Sci-Pi Crate

Introduction: Sci-Pi Crate

About: Interested in creating and sharing.

The "Sci-Pi Crate" is a case for Raspberry Pi 4's that also has mounting options for 3.5 inch hard drives and a 120mm fan.

There are two configurations for the Sci-Pi Crate:

  • Configuration "A" supports one Raspberry Pi and two 3.5 in hard drives.
  • Configuration "B" supports three Pi's and three 3.5 in hard drives.

My goals with this design were to create a case I could use for a Raspberry Pi based NAS (network-attached storage) that looked interesting. It evolved from that into also supporting multiple Pi's for use as a cluster.

What you do with the Pi's is up to you, but I think the natural usage of this case is for either a NAS or docker/k8s cluster.

Step 1: Tools and Materials

Tools:

  • 3D printer
  • soldering iron
  • hex keys
  • wire cutters

Optional Tools:

  • Dupont Crimps
  • keystone punch-down

Materials:

  • 3D printed parts
  • raspberry Pi 4 (1-3)
  • 3.5 inch hard drive (1-3)
  • M4 screw (8) [40-45mm]
  • M4 nut (8)
  • #6-32 UNC crew (4-12) [4-6mm]
  • M3 screw (4-12) [4-7mm]
  • 5V/3A dc/dc converter
  • Sata to USB3 w/ 12V power
  • 120mm fan
  • DC Power Connector FC681493
  • M2 screw (2) [4-7mm]
  • Cat-6 Keystone jack
  • Cat 5e/6 cable

Optional Materials:

  • Dupont connectors
  • M3 screw optional (4-12) [10-15]
  • M3 nut optional (8)
  • resistors for fan

Step 2: Design Process

I used Fusion 360 for this design. I'm not a pro but I have been getting better and I'm happy with how this design turned out.

My method for this project was to download models of as many of the components as I could from grabcad. I like to do this so I can see how things will look and fit together. I find grabcad.com to be a great resource and I can often find models that I can use to speed up my designs and let me focus on the part I'm creating and not worry about taking 100 detailed measurements or reading technical docs to ensure the parts will fit once printed.

Once I had all the standard components I could get started with my design. I imported all the items I would need in the case and moved them around trying different layouts. Each time I got a stack of components that I liked I would draw a box around them and consider that my internal volume and shape. Then I would think about how I could manage the wires and what exterior designs could fit that internal shape and look interesting. After going through a few of these cycles I concluded that I was going to end up with a rectangle. So now I started to think about and look-up art from movies, games, anything I could think of that could be an inspiration.

Eventually, I found LoneWolf3D's work on artstation.com. I thought that their design would be perfect for my project. It was an interesting design that had features I felt confident I could emulate. I also thought the circular details on the ends would work well for me to use as inlet and exhaust for my fan.

Any time I do a design for 3D printing I think about the part orientation and how I can split objects to improve print performance. Print performance for me is things like layer orientation for strength or details, reducing overhangs and bridges, and avoiding monolithic prints that could cause major setbacks if the print fails. In addition to these goals, I also wanted to try and reduce overall plastic usage. This has two main benefits, reduced cost, and reduced print time.

Step 3: Printing

Printing was straight forward. Since I took the extra time in CAD to plan for printing I did not have to worry about things like support for most of the prints. There is one part (B-bottom) where I decided using support was a better choice than trying to split or change the design of the part to avoid support.

I used Cura for slicing but you should be able to use whatever slicer you prefer since we shouldn't need any advanced features, like manual support.

You can view and download the STL's from my Thingiverse page

Step 4: Assembly

I think pictures are easyer to understand than descriptions, so you can view the models at these links Full Config A Assembly, Config B Assembly. The models can be rotated, exploded, and viewed to allow you to see how the pieces are intended to go together.

The hardest part of the assembly for me was building the power distribution board. This step could be skipped by buying a pico-PSU, but I had some buck converters and connectors already so I decided to build my own board. I am not including my schematic because I didn't make one 😜 but I will describe the design goal so you can understand what is needed.

We need 5v and 12v. the power comes into the case as 12v so that is easy but then we need to convert some of it to 5v for the RPi. I used some MP1584EN DC-DC buck converters because that's what I had. I also decided I didn't want the fan to run at 100% so I wired in some resistors. If you choose to add resistors to your fan circuit make sure to keep track of how many watts they will need to dissipate and the rating of your resistors. To calculate the watts needed for the resistors you use Ohm’s law ( V = I × R ) and the power rule ( P = I × V ).

Step 5: Conclusion

This case is just the start of a Raspberry Pi project. It offers containment for 1-3 Pi's and 1-3 full-size hard drives. I enjoyed designing this case and if you use it in a project I would love to hear about what you made.

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