1 Topic by w_smith

  • w_smith
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Topic: PID for bed heater?

I've just replaced the stock hot-end on my SD4 with an E3D head, and ran the autotune PID stuff as detailed at:

http://reprap.org/wiki/PID_Tuning

Which seems to have worked.

There's some stuff in the above link for tuning the PID constants for the bed, and I ran it and got some numbers, but they don't seem to be saved (M304 command returns OK without any numbers, and M503 shows some stuff but not the bed constants), and the bed isn't any more stable in temperature than before.

Does this board just not support bed PID?

Thanks!

2 Reply by wardjr

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Re: PID for bed heater?

Once you have the PID numbers you could always edit them in your configuration.h and re flash the board.  That's how I do mine.

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3 Reply by carl_m1968

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Re: PID for bed heater?

You would also need to look at the Configuration.H tab in your firmware to confirm if your Bed is set for PID or Bang Bang. Most of the time the bed is set for Bang Bang by default which just switches it off and on to control temp. If you get no PID numbers on a read back then my bet is your firmware has your bed configured for Bang Bang.

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4 Reply by jagowilson (edited by jagowilson 2015-05-01 17:43:35)

  • jagowilson
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Re: PID for bed heater?

The stock bed is fairly poorly insulated... I haven't insulated mine better just yet but I experience temperature deltas of +/-2.5C during prints even after several autotunes. It would help if the bed got to temperature before the PID autotune cutoff (which I think is adjustable), but I've done my autotunes with the bed already hot. Point being, maybe consider better insulation for the bottom of the bed in conjunction with auto tuning.