Muninn - BC-250 Case

Intro

This is Muninn, a Voron (and Corvus ATX) inspired case for the ASRock BC-250 APU boards. Like many others at this point, I decided to pick up a BC-250 and needed to find a solution for housing it. I really wanted a case for it that looked and felt premium, utilized the stock (unmodified) cooler, and maintained a small footprint. At its core, the case consists of a 2020 T-slot extrusion frame, a main component frame that houses the components (shocker), laser/CNC cut acrylic panels, and a handful of printed parts. A full build guide isn’t ready yet but I have included a few exploded diagrams and the complete CAD model to assist anyone interested in building one. 

Part Selection and Information

BOM

https://docs.google.com/spreadsheets/d/1_g3aBYG2i_X0EmiN_sCl3bp59aZ9kkBF/edit?usp=sharing&ouid=114158399205545812233&rtpof=true&sd=true

I have included a BOM spreadsheet of all of the components and hardware required for the build. Please note that the Amazon links are affiliate links should you wish to support me and continued development on Muninn as well as future projects.

Quick BOM Notes:

• For all of the bolts used in the build, button and socket head screws are technically interchangeable. 

• If purchasing your extrusions from Amazon or Aliexpress, the 400mm lengths will need to be drilled for blind joints and one end tapped and the 100mm/150mm lengths will need to be tapped on both ends. 

• At least on Amazon, unfortunately, I’ve seen the same extrusion packs ordered at different times come with different extrusion standards so the end holes could be either  M5 or M6 bolts. Both work but M6 button head bolts can be a little tricky to fit into the corner feet.

BC-250

Self explanatory. Pick yourself up one of these little guys from an online flea market of your choice. The only modification required to the module is the removal of the stock mounting brackets. I would recommend testing, installing, and flashing the module before installation.

Component Frame

There are two versions of the component frame. One single piece and a split version. Should you find yourself with a large-ish printer (>330mm on X/Y), the single piece is for you. For the two part frame an X/Y print volume of 190mm+ is required. The additional required hardware for bolting the two frame parts together are included in the BOM.

Power Supply

Any flex-ATX power supply should work in the build, though one that is modular is highly recommended. Note that if you want to unlock the extra CUs, it will draw more power and a 500w or higher PSU is recommended. 

Unfortunately, most power supplies decided to use the wrong measurement system so we do have to deal with finding the #6-32 x ⅜” screws for mounting to the component frame. If you’re in North America this shouldn’t be hard but your mileage may vary in other parts of the world.

Fan

In order to use the stock heatsink effectively, I decided to utilize a 120mm x 32mm 12v PWM blower fan. The 4 pin PWM fans plug directly into the fan header on the BC-250. I have tested both GDSTIME and Wathai fans and both work well. In my testing, fan noise has been very reasonable with this setup.

USB Hub

For the front USB IO, I’ve utilized a Ugreen 4 port USB hub which connects to the BC-250 internally. It was chosen due to its global availability but should it be discontinued in the future I will update the BOM and release an updated hub mount. 

Power Button

I’ve included files and line items in the BOM for two different power button options depending on how fancy you’d like to get. The base option is for an ATX power jumper rocker switch with a cable to connect it to the 24p ATX cable from the PSU. 

I’ve also included files to utilize an Adafruit locking RGB switch. This switch works as an analogue RGB LED and can be controlled however you’d like but I’ve included a file for an ESP32 mount that can control it via WLED. The switch's RGB pins will need to be wired to the ESP32's gpio as well as the NO and common pins to the PWR_On and a ground pin on your power supply. The datasheet for this switch is available from Adafruit on the product page. This is slightly more advanced and will require some crimping and electronics knowledge so you’ve been warned. Don’t destroy your board/PSU. And if you do, don’t blame me. 

Rear Power and IO

The base rear skirt has provisions for a D-type displayport panel mount passthrough as well as a fused IEC power inlet. An up angled displayport cable is needed to run internally from the board to this passthrough. 

At the moment, I’ve been unable to find a global source for a D-type displayport passthrough. Because of this, I’ve included HDMI passthrough options in the BOM.

For safety, I won’t go through the process of how to wire up the AC inlet. I will say that the down angle C13 power cable is used for running internally from the PSU to the inlet. If you don’t immediately know exactly what to do with that info, stop and consult an electrician. I am not responsible if you disregard this warning and do this step wrong. Mains voltage can cause serious harm and it will not care one bit.

Panels

I have included DXF files for the 3mm thick side panels that you can have cut via any of the online or local CNC/laser cutting services. DXFs are included for the individual panels as well as one that has been panelized which can help lower the price depending on the vendor doing the cutting. The panelized version should snap apart and can be cleaned up with a sharp set of flush cutters or a hand saw.

The fan intake duct and grill sandwich the  right side panel and there is a groove on the duct that a piece of TPU filament can be glued into acting as a gasket against the fan. 

Print Recommendations

As with Voron projects, the recommended filament is ABS. Other materials may work but are untested and may cause issues with fitment and heat. All parts are exported in their correct print orientations.

Recommended Print Settings:

• 0.4mm nozzle

• 0.4mm forced line width

• 0.2mm layer height

• 4-5 walls

• 30-40% infill

There are a handful of parts that have multicolor alternatives which are included in the alternative parts section and are noted in the file names. The current multicolor parts are the panel clips, bottom component frame mounts, and the skirts. The clips and mounts will require a color changing setup. The skirts can be printed with just a simple filament change after the first 5 layers (1mm).

All parts are designed to print without supports except for the skirts and the fan duct, both of which have built in supports. 

All STLs are organized into their respective assemblies. Parts designed to be printed in your accent color labeled with an “(a)” at the beginning of their file name and parts designed to be printed in TPU filament are labeled with a "(tpu)" at the beginning of their file name. All other parts are meant to be your primary color but do what you want, I’m not your dad.

Assembly

Assembly of Muninn is fairly straightforward. There are essentially two main assemblies, the 2020 extrusion frame and the main component frame.  

My recommendation would be to assemble the frame as shown below then attach the skirts and deck panel. A tutorial for drilling, tapping, and using blind joints can be found HERE.

Then you can prepare the component frame and install your components.

After you have these two assemblies complete, you can simply drop the component frame down into the extrusion frame and secure everything as well as install the final two 100mm 2020 extrusions.

Once that is completed you can go ahead and wire up everything and do as much or as little cable management as you would like then install your panels and handle. 

Congrats, you’ve now assembled your Steam Machine mom said we had at home. Go ahead and play all of those games you always say you’re going to get around to.

Credits

• Voron Design Team for design language inspiration

• @dola.media for beta testing