Heated Bed Too Hot
So I've finally got my home built printer up and running. But I've run into an issue with the heated bed. I have it set to pre-heat to 60° C, but it overshoots and levels at 120° C. Here is my current setup:
Firmware - 1.0.3 Dev
Controller - RADDS 1.5
Bed Heater - 750w@110v controlled via SSR
Bed Thermister - NTC 100K 3950
Initial Firmware Settings:
// ############# Heated bed configuration ########################
#define HAVE_HEATED_BED 1
#define HEATED_BED_PREHEAT_TEMP 60
#define HEATED_BED_MAX_TEMP 120
#define SKIP_M190_IF_WITHIN 3
#define HEATED_BED_SENSOR_TYPE 14
#define HEATED_BED_SENSOR_PIN TEMP_1_PIN
#define HEATED_BED_HEATER_PIN HEATER_1_PIN
#define HEATED_BED_SET_INTERVAL 5000
#define HEATED_BED_HEAT_MANAGER 0
#define HEATED_BED_PID_INTEGRAL_DRIVE_MAX 255
#define HEATED_BED_PID_INTEGRAL_DRIVE_MIN 80
#define HEATED_BED_PID_PGAIN_OR_DEAD_TIME 196
#define HEATED_BED_PID_IGAIN 33
#define HEATED_BED_PID_DGAIN 290
#define HEATED_BED_PID_MAX 255
#define HEATED_BED_DECOUPLE_TEST_PERIOD 300000
#define MIN_EXTRUDER_TEMP 150
#define MAXTEMP 275
#define MIN_DEFECT_TEMPERATURE -10
#define MAX_DEFECT_TEMPERATURE 290
#define MILLISECONDS_PREHEAT_TIME 30000
#define HAVE_HEATED_BED 1
#define HEATED_BED_PREHEAT_TEMP 60
#define HEATED_BED_MAX_TEMP 120
#define SKIP_M190_IF_WITHIN 3
#define HEATED_BED_SENSOR_TYPE 14
#define HEATED_BED_SENSOR_PIN TEMP_1_PIN
#define HEATED_BED_HEATER_PIN HEATER_1_PIN
#define HEATED_BED_SET_INTERVAL 5000
#define HEATED_BED_HEAT_MANAGER 0
#define HEATED_BED_PID_INTEGRAL_DRIVE_MAX 255
#define HEATED_BED_PID_INTEGRAL_DRIVE_MIN 80
#define HEATED_BED_PID_PGAIN_OR_DEAD_TIME 196
#define HEATED_BED_PID_IGAIN 33
#define HEATED_BED_PID_DGAIN 290
#define HEATED_BED_PID_MAX 255
#define HEATED_BED_DECOUPLE_TEST_PERIOD 300000
#define MIN_EXTRUDER_TEMP 150
#define MAXTEMP 275
#define MIN_DEFECT_TEMPERATURE -10
#define MAX_DEFECT_TEMPERATURE 290
#define MILLISECONDS_PREHEAT_TIME 30000
It doesn't matter if I pre-heat from the RADDS display or Octoprint. Either way it heats to, and stays around max temp.
I tried lowering the max temp to 60° C using the following settings:
// ############# Heated bed configuration ########################
#define HAVE_HEATED_BED 1
#define HEATED_BED_PREHEAT_TEMP 60
#define HEATED_BED_MAX_TEMP 60
#define SKIP_M190_IF_WITHIN 3
#define HEATED_BED_SENSOR_TYPE 14
#define HEATED_BED_SENSOR_PIN TEMP_1_PIN
#define HEATED_BED_HEATER_PIN HEATER_1_PIN
#define HEATED_BED_SET_INTERVAL 5000
#define HEATED_BED_HEAT_MANAGER 0
#define HEATED_BED_PID_INTEGRAL_DRIVE_MAX 255
#define HEATED_BED_PID_INTEGRAL_DRIVE_MIN 80
#define HEATED_BED_PID_PGAIN_OR_DEAD_TIME 196
#define HEATED_BED_PID_IGAIN 33
#define HEATED_BED_PID_DGAIN 290
#define HEATED_BED_PID_MAX 255
#define HEATED_BED_DECOUPLE_TEST_PERIOD 300000
#define MIN_EXTRUDER_TEMP 150
#define MAXTEMP 275
#define MIN_DEFECT_TEMPERATURE -10
#define MAX_DEFECT_TEMPERATURE 290
#define MILLISECONDS_PREHEAT_TIME 30000
#define HAVE_HEATED_BED 1
#define HEATED_BED_PREHEAT_TEMP 60
#define HEATED_BED_MAX_TEMP 60
#define SKIP_M190_IF_WITHIN 3
#define HEATED_BED_SENSOR_TYPE 14
#define HEATED_BED_SENSOR_PIN TEMP_1_PIN
#define HEATED_BED_HEATER_PIN HEATER_1_PIN
#define HEATED_BED_SET_INTERVAL 5000
#define HEATED_BED_HEAT_MANAGER 0
#define HEATED_BED_PID_INTEGRAL_DRIVE_MAX 255
#define HEATED_BED_PID_INTEGRAL_DRIVE_MIN 80
#define HEATED_BED_PID_PGAIN_OR_DEAD_TIME 196
#define HEATED_BED_PID_IGAIN 33
#define HEATED_BED_PID_DGAIN 290
#define HEATED_BED_PID_MAX 255
#define HEATED_BED_DECOUPLE_TEST_PERIOD 300000
#define MIN_EXTRUDER_TEMP 150
#define MAXTEMP 275
#define MIN_DEFECT_TEMPERATURE -10
#define MAX_DEFECT_TEMPERATURE 290
#define MILLISECONDS_PREHEAT_TIME 30000
With these settings, the bed hits around 70° C and then generates a sensor error.
At room temperature, I'm seeing the following temps:
Room: 26.5° C
Enclosure: 27.6° C
HotEnd: 28.1° C
Bed: 28.4° C
Comments
Does the firmware report the high temperatures? Check the temperature curve in Repetier-Host along with bed output. That normally gives you an idea what firmware does. I guess your bed is somehow overpowered so it is easy to reach 120 with bed PID values. Maybe first just test bang-bang as method and see how it behaves. There it gets disabled > 60°C and enabled below so it will swing a bit around the target temperature, which is no problem for a bed.
Your PID values look quite extreme so these will be the main problem I think.
So what happens if you only turn on the extruder does bed also heat up and does extruder heat up as well? In that case I would check the hardware. There might be a bridge on the board between extruder and bed pin so extruder pin also enables bed mosfet. I would suspect the same then if you heat the bed, meaning heating up extruder also.
Or you have set same pin for both outputs in configuration.