A printable expansion box for the rc2014

When the Front Panel Kit for the rc2014 was announced, I was facing a problem. When I had built my own rc2014, I decided to create an enclosure using Makerbeam XL and the skirts from the Voron 0.2. It seemed a sensible way to go about it at the time, since I already had most of the hardware and had printed the parts before. I had assumed that eventually, I'll get some plexiglass or make a nice little enclosure for it with a nice front panel and switches.

And then an official front panel with nice switches --and an LCD! --was announced. "Maybe I can adapt it for my existing case..." I told myself. Soon, though, it became obvious that wouldn't work and I'd have to cut quite a bit of material off to make it work. This was double-unfortunate, as I didn't want to damage that pretty front panel with rude power tools, nor did I want to loose the key reason I had built an enclosure in the first place.

See, I didn't just want my rc2014 to be a stock system. I wanted it to have it's own internal power supply and a place for a VGA to HDMI converter for easy display. The idea was to make it simple to transport the machine to another part of the house, or to elsewhere for a showing without needing to carry an additional bag of adapters. 

In this way, the original case I had made worked really well. Once set up, it was a simple matter of plugging in an IEC mains line and connecting to any HDMI display. 

The problem was, I really wanted that fancy front panel...

Not wanting to modify the front panel kit, nor make my own front panel, I decided to go ahead and get the Blue Box enclosure for the system. Originally, I was thinking there might be room inside the box for me to mount both the VGA to HDMI adapter and the power supply unit inside. "At worse, I'll mount it on the back," was a plan that would have also worked, if there wasn't also a rear panel kit in the rc2014 future as well...

Not having either option, I started to wonder if I could 3D print an expansion box to house my accessories. At first, I thought about modifying the skirt prints from the Voron 0.2, but I quickly found that untenable. I didn't have the traditional CAD skills necessary to do that modification on my own. What I did have, however, was growing knowledge of OpenSCAD, a rather non-traditional modeling program which used software code for modeling rather than graphical operations and configuration. The fact that my brain already things in code made it much easier for me to pick up. 

For inspiration, I turned again to the Voron 0.2 design. There, the bottom electronics box is made of four printed feet, with one foot also the housing for an IEC power inlet. Lighter "panel skirts" are mounted between the feet, which allow for airflow over the electronics. I decided to use the same approach for what was quickly being called The Power Base. 

One problem, however, was how to mount the electronics. Originally, I was going to just use VHB tape and call it a day. When I went looking for the tape, however, I couldn't find it! Instead, I decided to use this as an opportunity to try something new. The Voron 0.2r1 and the 2.4 make use of DIN rails to mount electronics. DIN rails aren't as common in the US, but appear to be more common Europe where they're used for electrical boxes. Thankfully, you can still order them here.

The DIN rails also provide some additional reenforcement for the foot posts. Each foot post only mounts to the Blue Box using one screw and a threaded insert. This takes advantage of the holes left by the box's original plastic feet, which I removed. This, however, makes each foot post unstable as it can swing around on that one mounting hole. The DIN rails help constrain it by linking two foot posts together. Neat!

Since I was designing the entire thing from scratch anyways, I wanted to spend some time to include something which "evokes" the rc2014. The thing is, other than the color blue, the only other design element I could find was the logo. The rc2014 logo is just "RC2014", but done in a style of many little parallelogram boxes with a drop shadow under each one. It has a great, retro terminal feel. I wanted to incorporate that.

So, I made parallelograms the basis of the entire design for the Power Base. Each foot post was a parallelogram wrapped around each corner. Each panel was a parallelogram. The grid of each panel was made of parallelograms. The foot posts were later "embossed" with a parallelogram pattern to match the size of the grids on the panels to give the sense of continuity. 

This resulted in some interesting problems which had to be solved in the CAD. The Voron 0.2 skirts had threaded inserts in the foot posts which the panels secured to. In the Power Base, the reverse is true; there are a pair of holes on each side of each corner through which two screws pass through. The panels have threaded inserts. To make the inserts easier to install in to the angled sides of the panel, a 90-degree flat was made to register the inserts against. Bolting the panels from the outside also had the side effect of making panels easier to remove and reinstall, as the screw heads weren't in an awkward position. 

While I originally wanted each panel to be "scooped out" using a curved, organic shape, I found that unworkable. First, I couldn't get the positioning right for the curves. Secondly, it just didn't look right. After a re-think, I wrote a method to make a parallelogram frustum, and used that to scoop out the majority of the panel interior. This gave each panel a sharp, angled look while reducing print time and material.

Another goal was connectivity. I wanted to use keystone ports to provide customizable connectivity for the Power Base. I also had a bunch of HDMI, and USB keystones on hand. Ethernet is the most common keystone by far, but there's no need for it with the rc2014. 

Except when comes to VGA. My original design used four keystone slots, but I found this was a problem for getting VGA into the Base. Ideally, you would be able to connect and disconnect everything between the Base and th3e rc2014 without having to open either enclosure. While there are some "VGA Extenders" which use the same connectors as Ethernet, I didn't want to risk making one of those cables myself.

Instead, I opted to get a "VGA Mini Gender Changer" -- a name which makes me giggle each time. These are little more than electrical passthroughs for the VGA cable, allowing you to connect one VGA cable to another. I got the idea by looking at panel mount VGA ports, most of which are plastic wrappers for the gender changer. So, I got the adapter itself and designed in a spot in the rear panel to drop it in. The result is not only clean, but provides enough structural connection to the rest of the panel to take some abuse.

I've designed several things in OpenSCAD before, but this was by far the most complicated project I've yet attempted. The details and variety of parts required me to push my own limits and learn some new techniques with the application and programming language. My poor 2017 laptop often had trouble keeping up rendering the full model at once. Still, the design was successful, looks great, and meets all my requirements.

I have the source files available on Github. At the time of this writing, they're a huge mess and difficult to sort out what needs to be printed. I hope to clean the files up, make them neater, more readable and modular. Once that's done, I'll post them to popular 3D printing sites like Thingiverse and Printables.