From the day I built my Mk3S, it bothered me how much the heatbed wire connector protruded from the back. Between the long connector itself and the fact that the wires are sticking directly out the back, you can't place the printer near a wall on that side, and any enclosure needs to be much larger than it otherwise would have to be.
So I finally made a low-profile design. With this design, the wire loom comes out the back corner pointing to the left side of the machine, with plenty of slack to make sure it isn't a problem when the bed moves all the way forward. It means that you can place the machine 9cm (3.5 inches) from a wall in the back (measured to the back of the frame). If you also mount your screen to the side using one of the many brackets available here, you can fit the entire printer on a 43cm shelf (17 inches) or inside an enclosure about 46.5cm (18.25 inches) deep.
Print both parts with the flat faces down. I used Prusament PETG Galaxy Black to match my printer.
This requires three M3x16 cap screws and 3 M3 nuts.
Installation:
Turn off and unplug the printer, just to be sure.
Move the heatbed forward, and make sure the zip-tie holding down the back end of the left Y-axis rod is well trimmed and the head is as low as possible. Then move the heatbed all the way back for good access.
Unscrew the three screws on the cover and remove it.
Loosen the right (positive/VCC) connector, and turn the clip so it points straight toward the right side of the machine. I would recommend partially tightening the screw at this point, and only tightening it after a test-fit of the cover. But don't forget to tighten it before closing the cover.
Unscrew the left (ground/GND) connector, and move the ground clip to the bottom of the heatbed, with the wire pointing diagonally toward the right side of the machine, angled just in front of the hole between the two connectors. The small black two-wire thermistor cable should go beside it, clear of the central hole, which will have a screw coming through it.
top view
bottom view
(you can also route the thermistor wire between the ground wire and the heatbed just behind the crimp connector)
See the photos above for the way the wires need to be routed. You need to make the positive (VCC) wire curve fairly tightly, but be sure not to kink it. The wrapped wire loom needs to be routed straight to the right side of the tab, halfway under the bed.
Test fit the cover, to make sure that it can close with the central screw running through the central hole and the hole in the heatbed between the two connectors. Make sure none of the wires is crimped or squashed by the cover. If you don't want to tilt the machine, you can inspect the bottom with your phone on selfie mode.
bottom view closed - note routing of thermistor wire
When the placement is right, make sure to tighten the screws on the VCC and ground connectors.
Insert the nuts into the bottom cover, and carefully screw down the cover with all three screws. Make certain the wires are still well routed, and that the assembly clears the frame and the zip-tie when you move the heatbed forward.
Plug in, switch on, and print!
[Note: The Mk4 appears to have a different design in this location, so this model presumably won't work on the Mk4.]
Reed Bowman
