packaging higher DC voltage components (like stepper drivers) into the same box as sensitive logic-level components (like a PC). So the motor drivers and their power supply moved into the base of the milling machine, mounted to a welded steel assembly that will mount into the base through an opening cut through the back. The pink datum planes in the screenshots represent the interior space available in the upper half of the machine’s base, which is pretty much consumed by the electronics.

Next up is the PCB design for the interface board in the controller box…

CAD files:
smoker.stp
smoker.igs
wood_rack.stp
wood_rack.igs
charcoal_basket.stp
charcoal_basket.igs

And here’s an unmodified 55 gallon drum model (minus some of the details, like lid and caps, etc.) in case you want to create your own design:
55gallondrum.stp
55gallondrum.igs

Here’s the bill of materials: