The Heated bed

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.

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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.

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Below the contacts for the NTC (thermistor)

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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.

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Solder the legs to the heated bed and isolate the other leg, and the thermistor with Kapton tape as well.

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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)

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Mounting the Heated Bed on the plywood board

Needed parts

  • 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

 

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Mount a threaded rod on one of the corners and tighten with nuts. This will be the fixed point of the board.

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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 .

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Now proceed to chapter 7: The RAMPS 1.4 board.