Building a Custom Rear Case for the Ender 3

Published 2021/01/03 by Jordan Hay

Recently I acquired a modded Ender 3 with the SKR 1.4 controller and automatic bed levelling. The custom case the previous owner printed I found to be insuffecient as when the heated bed reached its endstop it would stress the wires as they got near their maximum length. I knew I couldn't keep this design for long so I began designing my own rear mounted solution.

My criteria:

  • Rear mounted.
  • Room for SKR 1.4 + Raspberry Pi.
  • The USB cable going from the Pi to the SKR 1.4 should be contained within the case.
  • The Pi's Ethernet + Power + one of the USB ports should be accessible from the outside.
  • Ideally I should be able to pick up the entire printer without the case falling off.

I used Fusion 360 to develop the 3D model of the case. This was my first use of Fusion 360 to design something I intended to print.

After a first failed print I added an extension to the front which gave the cable between the Pi and SKR 1.4 more room in order for it to reach between the two.

I noticed some defficiences with the first design. The case did not account for the other ports on the Pi, as such it could not fit into the designated space and I had to cut some holes to make it work while I revised the design. The slots for the screws that will go into the metal extrusions also needed expanded by a few mm, and the space between mounts for the SKR 1.4 board were also too wide.

I also decided that once printed I would find a cover for the holes under each board. I presume I added them in to save filament but I'm not entirely sure. They wouldn't be the only exposed PCB on the Ender 3 but I think it is best to cover them if I can.

Second Iteration Installed (Without Lid)
The second print solved the warping issue and all of the other size issues. My Pi, SKR 1.4, and all the associated cables fit inside the base without issue.

Now with a working base design I had to develop a lid for the case. My original plan had been to have a two piece lid, although now with the extension for the communication cable I would need an extra piece.

The lid pieces printed successfully and friction fit in place, the half lid over the SKR 1.4 has a vent for the 40mm fan to keep the SKR 1.4 cool. 
Mark II in Fusion 360

For me it wasn't good enough.

I started again from scratch, dropping the requirement for the Pi-to-Mainboard cable being contained in the case (I thought this would result in a more regularly shaped case).

I avoided much of the issue I had with lining up ports correctly on Mark I by importing models of the SKR 1.4 and the Pi I found online.

My Mark II design adresses these few main issues I found with the Mark I:
  • Irregular shape to accomodate the Pi-to-Mainboard cable was weak not to mention unsightly.
  • Lid was in two pieces and the leftmost piece had a tendency to slide away, no actual screws were holding it down.
  • No vent for air to come out of.
  • Mark II installed.
    Bottom of Pi and mainboard are exposed which could potentially cause shorts.
  • Insufficent mounting points to the printer, resulting in drooping when printer is moved.
The Mark II is satisfactory for my needs, however I have some improvements to make:
  • Fan cover, current design has potential for small pieces of discarded filament or the like to fall in through the fan, potentially damaging the control board.
  • Exposed Pi-to-Mainboard cable, I know I had issues with covering this in Mark I but I do like the idea of it also being incorporated into the case somehow.
  • Pi relies on external power, it would be nice to have it all powered by the same system although the power supply for the printer could then never be turned off in that case.

Source code MIT License © 2021 Jordan Hay | Website Content © 2017-2022 Jordan Hay