My heated bed came packaged together with the RAMPS 1.4 board, the endstops and a whole bunch of wires. The board’s type is MK2b, and can be powered with both 24 and 12 volt. Since my power supply only provides 12V, I chose the latter.
Here a close-up of the empty contacts. P2 is for the NTC. Solder pad 1, 2 and 3 are for 12V, ground and ground respectively. If you are using 12V, you have to connect solder pad 2 and 3 together, otherwise you will only heat half the board.
Below the contacts for the NTC (thermistor)
Place the thermistor. Tape one of the thermistor legs to the board with Kapton tape. Make sure the legs do not connect with each other.
Solder the legs to the heated bed and isolate the other leg, and the thermistor with Kapton tape as well.
I chose to place the power indicator led on the plywood board instead of fiddling with a SMD led on the heated bed. A standard led won’t work with 12 V, you have to use a resistor to lower the voltage (see also chapter 1)
Mounting the Heated Bed on the plywood board
- 7x M4 Nut
- 4x M4 Threaded rod xx mm
- 13x M4 washer
- 3x Spring, length 20 mm, outside diameter: 10 mm, inside diameter: 8mm
- 3x M4 Wing bolt
Mount a threaded rod on one of the corners and tighten with nuts. This will be the fixed point of the board.
Place the threaded rods on the other three points, mount the springs and washers. Don’t install your wing screws like this; they can collide with your hot-end .
Now proceed to chapter 7: The RAMPS 1.4 board.