AutoTune Hotend and Bed Question. Ramps 1.4

Re: AutoTune Hotend and Bed Question. Ramps 1.4

dave3d — Sun, 02 Mar 2014 15:00:49 -0500

I tuned mine for 230 deg C ( I mostly print ABS). This was with a resistor heater. I haven't used a cartridge type yet.

Send: M303 S230

I got
Kp 15.59
Ki 0.65
Kd 94.00

Looks like your proportional band Kp is too wide causing overshoot.
Suggest you try my settings to get you started then do another tune.

Also I am using a bog standard Jhead from hotends.com. 1.75mm filament, no insulation and a 40mm cooling fan continuously on the peek bit. The thermal characteristics of my system may be different than yours.

Re: AutoTune Hotend and Bed Question. Ramps 1.4

Janski — Sun, 02 Mar 2014 11:04:27 -0500

Hey Dave3d,

I just bought a 12 v 40w Professional Strain Reflief Heater for 3d Printers (5mm OD). Software is still running on the old Kp Ki Kd setting from the old RD59 resistor.

When i try to auto tune this heater here is what I get:

echo:PID settings:
echo:   M301 P100.84 I18.27 D139.12
>>>M303 E0
SENDING:M303 E0
echo:SD init fail
PID Autotune start
PID Autotune failed! Temperature too high

It is no longer showing me the temp breakdown as it heats up. instead it just LAGs and then it output the message.

The Heater works well, actually to well. Hangs about 10 degrees higher than it should. I assume its due to the Kp Ki Kd setting.

Can anyone or you advise or has ran into this with Cartridge heaters?

Sincerely,

Janski

Re: AutoTune Hotend and Bed Question. Ramps 1.4

DaveX — Wed, 26 Feb 2014 01:22:34 -0500

Just use the last set of autotune values. They have excessive precision compared to the process--you probably couldn't notice a difference if you varied them from the autotune values by 10%.

'M303 E-1' would autotune the bed, if your Marlin is configured with #define PIDTEMPBED.

See [reprap.org] for some details.

Re: AutoTune Hotend and Bed Question. Ramps 1.4

dave3d — Tue, 25 Feb 2014 16:34:14 -0500

My Ord Bot bed is set up in Marlin with just on/off control or so called bang-bang. It is full on if the temp is under the set point.
I did about 3 PID tunes on the extruder and took an average of the values.

Re: AutoTune Hotend and Bed Question. Ramps 1.4

jbernardis — Tue, 25 Feb 2014 15:43:38 -0500

You should enter the last values reported into your firmware. As far as the bed is concerned, most people just leave it a bang-bang control for which tuning is not really necessary. If you have PID enabled for the bed, I guess it could benefit from a tuning, although I wouldn't know how you'd do it.

AutoTune Hotend and Bed Question. Ramps 1.4

Janski — Tue, 25 Feb 2014 14:02:12 -0500

Hey Guys,

I just recently learned about autotuning. Newbie here.

From Pronterface. M303 E0 S230 C5 to get the Kp Ki Kd Values.

Question 1: I assume it is the last one or do I average out the values that Pronterface spits out?

Question 2: Do i have to autotune the heated bed as well? the bed has a hard time reaching 110C and I assume this has to do with the autotune function. What is the code I would have to run if the bed is attached to D10 on Ramps 1.4 board?

Please advise:)

Sincerely,

Janski