How to Fit the Heated Bed to the Y Carriage of Your RepRap 3D Printer

By Kalani Kirk Hausman, Richard Horne

You will eventually need to prepare to fit the heated-bed to the laser-cut Y axis on your 3D printer. Make sure you have all the parts required for this procedure before you get started.

Part Details Quantity
Heated-bed printed circuit board Model MK2a is most common, ready-wired and fitted with an LED
indicator.
1
Wired thermistor 100k thermistor, ready-wired. 1
Kapton tape High-temperature Kapton or PET tape for fixing thermistor to
heated-bed printed circuit board.
100mm x 20mm tape
M3 nuts These M3 nuts should be stainless steel if possible. 4
Insulation material Various options are available. 1
Glass print surface A standard 200mm x 200mm glass mirror tile, 4mm thick. 1

When you’ve gathered and laid out the required parts for assembly, follow these steps:

  1. Orient your heated-bed printed circuit board (PCB) so the electrical connections are at the front of the machine and the wires run under the PCB.

  2. Turn the bed over so the wires are in front of you and are vertical relative to the printed circuit board.

  3. Place the thermistor bead into the center of the MK2 heated-bed. You will see a small hole to insert it into.

  4. Fit the thermistor bead level with the top surface of the heated-bed.

  5. Fold the wires on the underside of the printed X carriage onto the three linear bearings that are fitted to the smooth rods of the horizontal X.

  6. Tape down the wires of the thermistor with the high-temperature Kapton tape; also tape over the hole that the thermistor bead is sitting in.

  7. Fold down the main power wires onto the bed facing away from you.

  8. Tape both the heating wires and thermistor wires together to form a curved single set of cables facing back to the machine.

    You can now optionally fit some insulation material to the underside of the heating printed circuit board. This is a very good idea as it helps the bed heat up quicker and also minimizes heat loss and wasted power.

    Materials should have been provided in your kit, and can range from cork, metalized cardboard, fiberglass insulation, or a custom sheet of high temperature insulation. This is usually fitted with Kapton tape and also helps hold the cables away from the printed circuit board.

  9. Turn over the heated-bed printed circuit board so the LED is at the front and wires face backward on the underside.

  10. Place the heated-bed onto the Y axis 20mm M3 posts fitted earlier.

    The M3 nuts already fitted onto the posts now suspend the heated-bed at a set distance from the Y axis. You can fit four more M3 nuts to tighten down the heated-bed. By moving these nuts, you can alter the position of the heated-bed with respect to the Y axis so that it’s flat at all corners, suspended at a set distance, and level.

    No need to level the bed just yet; doing so will be a required part of calibration later on, before the machine is ready to print.