DyzEnd + DyzExtruder Pro TPU and Temperature Issues

[Justin Funderburk]

All,

Been in contact with support for several weeks now trying to come up with some ideas. First this started out with TPU issues where I got continuous clogs at the beginning of the heatbreak. Decided to reduce the motor current, and ensure it was not heat creep. I still got he issue, no matter what changes I made it still happened. I got lucky once and finished a print, otherwise it would also fail at some random interval. Eventually I gave up until I can upgrade the cooling on this system (maybe water cooling, etc) and see if that will fix the issue.

Fast-forward to now, I am trying to print some exotic PA6-CF nylon with CF threads, and I am having insane amount of issues with PID tuning and heater issues. The heat will not calibrate well enough to print. I had to dumb my "smart safety" features in Klipper to even get it to print, but with a set-point of 280 the temp ranges from 270 up to 290 and obviously the print quality is garbage like this. Has anyone else running klipper manager to print at temps over 230? I can do fine up til about 230 degrees, and then the PID tuning does nothing to help. I have limited max-power to 0.7, and tried several other tricks. I could not even get this thing to print with default PID tuning.

[extruder]
step_pin: PB3
dir_pin: !PB4
enable_pin: !PD2
microsteps: 16
rotation_distance: 26.20
gear_ratio: 5.65:1
#control: pid
#pid_Kp: 19.3
#pid_Ki: 2.1
#pid_Kd: 44.6
nozzle_diameter: 0.400
filament_diameter: 1.750
heater_pin: PC8
sensor_type: Dyze500
sensor_pin: PA0
min_temp: 0
max_temp: 480
pressure_advance: 0.06
max_power: 0.7

[verify_heater extruder]  
heating_gain: 2
check_gain_time:35  
hysteresis: 10  
max_error: 130

[tmc2209 extruder]
uart_pin: PC11
tx_pin: PC10
uart_address: 3
run_current: 0.65
driver_PWM_GRAD: 10
stealthchop_threshold: 99999

*# [extruder]
#*# control = pid
#*# pid_kp = 15.875
#*# pid_ki = 0.460
#*# pid_kd = 136.920

[Technical Support]

Hi Justin!

Good reflex on the motor current. Usually, TPU aren't so sensitive to temperature. What's the shore hardness of the TPU you are using? Also, what's the brand? We've seen some drastic flow impact on the brand. For example, the 85A Ninjaflex are much harder to extrude than most others. TPE are in general much easier to extrude.

Regarding the PID, I strongly suggest running a PID tuning for each setpoint you want to use. Depending on the firmware, a PID set of values is good for a small range of setpoints. The further away you are from the tuning setpoint, the less stable you are. As a general rule of thumb, I would consider a PID valid within +- 25°C of the tuning setpoint.

Finally, are you using a PT100 or a thermistor? The high temperature thermistor is known to have a higher time constant (time for the sensor to output a given temperature), which can make it harder to get the right tuning. Our PT100 and the low temperature (300°C) thermistor have faster time constant, thus are more reactive.

I hope it helps!

Phil Support Team
	100-1505 Saint-Thomas Lemoyne, Quebec, Canada, J4P 3S2
	dyzedesign.com

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[KJ Pecho]

I have the exact same issues with TPU. I've posted another thread about it previously. 98A Shore hardness. I have a hell of a time preventing what Phil has referred to as back pressure. The filament expands and get jammed in my extruder just before what I refer to as the extruder exit throat. (I don't see this part for sale in the spare parts page so not sure what the official name is) It appears that as TPU is flexible it can stretch or compress and as pressure builds in the hot end it creates a back pressure force while at the same time the extruder is continuously pushing forward, which compresses the filament, expanding it, and it gets jammed.